$Sr_{1+x}Ho_{1-x}FeO_{4-y}$계의 비화학량론적 조성과 그 물성에 관한 연구

유광선,유광현,노권선,여철현,Kwang Sun Ryu,Kwang Hyun Ryu,Kwon Sun Roh,Chul Hyun Yo 대한화학회 1993 대한화학회지 Vol.37 No.11

$K_2NiF_4$형 구조를 갖는 $Sr_{1+x}Ho_{1-x}FeO_{4-y}$ (x = 0.00, 0.25, 0.50, 0.75 및 1.00) 고용체계를 대기압과 1550$^{\circ}$C에서 제조하였다. 이 시료들의 X-선 회절도는 전 x 영역에서 모든 시료와 결정학적 상이 정방정계임을 나타내고 있다. 격자부피는 $Sr^{2+}$ 이온이 치환되는 양이 증가함에 따라 계속적으로 증가한다. 전체 철이온에 대한$ Fe^{4+}$ 이온의 몰비인${\tau}$</TE>값은 시료의 Mohr 염 적정으로 결정하였으며 x값과 ${\tau}$</TE>값으로부터 산소비화학량인 y값을 계산하였다. ${\tau}$</TE>값과 y값은 x값의 증가에 따라서 증가함을 알 수 있었다. x값, ${\tau}$</TE>값 y값을 일반식 $Sr_{1+x}Ho_{1-x}Fe^3_{1-}\;^+_{\tau}Fe_{\tau}^{4+}O_{4-y}$에 대입하여 비화학량론적 화학식을 결정하였다. Mossbauer 스펙트라는 $Fe^{3+}$ 이온과 $Fe^{4+}$ 이온의 혼합원자가 상태와 배위상태를 나타낸다. 각 시료들의 자기적 성질은 상온에서 상자성임을 알 수 있다. 전기전도도는 1.0 ~ 1 ${\times}\;10^{-9}{\Omega}^{-1}cm^{-1}$의 범위의 반도체 영역에서 변한다. 전기전도도의 활성화 에너지는${\tau}$</TE>값이 증가함에 따라 감소함을 알 수 있다. 전도성 메카니즘은 $Fe^{3+}$ 와 $Fe^{4+}$ 이온간에 전도성 전자의 건너뜀 모델로 설명되어야 한다. The series of solid solutions in the $Sr_{1+x}Ho_{1-x}FeO_{4-y}$ (x = 0.00, 0.25, 0.50, 0.75 and 1.00) systems with $K_2NiF_4$ type structure have been prepared at 1550$^{\circ}$C under an atmospheric air pressure. The X-ray powder diffraction spectra of these samples assign that the crystallographic phases are tetragonal system over the whole x range. The lattice volume was increased with increasing the substitution amount of the $Sr^{2+}$ ion. The mole ratio of the $Fe^{4+}$ ion to total iron ions or ${\tau}$ value has been determined by Mohr salt titration of the sample and then the y value was calculated from x and ${\tau}$ values. The ${\tau}$ and y values have been increased with x values. The nonstoichiometric chemical formula are formulated from the general formula of $Sr_{1+x}Ho_{1-x}Fe^3_{1-}\;^+_{\tau}Fe_{\tau}^{4+}O_{4-y}$ replaced by x,${\tau}$ and y values. Mossbauer spectra show the mixed valence state and coordination state of $Fe^{3+}\;and\;Fe^{4+}$ ions. It is found out that the magnetic property of the samples is paramagnetic at room temperature. Electrical conductivity varied within the semiconductivity range of 1.0 to 1 ${\times}\;10^{-9}{\Omega}^{-1}cm^{-1}$. Activation energy of the electrical conductivity was decreased with the $\tau$ value. The conduction mechanism should be explained by the hopping model of the conduction electrons between the valence states of $Fe^{3+}\;and\;Fe^{4+}$ ions.

