작동중인 LED 내부 다중양자우물구조의 정량적 온도 분포 계측

정의한(Eui Han Jung),황광석(Gwangseok Hwang),권오명(Ohmyoung Kwon) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.5

Polarography에 依한 Nitrosophenylhydroxylamine에 關한 硏究

황정의,정종재,손무용,Jung-Eui Hwang,Chong-Jae Chung,Moo-Young Son 대한화학회 1969 대한화학회지 Vol.13 No.4

酸性溶液中에서 重金屬 이온의 沈澱劑로 널리 使用되는 Nitrosophenyhydroxylamine(Cupferron)의 非可逆電極反應의 電流電壓曲線과 酸性 및 알카리性에서의 還元反應機構 및 反應速度 그리고 pH變化에 따른 관여전자수, 活性化 energy를 Delahay 方法을 利用하여 구하였다. The ammonium salt of Nitrosophenylhydroxylamine "called cupferron", is a well-known analytical reagent, which precipitates a great number of metal ions in acid medium. The electrode reduction velocities of cupferron at droping mercury electrode in various supporting electrolytes were measured by Delahay method. The free energy of activation and transfer coefficient for a given electrode reaction are computed from the corresponding current-voltage curve. The number of electrons involved in the rate determining step of the reduction of cupferron is calculated for solutions of various pH.

성역할정체성, 삶의 지향성, 내적 통제성과 우유부단의 관계

황정의 ( Jung Eui Hwang ),이창환 ( Chang H. Lee ) 慶熙大學校 社會科學硏究院 2011 社會科學硏究 Vol.37 No.1

본 연구는 성역할 정체성, 삶의 지향성(낙관성, 비관성), 내적 통제성과 대학생의 우유부단 수준의 관계를 알아보기 위하여 실시되었다. 설문에 대한 응답을 상관, 단순회귀 분석, 중다 회귀 분석을 통해 검증한 결과 남성성이 높을수록, 낙관성이 높고, 비관성이 낮을수록, 내적통제성이 높을수록 우유부단의 수준이 낮았고 모두 유의미하였다. 또한 성역할정체성, 삶의 지향성, 내적통제성이 남녀 집단별 우유부단에 미치는 상대적 영향력을 알아본 결과 남자 대학생의 우유부단 전체와 우유부단의 하위 요인인 불안의심, 속도지연을 설명해주는 예언변인은 남성성, 낙관성, 여성성, 비관성의 순서였으며, 하위변인인 역기능성은 남성성, 비관성순으로 영향을 미치는 것으로 나타났다. 여자 대학생의 우유부단 전체를 가장 잘 설명해주는 예언 변인은 남성성, 비관성, 내적통제성순으로 영향을 미쳤으며 불안 의심은 남성성, 낙관성, 여성성, 내적통제성 순이었다. 속도지연을 가장 잘 설명해주는 예언 변인은 남성성, 비관성순이었으며 역기능성은 남성성, 비관성, 내적통제성 순으로 영향을 미쳤다. The purpose of this study was to investigate the relationship between indecisiveness and gender role identity(masculinity and feminity) and life orientation (dispositional optimism and pessimism) and the internal locus of control beliefs in order to identify potential risk factors for indecisiveness. The findings indicated that women participants reported more indecisiveness than men. The higher levels of masculinity, dispositional optimism and internal locus of control subjects reported, the lesser was the level of indecisiveness.

몇 가지 혼합용매 중에서 KCl의 선택적 용매화

황정의,김학성,차성극,박의환,Jung Ui Hwang,Hag Sung Kim,Seong Keuck Cha,Eui Hwan Park 대한화학회 1991 대한화학회지 Vol.35 No.5

전도도법을 이용하여 물과 물-유기용매계에서 몇 가지 이온들의 용매화수를 측정하였다. 용매화된 이온의 Stokes 반지름을 Nightingale 법으로 보정하였으며, 혼합용매계에서의 각 용매의 용매화수는 몇 가지 가정을 세워 산정하였다. 이와 같이 정한 용매화수는 이온의 선택적 용매화를 나타내었고 등용매화점을 이용하여 이온의 선택적 용매화 정도를 알아보았다. The solvation numbers of some ions in water and of KCl in mixed solvent systems were measured using the conductometric method. Stoke's radii of ions in solution were calibrated by the Nightingale method and the solvation numbers of ions in mixed solvents were deduced by simple assumptions. The deduced solvation numbers of each solvent reasonably go with its selective properties of solvation. From the isosolvation point of ions, the selective properties of ionic solvation were discussed.

