Showing papers by "Pusan National University published in 1990"
TL;DR: In this article, a Brabender plasticoder was used to extract morphological properties of polypropylene(PP)/nylon-6, PP/nylon 6/(maleic anhydrideg-polypropylene-(MAH-g-PP)) and (MAHg-g,PP) blends.
94 citations
TL;DR: A new gamma-lactone derivative named davallialactone and the 7-O-beta-D-glucuronide of (+/-)-eriodictyol have been isolated from Davallia mariessi Moore using two-dimensional nuclear magnetic resonance (2D NMR) techniques.
Abstract: A new gamma-lactone derivative named davallialactone (4) and the 7-O-beta-D-glucuronide of (+/-)-eriodictyol (5a) have been isolated from Davallia mariessi Moore along with caffeic acid (1), 4-beta-D-glucopyranosylcaffeic acid (2) and 4-O-beta-D-glucopyranosyl-p-coumaric acid (3). The structures of the new compounds were determined by chemical and spectroscopic methods including two-dimensional nuclear magnetic resonance (2D NMR) techniques, especially 1H-detected heteronuclear multiple-bond multiple-quantum coherence and long-range C-H J-resolved 2D NMR techniques.
80 citations
TL;DR: In this paper, the equivalence of approximate controllability for a nonlinear system and a linear system with uniformly bounded nonlinear term was proved for a parabolic equation in a Banach space, where Bf(t) corresponds to a finite-dimensional control.
Abstract: We consider a control system for a parabolic equation in a Banach space with uniformly bounded nonlinear termF,
$$dz(t)/dt + Az(t) = F(t, z(t)) + Bf(t), t > 0.$$
Here,Bf(t) corresponds to a finite-dimensional control. We prove the equivalence of approximate controllability for the above nonlinear system and that for the linear system
$$dz(t)/dt + Az(t) = Bf(t), t > 0.$$
Our method is based on results on approximate controllability for linear parabolic systems and estimates of solutions. A practical example is also given for a diffusion and reaction model.
54 citations
TL;DR: A software release problem based on four software reliability growth models (SRGMs) with random life-cycle length is studied and the optimal values of release times are shown to be finite and unique.
Abstract: A software release problem based on four software reliability growth models (SRGMs) with random life-cycle length is studied. Test of the software system is terminated after time T and released (sold) to the user at a price. The price of the software system and three cost components are considered, and average total profit is used as a criterion. The optimal values of release times are shown to be finite and unique. Hence, the optimal solutions can be obtained numerically by, for example, a bisection method. A numerical example indicates that the optimal release time increases as (1) the error rate in each model decreases and (2) the difference between the error fixing cost during the test phase and that during the operational phase increases. The case of unknown model parameters is considered only for the Jelinski-Moranda model because a Bayes model is not available for other SRGMs. The release decision depends on testing time, but other stopping rules, for example based on the number of corrected errors, can be considered. >
48 citations
TL;DR: A 2:1 mixture of chlorotrimethylsilane and sodium nitrite or nitrate was found to be very effective for deoximation in this paper, which can also be successfully performed by t-butyl nitrite and CHS.
41 citations
TL;DR: In this article, it was shown that if every weakly compact convex subset of E has the fixed point property for nonexpansive mappings and 0 ϵ R(A), then the strong limt → ∞xt exists and belongs to A−10.
39 citations
TL;DR: In this article, the Sado-Pohang Belt was inferred to have formed during early Miocene to early Middle Miocene time and migrated southward along the south side of the Yamato Ridge in Paleogene time.
32 citations
TL;DR: Results indicate that cadmium intoxication impairs various Na(+)-amino acid cotransport systems in the renal brush border membrane, which leads to panaminoaciduria.
32 citations
TL;DR: In this article, the authors showed that intraperitoneal administration of methanolic extract of Ixeris dentata whole plants and its main component, cynaroside produced a significant hypoglycemic effect.
