Pukyong National University

About: Pukyong National University is a education organization based out in Busan, South Korea. It is known for research contribution in the topics: Phosphor & Luminescence. The organization has 6689 authors who have published 14681 publications receiving 233751 citations. The organization is also known as: PKNU.

Solution-processed small-molecule organic solar cells based on diketopyrrolopyrrole and perlyene derivatives with coplanar structures

Abstract: A series of small-molecules (SMs) based on coplanar perylene unit coupled with diketopyrrolopyrrole chromophoric core exhibit broad absorption in the range of 500–800 nm and low bandgap energise of...

Epitaxial strain dependent electrocatalytic activity in CaRuO3 thin films

Abstract: The systematic tunability of electrocatalytic activity is indispensable not only for realizing highly efficient catalysts but also for understanding the underlying mechanism of chemical reactions at the surface. Epitaxial strain is a powerful tool for tailoring various physical and chemical properties of perovskite transition metal oxides, including electrocatalytic activity. We present single-crystalline CaRuO3 epitaxial thin films as a model system, in which the oxygen evolution reaction was systematically controlled by the epitaxial strain. With an increase in the degree of tensile strain, the interband transition energy and hybridization strength within the Ru–O bond decreased, which enhanced the oxygen evolution reaction. Our study facilitates the understanding of the correlation between the lattice/electronic structure and the electrocatalytic activity, which might be applied to other transition metal oxide catalysts.

Radiometric Calibration and Uncertainty Analysis of KOMPSAT-3A Using the Reflectance-Based Method.

Abstract: In recent years, Korea has sustained consistent access to remote sensed data by launching Korea Multi-Purpose Satellite-3A (KOMPSAT-3A, K3A)-an updated version of the high-resolution KOMPSAT series. This KOMPSAT-3A required calibration and validation (Cal/Val) before and after its launch to enable proper functional characterization and to maintain the veracity of data collected. The Korea Aerospace Research Institute (KARI) executed the initial prelaunch calibration in the laboratory and we performed the Cal/Val of KOMPSAT-3A during the Launch and Early Operation Phase (LEOP) in the field. Two suitable sites in Korea and Mongolia with stable weather, almost uniform terrain, and near Lambertian diffusion, provided the necessary tarp reflectance to calculate the absolute radiometric calibration coefficients. The surface reflectance was determined using 12 and four well-calibrated reference reflectance tarps employing the FieldSpec® 3(Analytical Spectral Devices Inc., Boulder, CO, USA) Spectroradiometer. Subsequently, the top of atmosphere (TOA) radiance was estimated using radiative transfer code (RTC) software based on the Atmospheric and Topographic Correction (ATCOR). In addition, cross calibration was simultaneously performed at the Libya-4 pseudo invariant calibration site (PICS) for KOMPSAT-3A TOA radiance, using the spectral band adjustment factor (SBAF) compensated Landsat 8 reflectance and the Second Simulation of Satellite Signal in the Solar Spectrum (6S) to compute cross calibration coefficients. The results of the KOMPSAT-3A absolute calibration coefficient show that the R2 values were over 0.99, implying a significant correlation for almost all bands between the TOA radiance and the KOMPSAT-3A spectral band response at both campaign sites. However, this study reveals a difference of less than 5% calibration gains for all bands compared to the prelaunch values, while the cross calibration gain is below 5% in visible bands and above 5% in the near infrared band. An effort to optimize the reliability of the absolute calibration coefficients resorted to the rigorous quantification of uncertainties amongst atmospheric conditions, the digital number (DN), the reflectance tarp, the bidirectional reflectance distribution function (BRDF), and ozone levels. Therefore, we presumed that the total uncertainty was 4.27%, which conforms to some published results.

Optimum Installation of Permeable Pavement Using Multi-Objective Optimization Technique

Abstract: 도시화에 따른 불투수 면적의 증가는 강우유출수의 양적 증 가 뿐 만 아니라 무강우 기간에 노면에 축적되는 오염물질의 양도 증가시켜 도시하천의 비점오염원 관리에 대한 사회적인 관심을 촉발시켰으며, 최근 저영향개발(Low Impact Development, LID)의 개념 도입까지 추진하고 있다. LID는 자연에 미치는 영향을 최소화하면서 도시개발을 추진하는 개념으로, 수생태 분야에서는 생태적으로 건전한 소규모 비점저감시설 을 배수분구 전역에 전략적으로 분산 배치하여 비점오염원을 관리하는 것을 목적으로 한다(Cho et al., 2013). 비점오염저감을 위하여 LID 개념을 도입한 연구사례를 살 펴보게 되면, Park et al.(2015a)은 비점오염저감시설 중 하나 인 식생저류지의 최적 설계용량을 산정하는 연구를 진행하였 Abstract

Development of Low-Noise Small-Area 24 GHz CMOS Radar Sensor

Abstract: We present a low-noise small-area 24 GHz CMOS radar sensor for automotive collision avoidance. This sensor is based on direct-conversion pulsed-radar architecture. The proposed circuit is implemented using TSMC 0.13 μm RF (radio frequency) CMOS ( GHz) technology, and it is powered by a 1.5 V supply. This circuit uses transmission lines to reduce total chip size instead of real bulky inductors for input and output impedance matching. The layout techniques for RF are used to reduce parasitic capacitance at the band of 24 GHz. The proposed sensor has low cost and low power dissipation since it is realized using CMOS process. The proposed sensor showed the lowest noise figure of 2.9 dB and the highest conversion gain of 40.2 dB as compared to recently reported research results. It also showed small chip size of 0.56 mm2, low power dissipation of 39.5 mW, and wide operating temperature range of −40 to +125°C.