작동중인 LED 내부 다중양자우물구조의 정량적 온도분포 계측을 통한 효율저하 현상의 원인 탐구

정의한(Eui Han Jung),황광석(Gwangseok Hwang),권오명(Ohmyoung Kwon) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

In developing the highly efficient light-emitting diode (LED), performance degradation due to the efficiency droop during the high power operation is a critical problem. In order to increase the external quantum efficiency (EQE) of LED devices by solving the efficiency droop, its origin should be identified first. The origin of efficiency droop is mentioned as Joule heating(1), non-radiative recombination of electron-hole pair(2), polarization mismatch(3), Auger recombination(4), and leakage current(5). However, it has not been accurately elucidated yet, because the most previous reports depends on the modeling results only. In this study, we quantitatively profile the temperature distribution on the cross section of the active layer of LED device in order to directly investigate the origin of the efficiency droop. By measuring the temperature profile at the various injection current densities with the spatial resolution of about 50nm, we track the hot spot, whose location is determined by the injection current density. Therefore, the origin of efficiency droop on the LED devices is characterized by locating hot spot ?non-radiative recombination center? with the increase of injection current.

電解質溶液의 粘度係數의 測定과 濃度關係에 對한 考察

사공열,황정의,Sakong, Yull,Hwang, Jung-Eui 대한화학회 1964 대한화학회지 Vol.8 No.1

전해질용액의 점도가 농도의 양수임은 기지의 사실이나 전농도에 걸쳐 잘 맞는 관계식은 아직 발견되지 않았다. 표면장력 역시 이러한 관계가 있으나 완전한 식은 없으며 이들은 모두 용액내의 이온의 상태에 기인하므로 표면장력과 덤도간에도 일정한 관계가 있을 것으로 생각되는 바이다. 순수한 물질에 대한 관계식은 Silverman1)이 Batchinski식 과 MacLeod 식에서 ${\gamma}^{\frac{1}{4}}=\;A/{\eta}$ + B 식을 유도하여 실험오차 범위안에서 일치된다고 했으나 아직 $Jones^{(4)}$들이 측정한 몇가지 염을 제외하고는 거의 모든 염용액의 점도나 표면장력의 정밀한 값은 측정되지 않았음으로 우선 여기서는 몇가기 염용액의 점도를 측정하였고 또 점도계수와 농도관계를 고찰하였다. The viscosities of strong electrolytic solutions, such as KCl, KI and NaI have been measured over a fairy wide range of concentration variation (from 0.00002 to 3.7M). It was hoped that a study of the data in the light of modern theories on solution might reveal new relation between viscosity and surface tension of electrolytic solution. To secure more accurate measurements of viscosity and surface tension of the solutions, Ostwald viscometer was made with pyrex glass and modified the timing system for the transit of the meniscus with a new electronics system and with a pulse counter. As the experimental data obtained were in good agreement with the Jone's values, Jones-Dole equations for the electrolytic solutions were deduced, ${\eta}KCl\;=\;1\;+\;0.0052{\sqrt{c}}\;-\;0.01612c\;+\;0.00808c^2\;at\;30^{\circ}C$ ${\eta}KI\;=\;1\;+\;0.0220{\sqrt{c}}\;-\;0.01290c\;+\;0.02988c^2\;at\;25^{\circ}C$${\eta}Na\; =\;1\;+\;0.0240{\sqrt{c}}\;-\;0.0640c\;+\;0.03268c^2\;at\;25^{\circ}C$Gruneisen effect appeared in the dilute solution, whereas anti-Gruneisen effect was found for the extremely dilute solution. No satisfactory interpretation for the variation of the viscosity with concentration can be found at the present.

