Showing papers by "Seoul National University published in 1980"

Feedback stabilization of linear systems with delayed control

Abstract: Feedback controls based on the receding horizon method have proven to be a useful and easy tool in stabilizing linear ordinary differential systems. In this paper the receding horizon method is applied to linear systems with delay in the control. An open-loop optimal control which minimizes control energy subject to certain side constraints is first derived and then transformed to a closed-loop control via the receding horizon concept. The resulting feedback system is shown to be asymptotically stable under a complete controllability condition. It is also shown how the receding horizon control suggests a more general class of stabilizing feedback control laws. The control laws of this paper are perhaps the easiest way to stabilize a linear system with delay in the control.

Histopathologic study on human sparganosis.

Abstract: Based on 16 cases of human sparganosis, a histopathological study was made. There was a striking similarity among histological features of sparganosis involving different tissues. The histological change of the affected tissues was characterized by a necrotizing and granulomatous inflammation with or without worm parasite in the lesions. There was also a remarkable polymorphonuclear leukocytic mobilization, predominantly of eosinophils, plasma cells and lymphocytes in and near the lesions. Tunnel formation lined by palisading histiocytes was another charateristic feature of the host tissue reaction. These findings were quite distinguishable from those of cysticercosis which were more localized and self-limited. Several features that were prominent in section slides of sparganum worm parasite were also noted. Laminated calcospherules found in the cytoplasm of the proliferating macrophages and giant cells were of diagnostic value of sparganosis in the absence of the worm, particularly when these were accompanied with tunnel-like lesion in the host tissue.

The free surface on a liquid between cylinders rotating at different speeds. Part III

Abstract: This paper is a further contribution to our work on the Weissenberg effect. One goal of our work is to show how the free-surface deformations on a viscoelastic fluid which is sheared between two concentric rotating cylinders can be used to determine rheological data about the fluid. In this paper we report the results of an experimental program in which free surface shapes have been measured on three viscoelastic fluids undergoing shearing in an apparatus consisting of a stationary outer cylinder and four interchangeable rotating inner cylinders. Experimentally-measured profiles are compared with profiles predicted from second-order theory, and found to be in excellent agreement for STP and TLA-227 in the range of applicability of the second-order theory, but there is some disagreement in the results for a 2% solution of polyacrylamide in 49% water −49% glycerin.

Comparative Efficacy of various Interval Mass Treatment on Ascaris lumbricoides Infection in Korea

Abstract: To observe the effect of various interval mass treatment on Ascaris ova and worm positive rates and worm burden per population, 2-month, 4-month, 6-month and 12-month interval schemes were designed and applied. All of inhabitants in nine villages of Hwasung Gun, Kyunggi Do, Korea were treated from April 1977 to May 1980. Each village consisted of 100~140 people, however, there had been 20~40 drop-outs in every treatment. Pyrantel pamoate was used in dose of 10 mg/kg. Evaluation of schemes was made by examinations both for eggs and for expelled worms. The drop-outs in former treatment was included because they were few in munber. The reults obtained were summerized as follows: 1. The pre-treatment infection status of A. lumbricoides was not significantly different between Groups; 32.5-42.2% and 33.8-46.2% in egg and worm positive rates respectively. The mean worm burdens were in range, 1.6~4.2 per infected and 0.61~1.42 per population. 2. Twelve-month interval treatment was by no means meaningful to be adopted as a strategy of Ascaris control because egg and worm positive rates and worm burden were returned to pretreatment level. 3. The shorter the treatment interval was, the lower the egg/worm positive rates and worm burden were. By repeating biannual, triannual and six-times-in-a-year treatments, the indices of prevalence showed the tendency of further lowering during later 2 years of follow-up. If the mass chemotherapy is adopted as a method of controlling ascariasis in a community, it should be repeated more than two times in a year to expect the gradual lowering of reinfection.