도핑온도에 따른 폴리아날린 필름의 전기전도도

유광선,여철현,Ryu, Kwang Sun,Yo, Chul Hyun 대한화학회 2001 대한화학회지 Vol.45 No.3

고집광 태양광 발전을 위한 렌즈 및 광 파이프 특성 시뮬레이션

유광선(Ryu Kwang-Sun),신구환(Shin Goo-Hwan),차원호(Cha Won-Ho),명로훈(Myung Noh-Hoon),김용식(Kim Young-Sik),정호윤(Chung Ho-Yoon),김동균(Kim Dong Kyun),강기환(Kang Gi-Hwan) 한국태양에너지학회 2011 한국태양에너지학회 학술대회논문집 Vol.2011 No.4

The artificial increase in the solar intensity incident on solar cells using lenses or mirrors can allow solar cells to generate equivalent power with a lower cost. In application areas of Fresnel lenses as solar concentrators, several variations of design were devised and tested. Some PV systems still use commercially available flat Fresnel lenses as concentrators. In this study, we designed and optimized flat Fresnel lens and the 'light pipe' to develop 500X concentrated solar PV system. We performed rigorous ray tracing simulation of the flat Fresnel lens and light-pipe. The lightpipe can play imporatant roles of redistributing solar energy at the solar cell and increase the mechanical tolerance so that it can increase the lifetime of the high-concentration solar PV system and decrease the cost of manufacturing. To investigate the sensitivity of the solar power generated by the concentrated solar PV according to the performance of lens and light pipe, we performed ray tracing and executed a simulation of electrical performance of the solar cell when it is exposed to the non-uniform illumination. We could conclude that we can generate 95 % or more energy compared with the energy that can be generated by perfectly uniform illumination once the total energy is given the same.

고집광 태양광 발전을 위한 광학시스템 렌즈 개발

유광선(Ryu Kwang-sun),차원호(Cha Won-ho),신구환(Shin Goo-hwan),조희근(Cho HeeKeun),김용식(Kim Young-sik),강성원(Kang Seong-won),강기환(Kang Gi-Hwan) 한국태양에너지학회 2011 한국태양에너지학회 논문집 Vol.31 No.2

The artificial increase in the solar intensity incident on solar cells using lenses or mirrors can allow solar cells to generate equivalent power with a lower cost. There are two types of concentration optics for solar energy conversion. One is to use mirrors, and the other is to use Fresnel lenses. The gains that can be achieved with a Fresnel lens or a parabolic mirror are compared. The result showed the gains are comparable and the two configurations were developed competitively. In application areas of Fresnel lenses as solar concentrators, several variations of design were devised and tested. Some PV systems still use commercially available flat Fresnel lenses as concentrators. A convex linear Fresnel lens to improve the concentration ratio and the efficiency is devised and flat linear Fresnel lens in thermal energy collection is utilized. In this study, we designed and optimized flat Fresnel lens and the ‘light pipe’ to develop 500X concentrated solar PV system. In the process, we compare the transmission efficiencies according to groove types. We performed rigorous ray tracing simulation of the flat Fresnel lenses. The computer aided simulation showed the ‘grooves in case’ has the better efficiency than that of ‘grooves out case’. Based on the ray-trace results we designed and manufactured sample Fresnel lenses. The optical performance were measured and compared with ray-trace results. Finally, the optical efficiency was measured to be above 75%. All the design and manufacturing were performed based on that InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. Field test will be made and analyzed in the near future.

혼합원자가 Sr$_{1+x}Er _{1-x} FeO _{4-y}$ 훼라이트계의 비화학양론과 물성연구

여철현,유광선,편무실,이성주,최중길,Chul Hyun Yo,Kwang Sun Ryu,Mu Sil Pyun,Sung Joo Lee,Joong Gill Choi 대한화학회 1991 대한화학회지 Vol.35 No.2