선반 화물운송용 물류이송로봇의 개선된 주행알고리즘 연구

조재훈(Jae-Hoon Cho),정의황(Eui-Hwang Jung),김지연(Ji-Yeon Kim),박민홍(Min-Hong Park),김용태(Ynog-Tae Kim) 한국지능시스템학회 2018 한국지능시스템학회논문지 Vol.28 No.5

본 논문에서는 선반 화물운송용 물류이송로봇의 가중치 기반 우선순위 충돌회피 알고리즘과 SLAM 기반의 개선된 주행알고리즘을 제안한다. 물류센터 내에서의 다개체 물류이송로봇들은 개별 주행알고리즘을 기반으로 주행을 한다. 일반적으로 알려진 D*Lite 주행알고리즘에서는 여러 대의 물류이송로봇들이 있을 경우 다른 로봇들을 동적장애물로 인식하여 충돌을 피하기 위하여 다른 경로를 생성하여 주행한다. 또한 충돌이 예상되는 다른 로봇도 같은 방법으로 초기 주행경로를 수정하여 목적지로 주행을 한다. 그러나 빠르고 효율적인 물류처리를 위하여 보다 정확하고 효과적인 주행 알고리즘이 필요하다. 제안된 알고리즘은 주문순서와 처리 시간을 기반으로 우선순위를 선정하여 주행 효율성을 높였으며, SLAM 기술을 적용하여 주행 중 발생되는 오차를 최소로 하였다. 제안된 알고리즘의 성능을 검증하기 위하여 두 대의 선반이송용 물류이송로봇을 사용하였으며, 실험실 규모의 작업공간에서 주행 및 충돌회피 실험을 수행하였다. 실험결과에서 제안된 알고리즘이 기존 주행 알고리즘에 비하여 정확성 및 효율성이 우수함을 확인 하였다. In this paper, we propose a collision avoidance algorithm using weighted priority and an advanced traveling algorithm based on SLAM algorithm for logistics transportation robots that can transport the shelf. Multi-logistics transportation robots in a logistics center run on the basis of individual traveling algorithms. Generally, when several transportation robots exist, other robots are recognized as dynamic obstacles and D* Lite traveling algorithm generate different routes to avoid collision. Also, the robot, which is expected to collide, modify the initial moving route in the same way and travel to the destination. However, more accurate and effective traveling algorithm is needed for fast and efficient logistics processing. The proposed algorithm increases the traveling efficiency by selecting priorities based on the order number and processing time and minimizes the error that occurs during driving by applying SLAM technology. In order to verify the performance of the proposed algorithm, two transportation robots are used for transporting the goods and a traveling and collision avoidance experiment was performed in a laboratory size workspace. Experimental results show that the proposed algorithm shows better performance in accuracy and efficiency than the conventional algorithm.

주사탐침열파현미경 기반의 정량적 열전도도 계측기법을 이용한 Bi₂Te₃ 나노선의 열전도도 계측

박경배(Kyung Bae Park),황광석(Gwangseok Hwang),정의한(Eui Han Jung),권오명(Ohmyoung Kwon) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

Recently, the thermal characterization at nanoscale plays a key role in developing the high-performance thermoelectric materials and electric devices based on the nanomaterials. Although various thermal characterization methods at nanoscale have been reported, it is difficult to find the quantitative measurement results; thermal bridge method is difficult to obtain the thermal conductivity quantitatively due to the disturbance by thermal contact resistance between the heater and material; Raman spectroscopy has the diffraction-limited spatial resolution, which is about 1 ?m, so that it is not suitable for nano-materials and - devices. Herein, we develop the thermal characterization technique for measuring the thermal conductivity of the nanomaterials by utilizing the scanning thermal wave microscopy (STWM), which enables to measure the phase lag and amplitude of thermal waves quantitatively with nanoscale spatial resolution. By comparing the measured phase lag with the theoretical result, one can obtain the quantitative thermal conductivity. Since STWM utilize the relative difference between the measured phase lags of the thermal wave at high frequency, the disturbance due to the thermal contact resistance can be ignored. In this study, we quantitatively measure the thermal conductivity of the Bi₂Te₃ nanowire, which is widely studied in developing the high-performance thermoelectric materials, on the Si₃N₄/Si substrate with the newly developed thermal characterization method based on STWM.