The Role of Bureaucracy and Regime Types A Comparative Study of Turkish and South Korean Higher Civil Servants

Abstract: The objective is to assess the validity of one general proposition that has been central to much of the thinking and theorizing among students of comparative public administration. It is that the political roles ofpublic bureaucracies vary systematically with the regime types. This proposition is examined in the context of two disparate political systems; Korea and Turkey. The data are derived from personal interviews conducted with 232 Turkish and 225 Korean civil servants of the highest ranks. The analysis focuses on three aspects of the bureaucracy: its policy-making role, its accountability to the public, and the character of its professional norms. The evidence lends no support for the proposition and thereby raises some questions about its validity.

Microscopic theory of condensed phase chemical reactions. I. Pair phase space kinetic equation

Abstract: A repeated ring kinetic theory describing the reversible chemical reaction A+B?C+D is obtained. We derive a kinetic equation for the equilibrium time correlation function of the solute pair phase space density. The solute–solvent and solvent–solvent interactions are described by a hard sphere potential. The solute–solute interactions consists of both hard and soft potential terms. This choice permits the use of a pseudo‐Liouville operator formalism to obtain the kinetic theory. This greatly simplifies the derivation by comparison with a Liouville operator formalism for continuous potentials. The solute is dilute such that the kinetic theory describes isolated solute pairs interacting with the solvent. The static memory function of the kinetic equation is treated exactly. It describes solute propagation induced by direct interaction, Enskog collisions with the solvent and by the potential of mean force operating between the solute pair. The dynamic memory function is obtained at the repeated ring level of ...

Effect Of Two-Month Interval Mass Chemotherapy On The Reinfection Of Ascaris Lumbricoides In Korea.

Abstract: Atrial to control reinfection cycle of Ascaris lumbricoides was made in a rural village in Korea by blocking the process of new egg production. Chemotherapy with pyrantel pamoate was repeated bimonthly in three hamlet groups, each consisted of 105~149 inhabitants of whole age group. In one hamlet (2.5 mg/kg dose) blanket mass treatment was repeated for 18 times from June 1977 to May 1980. In other two, 5.0 mg and 10.0 mg/kg dose groups, treatment was undertaken for 10 times from June 1977 until December 1987 and later reinfection patten was observed. Follow-up examination was made by whole-day stool collection for 2 days from each case after every treatment. The samples were examined both for eggs and worms, adult and immature young, of A. lumbricoides. The results obtained are summarized as follows: 1. The pre-treatment egg positive rate in Group A, B and C was 48.1, 45.3 an 37.8% respectively. 2. The lowest dose of pyrantel pamoate, 2.5 mg/kg was equally effective as higher doses in case of repeated use for reinfection control. 3. Among 4,311 pyrantel treatments, only 8 cases complained of side effects such as abdominal pain and diarrhea. 4. When the blanket mass chemotherapy was continued 18 times in Group A, all of the examined inhabitants were free from reinfection and egg production from 28th month (the 15th treatment) until the end of study period, for 8 months. 5. When the mass chemotherapy was stopped after 10 times, the egg positive rate returned gradually up to half of pre-treatment level within one year. 6. From the analysis of total 124 positive cases during the course of follow-up, it was revealed that the mass chemotherapy with 2-month interval was successful for the suppression of fertilized egg production. However, social factors such as infected immigrants or absentees were inevitably encountered and involved in the fertilized egg production. Summarizing the results, at least 28-30 months were needed to eradicate A. lumbricoides in the subjected area of Korea, by repeated blanket mass treatment bimonthly with a quarter dose of pyrantel pamoate. Furthermore, to lessen the social factors as a source of later reinfetion, the project area of control programme should be extended as wide as possible.