Abstract: Blood glucose and total lipid levels in rats with streptozotocin-induced diabetes were determined after intraperitoneal administration of methanolic extract ofIxeris dentata whole plants and its main component, cynaroside (=luteolin 7-O-β-D-glucoside). From the data obtained, it was concluded that intraperitoneal administration of the methanolic extract produced a significant hypoglycemic effect. Total blood lipids were also decreased. Cynaroside in the streptozotocin-diabetic rats failed to exhibit hypoglycemic effect but a significant hypolipemic activity was observed. Thus, it is suggested that this methanolic extract may contain one or more hypoglycemic and hypolipemic principles including the main flavone glucoside, cynaroside, which can significantly reduce the levels of triglyceride and total cholesterol in streptozotocin-diabetic rats.
25 citations
TL;DR: The SPMV isolated by the modified procedure of Smith and Loh showed the highest purity and the specific activities of Na, K-ATPase, acetylcholinesterase and 5′-nucleotidase were about 5.6-fold, respetively, enriched in the plasma membrane fraction.
Abstract: Synaptosomal plasma membrane vesicles (SPMV) were isolated from fresh bovine cerebral cortex by several well-known procedures, and the best procedure was selected by enzymatic and morphological standards. The SPMV isolated by the modified procedure of Smith and Loh showed the highest purity. The specific activities of Na, K-ATPase, acetylcholinesterase and 5′-nucleotidase were about 5.6-fold, 2.5-fold and 3.3-fold, respetively, enriched in the plasma membrane fraction as compared to those of the crude homogenate. Electron microscopic examination also showed that the membranes were in vesicular form.
25 citations
TL;DR: In this paper, the properties of two polyesters, poly(ethylene terephthalate) (PET) and bisphenol A-50/50 isophthalic/terephthalic acid based polyarylate (PAR), and their 85/15, 50/50, and 30/70 (PET/PAR) blends were investigated using a RDS rheometer, 290-310°C.
Abstract: Rheological properties of two polyesters; poly(ethylene terephthalate) (PET) and bisphenol A-50/50 isophthalic/terephthalic acid based polyarylate (PAR), and their 85/15, 50/50, and 30/70 (PET/PAR) blends were investigated using a RDS rheometer, 290–310°C. Measurements included complex viscosity and modulus. Activation energy for flow and relaxation spectrum were subsequently calculated. Results indicated that PET/PAR blends are rheologically incompatible, i.e., zero-shear viscosities of the blends showed a negative deviation from the averages of the two homopolymers with a sharp minimum at 85/15 composition. The relaxation spectrum for 85/15 blend also showed a relaxation plateau, a characteristic of rigid particle suspension. The morphology of the polymer blends was examined from cryogenically fractured and etched surface using a scanning electron microscopy (SEM). Morphological observation indicated that PAR-rich phases, order of 0.1μm, were finely dispersed in PET phase for 85/15 blend, whereas the dispersion of PET phase in PAR-rich phase was in spherical form, order of 0.5μm in diameter, for the 50/50 blend.
TL;DR: In this article, a binary blend of ethylene vinyl alcohol copolymers with nylons (nylon-6, nylon-6/12, and nylon-12) have been prepared from melt mixing in a twin screw compounding machine.
Abstract: Binary blends of ethylene vinyl alcohol copolymers, containing 62 (EVOH-62) and 71 (EVOH-71) mole percent vinyl alcohols, with nylons (nylon-6, nylon-6/12, and nylon-12) have been prepared from melt mixing in a twin screw compounding machine. Morphological, thermal, rheological, and mechanical properties were determined. EVOH-62/nylon-6 and EVOH-71/nylon-6 blends showed homogeneous phase morphologies in the nylon-6-rich region, and fine phase separations (c.a. 2 × 10−7 m) in the EVOH-rich region. Melting point depression, positive deviations in viscosity and flexural modulus, and negative deviation in impact strength from the simple additive rule were generally observed. And the results were possibly interpreted in terms of compatibility and increased nylon/EVOH interactions over the nylon/nylon interactions. On the contrary, clean phase separations in large domains were observed from EVOH-71/nylon-6/12 and EVOH-71 /nylon-12 blends. Fibrillation was also obtained from EVOH rich blends. Probably due to the incompatible nature of these blends, yield at low rate of shear and a mechanical property drop were also observed.