$K_2NiF_4$형 층상 구조를 갖는 Sr$_{1+x}Er _{1-x} FeO _{4-y}$계에서 x = 0.00, 0.25, 0.50, 0.75 및 1.00인 비화학양론적 화합물 고용체를 1350$^{\circ}$C 대기압에서 제조하였다. X-선 회절 분석결과로 모든 조성에서 고용체의 결정 구조는 준정방정계(pseudo-tetragonal system)였다. 비화학양론적 조성식은 Mohr염 분석으로 결정하였다. Fe$^{4+}$ 이온의 양은 x값이 0.50까지 증가함에 따라 증가하다가 다시 감소하였고 산소 비화학량은 증가하였다. 도한 시료의 Fe$^{3+}$와 Fe$^{4+}$의 혼합원자가 상태를 298K에서 Mossbauer 분광분석으로 확인할 수 있었다. 전기전도도 측정 결과에 따르면 전기전도도는 반도체 영역인 10-2 ∼ 10-7(${\Omega}$-1cm-1)범위에서 변하였고, 활성화에너지는 Fe$^{4+}$의 몰비인 ${\tau}$값이 증가함에 따라 감소하였다. 전기전도성 메카니즘은 Fe$^{3+}$와 Fe$^{4+}$의 혼합원자가 상태간의 전도성전자 건너뜀 모델로 설명할 수 있다. Nonstoichiometric solid solutions of Sr$_{1+x}Er _{1-x} FeO _{4-y}$ system (x = 0.00, 0.25, 0.50, 0.75 and 1.00) with layered $K_2NiF_4$ type structure were prepared at 1350$^{\circ}$C under atmospheric pressure. By the analysis of X-ray diffraction, the crystallographic structures of the solid solution of all compositions were found to be pseudo-tetragonal system. Nonstoichiometric chemical formulas have been determined by Mohr salt analysis. It shows that the amount of Fe$^{4+}$ increases with increasing x up to 0.50 and then decreases, and the value of oxygen nonstoichiometry increases with increasing x value. Mixed valency states of Fe$^{3+}$ and Fe$^{4+}$ in the sample were identified again by Mossbauer spectroscopic analysis at 298 K. Electrical conductivity varied within the semiconductivity range of 10-2 ∼ 10-7(${\Omega}$-1cm-1), activation energy for electrical conduction decreased with the increment of the mole ratio of Fe$^{4+}$ or ${\tau}$ value. The conduction mechanism could be explained by the hopping model of the conduction electrons between the valency states of Fe$^{3+}$ and Fe$^{4+}$.

FIMS 타입의 우주관측용 원자외선분광기 광학설계

선광일,육인수,유광선,이대희,SEON KWANG-IL,YUK IN-SOO,RYU KWANG-SUN,LEE DAE-HEE 한국천문학회 2004 天文學論叢 Vol.19 No.1

An imaging spectrograph concept optimized for extended far-ultraviolet emission sources is presented. Although the design was originally developed for FIMS aboard the first Korean science satellite STSAT-l launched on September 27, 2003, no rigorous theoretical background of the spectrograph design has been published. The spectrograph design employs an off-axis parabolic cylinder mirror in front of a slit that guides lights to a diffraction grating. The concave grating provides moderate spatial resolution over a large field of view. This mapping capability is absent in most astronomical instruments but is crucial to the understanding of the nature of a variety of astrophysical phenomena. The aberration theory presented in this paper can be extended to holographic gratings in order to improve the spatial as well as the spectral resolutions.

금속-산화막 반도체 전계효과 트랜지스터의 우주방사선에 의한 총이온화선량 시험을 위한 테스트 베드

신구환(Goo-Hwan Shin),유광선(Kwang-Sun Ryu),정성인(Sung-In Chung),강경인(Kyung-In Kang),김형명(Hyung-Myung Kim) 한국항공우주학회 2006 韓國航空宇宙學會誌 Vol.34 No.11

최근에 인공위성용 전자소자는 우주방사선에 좀 더 강한 소자를 요구되어진다. 왜냐하면, 인공위성의 수명과 기능은 우주방사선으로부터 영향을 받기 때문이다. 또한, 과거에는 부품단위의 우주방사선 시험을 수행하지 않고 유닛 또는 서브시스템 단위의 우주방사선 시험을 수행하였다. 게다가, 발사된 인공위성이 작동오류 상태에 있을 때 그 이유를 분석하기에는 그다지 쉬운 일은 아니다. 따라서, 발사 전 부품 단위 우주방사선 시험을 수행하여 주요 소자에 대한 우주방사선에 의한 영향을 분석 할 필요가 있으며, 지상에서 데이터를 확보할 필요가 있다. 그러므로, 본 논문에서는 모든 전자소자의 기본이라 할 수 있는 금속-산화막 반도체 전계효과 트랜지스터의 총이온화선량에 대한 영향 시험을 수행하기 위한 테스트 베드를 제안한다. Recently, all the electrical parts for sateIJite application are required more strong against cosmic rays, because spacecraft's life time and function are depending on the their conditions. Also, a TID effect test was undertaken with units and/or subsystems which are already assembled on the PCB in past time. However, it is very hard to know and analyze that some abnormal states are appeared after launch. Moreover, it is necessary to perform a test of TID effects based on the parts level for preparing preliminary data in cosmic rays. Therefore, this paper presents a test-bed to perform a TID effect test of Metal-Oxide Semiconductor Field Effect Transistor (MOSFET) which is a fundamental element for electronics.