Metabolism in vitro of capsaicin, a pungent principle of red pepper, with rat liver homogenates

Abstract: Publisher Summary This chapter discusses the metabolism of capsaicin—a pungent principle of red pepper—with rat liver homogenates in vitro . Capsaicin is the main pungent principle of red pepper. Capsaicin and its homologs, that is, capsaicinoids, have been used in medicine internally and externally. In large doses, capsaicin can cause damage to gastric mucosa and may induce hepatitis. The chapter presents the evidence that capsaicin is metabolized in liver by a mixed function oxidase system. Several other synthetic capsaicinoids and zingerone were also studied with the liver enzyme to find out the structure-activity relationship. The chapter describes a study in which an attempt was made to determine whether the rat liver enzyme system could metabolize capsaicinoids. It was proved by detecting a metabolite that a microsomal enzyme preparation from locally available adult rats—mixed strain—could oxidize capsaicin. This function of oxidation was much enhanced by administration of sodium phenobarbital.

Chronologic growth pattern of Ascaris lumbricoides.

Abstract: The chronologic growth patten of Ascaris lumbricoides was made by the maximum length of worms collected from inhabitants after mass chemotherapy with pyrantel pamoate by various interval; 2-month, 4-month, 6-month an 12-month. The results obtained were summarized as follows: 1. When the collected 497 worms were plotted on weight/length chart by treatment interval, there was always size limitation in each group, permitting the idea of maximal growth in a given period of infection. 2. The maximum lengths in each interval treatment, 2, 4, 6 and 12-month were; 12.5, 16.4, 19.2 and 22.8 cm in male and 14.2, 22.0, 26.2 and 30.8 cm in female respectively. 3. The maximum growth curves were expressed by the equations; Y=9.212 In(X+1)+0.025 in male and Y=11.953 In(X+1)+0.025 in female when X is age in month and Y is length in cm. 4. It was revealed that female grew more rapidly than male. The growth of length was rapid in initial 2~3 months and weigth gain was rapid in later than 2~3 months. The weight seems better than length as an indicator of aging.

Chemotherapeutic control of Enterobius vermicularis infection in orphanages.

Abstract: To observe the effect of egg-free state in an institute on the endemicity of Enterobius vermicularis, the theoretical condition was made by repeated chemotherapy. Mebendazole or pyrantel pamoate were administered to all orphans and their staffs concomitantly for four times, each 20-day interval. In two low endemic orphanages, in which mean egg positive rates were 18 % and 39 % respectively, the pinworm infection was controlled up to 6~7 months period. And other two highly endemic orphanages, with 70% and 55% of egg positive rates, were controlled up to 90th day after the first treatment. After then up to 7 months, the reinfection occurred, but the endemicity was brought down to about 20 % of egg positivity.

Microscopic theory of condensed phase chemical reactions. II. Configuration space equations

Abstract: Configuration space equations for the description of reactive pair dynamics are obtained from the pair phase space kinetic equations derived in the preceding paper. These configuration space equations are generalizations of the conventional ’’sink’’ Smoluchowski equations. In addition to displaying the modifications in Smoluchowski equation descriptions due to velocity relaxation effects, computationally tractable expressions for the diffusion and friction tensors are obtained. The structure of the rate kernel which follows from the phase space kinetic equation is also examined.

Thrombocytopenia and Altered Platelet Kinetics Associated with Prolonged Pulmonary-artery Catheterization in the Dog

Abstract: The authors studied platelet kinetics in healthy dogs subjected to pulmonary-artery (Swan-Ganz) catheterization. Ten dogs with a mean weight of 11.0 ± 1.12 kg (SD) were equally divided into experimental and control groups. A fraction of platelets from each dog was harvested, labelled with 51Cr, and reinfused. Daily blood samples for determinations of radioactivity and platelet count were obtained. From the third to fifth day after platelet labelling, experimental dogs underwent catheterization with Swan-Ganz catheters. During 48 hours following catheterization, platelet counts decreased 64.2 ± 15.2 per cent from baseline. There was no corresponding change in the control dogs. Calculated platelet survival times (based on decay in platelet radioactivity over time) were 102 ± 6.5 hours for the experimental group and 139.8 ± 16.3 hours for controls (P < 0.01). Postmortem examination of one sample dog demonstrated thrombus formation along the length of the catheter and in the pulmonary artery. Significant thrombocytopenia with decreased platelet survival is associated with the use of Swan-Ganz catheters in dogs. The mechanism has not been defined. This observation adds an important consideration to the interpretation of platelet kinetics observed in many pathologic states in animal models.