TL;DR: In this paper, the authors give several new characterizations of 2-inner product spaces and strict convexity for linear 2-normed spaces in terms of orthogonalites and 2-semi-inner products.
Abstract: In this paper, we give several new characterizations of 2-inner product spaces and strict convexity for linear 2-normed spaces in terms of orthogonalites and 2-semi-inner product spaces.
TL;DR: In this article, from the stem of Plrunus davidiana, naringenin and its glucoside, kaempferol and its corresponding glucosides, dihydrokaempferols and its derivatives, hesperetin, quercetin, d-catechin, β-sitosterol and β-glucoside were isolated.
Abstract: From the stem ofPrunus davidiana, naringenin and its glucoside, kaempferol and its glucoside, dihydrokaempferol, kaempferide glucoside, hesperetin glucoside, quercetin glucoside, d-catechin and β-sitosterol glucoside were isolated.
TL;DR: The CT findings of adenocarcinoma of the urachus in three patients were reviewed and correlated with pathologic features, finding the tumor was composed of two parts: supravesical and intravesical.
Abstract: The CT findings of adenocarcinoma of the urachus in three patients were reviewed and correlated with pathologic features. The tumor was composed of two parts: supravesical and intravesical. The supravesical portion showed a cystic appearance with a capsule in the space of Retzius. The intravesical portions invading the dome of the bladder were polypoid and unencapsulated. These findings were consistent with pathologic findings in all three patients.
TL;DR: In this article, the authors investigated a practical assessment procedure to evaluate the safety and reliability of ships on the basis of the ultimate longitudinal strength of ship's hull girder by using an existing rule of classification society.
Abstract: An attempt is made to investigate into a practical assessment procedure to evaluate the safety and reliability of ships on the basis of the ultimate longitudinal strength of ship's hull girder.The external bending moment acting on the hull girder is assumed by using an existing rule of classification society. The ultimate longitudinal strength is analyzed by idealized structural unit method, in which a structural model for plate element subjected to biaxial load is formulated by idealizing the actual nonlinear behaviour of the element taking account of the influence of initial imperfections as well as the interaction effect between the local and overall buckling of the structure. The central safety factor of the hull girder is evaluated by dividing the external bending moment into the ultimate bending moment. The reliability assessment is made by using Cornel's second-moment method.The proposed safety and reliability assessment procedure is then applied as an example to evaluate the central safety factor and the safety index of a double skin tanker. The influence of initial deflection, welding residual stress and the yield stress on the safety and reliability of the hull girder under sagging and hogging moment is investigated. The stiffening effect of the longitudinal girder and side stringer is also discussed.
01 Jan 1990
TL;DR: Transient Liquid Insert Metal Diffusion Bonding (TLIM bonding) as mentioned in this paper consists of three processes, viz., a dissolution process of base metal, an isothermal solidification process and a homogenizing process.
Abstract: Transient Liquid Insert Metal Diffusion Bonding (TLIM bonding) consists of three processes, viz., a dissolution process of base metal, an isothermal solidification process and a homogenizing process. These processes are considered theoretically based on results of current researches.
TL;DR: In this paper, the first order Raman spectra and their temperature dependence of lead molybdate single crystals (PbMoO4) have been measured using Argon ion laser(= 5145A) as exciting radiation source.
Abstract: The first order Raman spectra and their temperature dependence of lead molybdate single crystals(PbMoO4) have been measured using Argon ion laser(= 5145A) as exciting radiation source. We obtained 13 Raman active modes which are in good agreement with the results of group theory, but 170 cm−1 mode of Ag is found at Ag + Bg scattering geometry at room temperature. Intensities of Ag, Bg and Eg modes decrease rapidly as temperature increases; Ag modes and Bg and Eg modes disappeared at 700 °C and 600 °C respectively but we did not find the soft mode related to any phase transition.