고지방식이로 고지혈증이 유도된 흰쥐에서 황화된 수용성 β-glucan의 항고지혈증 효과

김용현(Yong Hyun Kim),한국일(Kook-Il Han),전미애(Miae Jeon),황선구(Seon Gu Hwang),정의길(Eui-Gil Jung),권현정(Hyun-Jung Kwon),한만덕(Man-Deuk Han) 한국생명과학회 2014 생명과학회지 Vol.24 No.11

본 연구는 영지버섯 균사체로부터 얻은 수용성 베타글루칸(SBG)이 고지방식이로 유도한 흰쥐의 항고지혈 효과 및 혈중 지질수준에 미치는 영향을 조사하였다. 5주령의 수컷 흰쥐에 고지방식이를 2주간 급여하여 비만을 유도하고, 그 후 2주 동안 다음과 같은 5가지 group의 식이를 급여하였다: 1) 일반사료 식이군(NC), 2) 고지방사료식이군(HC), 3) 고지방사료 및 고농도(200 mg/kg) SBG 식이군(HC-HSBG) 4) 고지방사료 및 저농도(20 mg/kg) SBG 식이군(HC-LSBG), 5) 고지방사료 및 로바스타틴(lovastatin) 식이군(HC-Lov). 실험 결과, 식이 효율(Food efficiency ratio)은 고지방식이를 급여한 군들에서 일반사료 식이군에 비하여 증가하였으나 통계적 유의성은 없었다. 혈액학적 결과에서 고농도 및 저농도의 SBG와 로바스타틴 투여군은 고지방식이만 급여한 군(HC)보다 호중구와 중성구 수치가 유의성 있게 증가하였다. 또한 혈청 내 총콜레스테롤, 중성지질 및 LDL-C는 고농도 및 저농도 SBG 투여군 모두에서 유의성 있게 감소되었다. 이 같은 결과는 화학적으로 황화된 수용성 베타글루칸(SBG)이 흰쥐에서 혈중 콜레스테롤 수치를 낮추어 항고지혈증 효과를 나타내는 것을 의미한다. The aim of this study was to investigate the effect of water-soluble sulfated β-glucan (SBG) obtained from Ganoderma lucidum mycelia on the antihyperlipidemic and serum lipid levels in high-fat diet-induced obese rats. Five-week-old male Sprague-Dawley rats were fed a high-fat diet for two weeks to induce obesity. They were ten divided into five groups-normal control diet group (NC), high-fat control diet group (HC), high-fat diet and 200 mg/kg of SBG group (HC-HSBG), high-fat diet and 20 mg/kg of SBG group (HC-LSBG), and high-fat diet and 20 mg/kg of lovastatin group (HC-Lov)-and fed one of five diets for two more weeks. Although food intake and final body weight after four weeks of SBG consumption were similar in the five experimental groups, food efficiency ratio was higher in the high-fat diet groups(2, 3, 4, and 5) than in the NC group. In evaluating the hematological parameters of the rats, the neutrophil and monocyte ratios were higher in the HC-HSBG, HC-LSBG, and HC-Lov groups than in the HC group. Serum lipid profiles were analyzed after a 12 hr fast at the end of the study. Total cholesterol, triglyceride, and low-density lipoprotein cholesterol (LDL-C) levels were significantly lower in the HC-HSBG and HC-LSBG groups than in the HC group. These results suggest that chemically engineered sulfated mushroom β-glucan (SBG) might contribute to lower cholesterol and lipid levels in blood.

광귤나무(Citrus aurantium) 열매에서 분리된 쿠마린의 iNOS 억제효과

김범선(Beom sun Kim),정의길(Eui Gil Jung),윤형선(Hyung Sun Youn),황경아(Kyung A Hwang),한만덕(Man Deuk Han),유연호(Yon ho Yu),남궁우(Kung Woo Nam) 대한약학회 2017 약학회지 Vol.61 No.5

Citrus fruits have been used as an edible fruit, and also as a traditional medicine, since ancient times. A crude methanol extract of Citrus aurantium was shown to suppress inducible proinflammatory cytokines, but its constituents were not known. In this study, we isolated four furanocoumarins, bergapten (1), imperatorin (2), isoimperatorin(3), and phellopterin (4), and one 7-geranyloxycoumarin, auraptene (5), from a methanol extract of dried Citrus aurantium fruit. The structures of these compounds were elucidated by extensive application of spectroscopic techniques, including 2D NMR spectroscopy and mass spectrometry. All of the isolated compounds were evaluated for their ability to inhibit the production of proinflammatory cytokine inducible nitric oxide synthase (iNOS) in lipopolysaccharide-activated RAW264.7 cells. Compounds 2−5 significantly suppressed iNOS production but compound 1 had no iNOS inhibitory effects. These results indicate that at least three furanocoumarins and one 7-geranyloxycoumarin are involved in the suppressive effects of citrus fruits against the production of inducible inflammatory cytokines.