Can all elementary particle forces be unified at 100 --1000 TeV

Abstract: A modest proposal to deal with the gauge hierarchy problem is suggested by removing the necessary conditions for a huge ratio of vacuum expectation values. Instead of the grand unification at 10/sup 15/ GeV, we unify the electroweak and strong interactions at a low energy 100 --1000 TeV. The observed values of sin/sup 2/theta/sub W/ and ..cap alpha../sub s/ are used as inputs in the determination of the group in the SU(N) series. The currently favored values of sin/sup 2/theta/sub W/ and ..cap alpha../sub s/ put a limit on N> or =9. In this kind of grand unification, proton stability is a necessity for consistency.

A survey of the action of KoreanAngelica plants on drug metabolism

Abstract: Eight species of the genusAngelica in Korea were examined for the activity of affecting drug metabolism and for the presence of coumarins. The results showed that various parts, especially roots and fruits ofAngelica plants had strong effects on drug metabolism and that they contained various derivatives of coumarins.

Fine Structure of Cysticercus cellulosae from Human Brain

Abstract: A transmission electron microscopic study was conducted in order to know basic tegumental structure of Cysticercus cellulosae which was obtained from the ventricles of human brain. In general, the electron microscopic appearance of the tegument resembled that of the body wall of adult and larval forms of other cestodes. The tegument both of the parenchymatous portion (scolex and spiral canal) and bladder portion consisted of such components, i.e., an outer vesicular layer with microtriches, and an inner fibrous layer. The subtegumental tissue below the fibrous layer was filled with muscle bundles and tegumental cells. The surface of the larva was covered by the microtriches of two distictly different types. The characteristic pyramid-shaped "tetrahedral" form was observed on the surface of the scolex portion, whereas the elongated, slender "filamentous" microtriches were distributed on the regions of the spiral canal and bladder portion. The tegumental and subtegumental tissues varied in thickenss from one region to the next. The possibility of application in making differential diagnosis from other larval cestodes and possible fuction of this larval tegument were discussed.

Anomalous propagation of probability in quantum mechanics

Abstract: The initial-value problem of the force-free Schrodinger equation is solved in closed-form for initial wave functions which are constrained to a finite region of space and improper boundary conditions at infinity. It is shown that the wave function and probability density propagate with infinite speed into the space. This is explained mathematically to be due to the parabolic nature of the Schrodinger equation. It is concluded that the Schrodinger equation gives a qualitatively not quite satisfactory description of the (time-dependent) propagation of probability densities due to the occurrence of infinite propagation speeds.

Spectroscopic characterization of alpha-crustacyanin.

Abstract: alpha-Crustacyanin exhibits two CD extrema with negative and positive bands at 690 and 583 nm in phosphate buffer, respectively. The CD spectrum is interpreted in terms of dipoledipole coupling between the transition moments of the two astaxanthin molecules on each subunit. The CD splitting yields an exciton bandwidth of 2800 cm-1, corresponding to an inter-chromophore distance of ca. 13 A in which the two astaxanthin molecules exist in a dimeric array with a mutual orientation angle of ca. 90 degrees. The SDS denaturation completely abolishes the long wavelength CD splitting, while 2 M NaCl reduces the overall CD intensity without destroying the split CD spectrum. It is suggested that the characteristic CD extrema at 583 and 690 nm arise from the intra-subunit astaxanthin-astaxanthin coupling. The binding site for astaxanthin contains one or more tryptophan residues, as the tryptophan fluorescence is quenched by energy transfer from the tryptophan to the prosthetic group in the native form of the carotenoprotein. The strong red shift (lambda max 487 nm) is probably due to interactions between tryptophan residue(s) and the chromophore molecules through dipole-dipole or partial charge transfer forces.