TL;DR: There was a fairly good correlation between the local anesthetic activities and the microviscosity-lowering activities of these drugs, which suggests that the nerveblocking activity of local anesthetics might have some relation with their activity fluidizing the lipid bilayer of biomembrane.
Abstract: The microviscosities of the lipid bilayers of liposomal membranes of phospholipids were measured by the intermolecular excimer, formation method employing pyrene as a fluorescence probe, and the effects ofn-alkanols and other local anesthetics on the microviscosity were investigated. The results showed that then-alkanols and the other local anesthetics effectively lowered the microviscosity of the lipid bilayer of the dipalmitoyl phosphatidycholine liposomal membrane in proportion to the concentration of the additives. Moreover, there was a fairly good correlation between the local anesthetic activities and the microviscosity-lowering activities of these drugs. This results suggests that the nerveblocking activity of local anesthetics might have some relation with their activity fluidizing the lipid bilayer of biomembrane.
TL;DR: In this paper, the performance of a high-level (e.g., 16, 64 and 256-QAM) QAM system in the presence of Gaussian thermal noise combined with a non-Gaussian impulsive noise and cochannel continuous wave interference in the multipath fading environment is analyzed.
Abstract: An analysis is presented for the performance of a high-level (e.g. 16, 64 and 256-QAM) QAM (quadrature amplitude modulation) system in the presence of Gaussian thermal noise combined with a non-Gaussian impulsive noise and cochannel continuous wave interference in the multipath fading environment. The system performance is evaluated in terms of CNR (carrier-to-noise power ratio), CIR (carrier-to-interference ratio), impulsive index of the noise, power ratio of the Gaussian noise-to-impulsive noise, and fading figure. >
TL;DR: In this paper, the thermodynamic parameters of 1:1 complexes between lanthanide cations and pyrazinecarboxylate have been determined by calorimetric titration in the ionic medium of 1.0 M NaClO 4, aqueous solution at 25°C.
01 Jan 1990
TL;DR: In this paper, the transverse photothermal beam-deflection technique was used to study the phase transition of gadolinium molybdate (GMO) and tri-glycine sulfate (TGS) single crystals.
Abstract: The transverse photothermal beam-deflection technique is used to study the phase transition of gadolinium molybdate(GMO) and tri-glycine sulfate(TGS) single crystals. The phase transition temperatures obtained from the magnitudes and phase angles of the signal are in excellent agreement with the published values.
TL;DR: The single crystal of BiNbO4 was grown by Czochralski technique and determined its crystallographic axes at room temperature as discussed by the authors and the optimum conditions for pulling and rotation speeds were 1.2mm/hr and 15 rpm respectively at 1,130 °C.
Abstract: The single crystal of BiNbO4 was grown by Czochralski technique and determined its crystallographic axes at room temperature. The optimum conditions for pulling and rotation speeds were 1.2mm/hr and 15 rpm respectively at 1,130 °C. BiNbO4 was found to undergo two phase transitions at 562 °C and 470 °C from temperature dependence measurements of dielectric constants and Raman spectra were studied for X(ZZ)Y, X(YX)Y, X(YZ)Y geometries.
TL;DR: In this article, the authors investigated the ferroelastic domain switching behavior by employing the stress-strain hysteresis curves in BiVO4 crystal grown by the Czochralski method.
Abstract: The ferroelastic domain switching behaviour has been investigated by employing the stress-strain hysteresis curves in BiVO4 crystal grown by the Czochralski method. When a small stress is applied the domain walls which are (110)A and (110)B twin planes move and return to the initial positions as the stress is removed. This switching behaviour is found to be strongly influenced by the rate of strain, and may be explained by the restricted rotation of the VO4 tetrahedron in the distorted scheelite structure. The switching stress of 2.6 × 106 N/m2 is experimentally determined by progressively raising the strain. The value turns out to be in good agreement with 2.3 ∼ 3.6 × 106 N/m2 calculated from the elastic constants of BiVO4.