Simple derivation of molecular-field theory with correlation

Abstract: We rederive the principal result of molecular-field theory with correlation, which was introduced recently by Mattis. The new derivation is simple and straightforward. The approximation involved in this formulation is also manifested clearly.

Natural mass scale and neutrino oscillation

Abstract: Two principles, the standard SU(2)/sub L/ x U(1) electroweak theory below 100 GeV and the natural mass scale, are suggested for studying possible connections between neutrino oscillation and a mass hierarchy above 100 GeV. Neutrino-oscillation parameters of order or approx. = 10/sup 8/--10/sup 9/ GeV. An SU(7) model in this scenario is described in some detail.

Selection criteria of subjects for drug evaluation in enterobiasis.

Abstract: When an antipinworm drug was evaluated in human being, the results are still variable according to authors. Among the various factors involved in these variable results, the selection of subjects must be one of them. In the past, in evaluating a drug, the subjects were simply anal swab positive cases in a population. By that kind of selection method, especially in low endemic population, anal swab positives spontaneously turned to egg negatives at random. Moreover, the time, frequency of negative conversion cannot be predicted. By the results, the cure rates obtained from such ill-defined subjects are variable according to the subjected population. Another problem is that evaluation should represent the efficacy in heavily infected cases. To reinforce and overcome such shortcomings, the evaluator shoud select the cases wha are infected with whole developmental stages of worm. And the evaluator should have a method selecting such ideal cases only with anal swabs. To find out such method the results of anal swabs of long-term follow-up without any antipinworm treatment were reevaluated. In 41 children from 6 orphanages of different endemicity, swabs were taken for 8 or 21 times during 36 or 91 days. The positive rate of follow-up swabs was compared with that of already obtained in 4 preliminary swabs. And we collected other data on the combination of 4 anal swab results in different endemicity. The results are as follows: 1. The positive rate of follow-up swabs was significantly different by the consecutiveness of egg positivity in preliminary swabs as well as the endemicity of subjected population. The consecutively positive cases in higher endemicity over 60% showed the highest, and the least variable positive rate in follow-up swabs. 2. The observed frequency of consecutively positive/consecutively negative combination was always higher than the expected one obtained by binomial distribution equation. This indicates that individual hygiene and previous infection are important factors in determining the actual occurrence of subsequent reinfection. Summarizing these results, the subjects for drug evaluation should be those of consecutively positive cases in population over 60% endemicity. These subjects have the lowest chance of spontaneous negative conversion at random period of follow-up swabs. Eligible cases for such criteria would be sufficiently secured in highly endemic population.

Screening of Korean medicinal plants for antitumor activity

Abstract: Potential antitumor activity of sixteen Korean medicinal plants was tested against leukemia SN 36, murine tumor model. Survival studies by measuring life span indicated thatMorus alba (Moraceae), Verbascum phlomoides (Scrophulariaceae), Curcuma longa (Zingiberaceae), Torilis japonica (Umbelliferae), Bupleurum falcatum (Umbelliferae) andCodonopsis pilosula (Campanulaceae) exhibited significant antitumor activity with the dose-schedule employed in the experiment. Methanol(70%) extracts ofPlatycodon grandiftorum (Campanulaceae), Bupleurum longeradiatum (Umbelliferae) andAsiasarum sieboldii (Aristolochiaceae) showed rather potent toxicity.

Mathematical description of drug distribution in the isolated organ

Abstract: The model of an isolated organ system has been constructed to simulate the behavior of drug in the circulatory system of an acting organ or site. The model is developed on the following assumptions: The drug in the microcirculatory system cannot permeate the capillary walls. The capillary bed is modeled as a simple ideal plug flow system with and without radial concentration gradient. The mathematical model is developed from basic considerations of drug distribution with hemodynamical and pharmacokinetical meanings.