TL;DR: In this article, the physical properties of rare earth vanadate (RVO4) ceramics synthesized with hot-pressed method were studied and it has been reported that RVO4 and RAsO4 undergo the ferroelectric-paraelectric phase transition at room temperatures.
Abstract: We have studied the physical properties of the rare-earth vanadate (RVO4) ceramics synthesized with hot-pressed method. It has been reported that RVO4 and RAsO4 undergo the ferroelectric-paraelectric phase transition at room temperatures. We have found a possibility that there is another phase transition near 240K for various RVO4 from the dielectric constant measurement.
TL;DR: In this paper, the stabilization effect of α-tocopherol incorporated into liposomal phospholipid membrane was investigated by fluorospectrophotometry and UV-visible spectrogotometry.
Abstract: The stabilization effect of α-tocopherol incorporated into liposomal phospholipid membrane was investigated by fluorospectrophotometry and UV-visible spectrophotometry. The release of entraped carboxyfluorescein from liposomes was markedly retarded by the presence of α-tocopherol in the bilayer of liposomal phospholipid membrane relative to cholesterol-containing liposomes and pure phospholipid liposomes. α-tocopherol-containing liposomes prolonged the oxidation of liposomes-embedded heme as an oxygen carrier. The oxidation index of α-tocopherol-containing liposomes was lower than those of cholesterol-containing liposomes and pure phospholipid liposomes. Thus α-tocopherol-containing liposomes may be useful for the carrier systems of nutrients and drugs to phospholipid bilayer and stabilized liposomes.
TL;DR: In this article, the authors measured dielectric constants for various Bi(1 -x)GdxVO4 ceramics and found an additional anomaly in dielectic constant for rare earth vanadates (RVO4: R = Eu, Gd etc).
Abstract: BiVO4 is a ferroelctric material below 255°C. Recently the rare-earth vanadates (RVO4: R = Eu, Gd etc) have been proved to be ferroelectrics below room temperature. In this study, we measure dielectric constants for various Bi(1 -x)GdxVO4 ceramics. We find an additional anomaly in dielectic constant. The phase diagram is suggested.
18 Jun 1990
TL;DR: In this paper, a vibrating sample magnetometer was used to measure the magnetic critical fields of Bi1.4Pb0.6Ca2Sr2Cu3Oy superconductor with Tc=108 K and Hc2(0) in a temperature range of about 15 K below Tc, and the temperature dependence of Hc 2 is obtained from the onset of diamagnetism.
Abstract: Magnetization measurements were performed on Bi1.4Pb0.6Ca2Sr2Cu3Oy superconductor with Tc=108 K using a vibrating sample magnetometer in fields up to 18 kOe. The magnetization M(T) is linearly increased in a temperature range of about 15 K below Tc, and the temperature dependence of Hc2 is obtained from the onset of diamagnetism. From the upper critical field slope ∂Hc2/∂T, the zero-temperature upper critical field Hc2(0) is estimated about 61 T. Also, the lower critical field Hc1(0) is 111 Oe using the magnetization measurement M(H). From the magnetic critical fields Hc2 and Hc1, we estimate the superconducting parameters: the coherence length ζ0=23 A, the penetration depth λ0=2600 A, the Ginzburg-Landau parameter κ=113 and the jump in the specific heat ΔC/Tc2 mJ/molK2.
TL;DR: In this article, the modification of the phases in the mixed ceramics of BiVO4 and GdVO4 has been studied with x-ray diffraction and Raman scattering experiments.
Abstract: The modification of the phases in the mixed ceramics of ferroelastic BiVO4 and ferroelectric GdVO4 has been studied with x-ray diffraction and Raman scattering experiments. We observe evidences that a new phase in addition to BiVO4 and GdVO4 phases exists in the mixed ceramics for 0.3 ≤ × ≤ 0.9. Additional peaks in the x-ray diffraction patterns and new Raman modes are observed.