구조물의 동적 문제에 대한 개선된 벌군집 알고리즘의 적용

박지용(Ji-Yong Park),류수필(Su-Pil Ryu),엄영섭(Young-Sop Eom),유광선(Kwang-Sun Yoo),박재용(Jae-Yong Park),한석영(Seog-Young Han) 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-

Modified artificial bee colony algorithm (ABCA) as one of swarm intelligence methods and finite element analysis are adopted for topology optimization for dynamic problems. The objective is to obtain the structure with the highest first or second natural frequency with a certain amount of material based on each element's contribution to the natural frequency. A few examples of 2D structural models are provided to examine the effectiveness and applicability of the proposed algorithm comparing with the results of the bi-directional evolutionary structural optimization (BESO) method. The following conclusions are obtained that the modified ABCA is well able to handle the dynamic optimization problems with a large number of design variables, it is found that the modified ABCA is robust and stable with the convergence criterion.

차세대 중형위성 3호 자기장 측정기(AIMAG) 열해석

황재민(Jae-Min Hwang),차원호(Won-Ho Cha),서정기(Joung-Ki Seo),유광선(Kwang-Sun Ryu),이승욱(Seung-Uk Lee),우창호(Chang-Ho Woo),장은진(Eun-Jin Jang),최두영(Dooyoung Choi),최정림(Cheong-Rim Choi) 한국항공우주학회 2022 한국항공우주학회 학술발표회 논문집 Vol.2022 No.11

嶺東地方과 嶺西地方의 氣象要素 比較

蘇鮮燮,柳光善 공주대학교 사범대학 과학교육연구소 1995 과학교육연구 Vol.26 No.1

氣候란 여러 氣候要素를 綜合的으로 나타낸 것이다. 그리고 氣候要素는 地形, 海拔高度, 海流 등의 여러 氣候因子에 의하여 決定이 된다. 본 硏究에서는 東海岸에 平行하게 뻗은 太白山脈을 境界로 嶺西地方과 嶺東地方의 氣候要素 差異를 20 년 간 月, 年平均하여 比較하고 氣候因子를 토대로 差異 原因을 分析하였다. 그 結果 太白山脈을 境界로 푀엔 現象, 東海岸을 흐르는 暖流의 影響 등으로 氣溫, 降水量, 蒸發量 등의 氣候要素 差異를 發見할 수도 있고 그로부터 相對濕度 差異를 알 수 있었다. 또한 摩擦力의 差異로 內陸보다는 海岸의 風速이 强한 것도 알 수 있었다. 또한 두 地域의 資料를 回歸分析을 통하여 變化量을 알아본 결과 風速, 嶺東의 蒸發量을 除外하고는 모든 要素가 약간씩 增加하는 것으로 나타났다. 아울러 우리 人間들의 무분별한 行動으로 인하여 환경 汚染이 深刻하다. 또한 그로부터 생기는 氣候變化에 좀더 많은 硏究가 필요하고 그 對策이 講究되어야 할 것이다. The climate is dependent on the particularities of such several meteorological elements as geographical features, height above the sea level, and the sea currents. This study focused on analyzing the differences of the climates between the Eastern and Western areas, which are devided by the TAEBAEK Mountains, paralleled with the Eastern seashore. The meteorological elements of the two areas are compared on the basis of the monthly and yearly mean. This study found the two areas showed the differences in the temperature, the amount of precipitation, the amount of evaporation, with the results of Foehn Phenomenon and a warm current in the East Sea. It also found that the two areas differed from each other in the relative humidity, and the velocity of the wind in the Eastern seashore was higher than that in the inland area, due to the difference in frictions. The meteorological data of the two areas were comparatively analyzed in a regression, and showed that all the climate elements, only with exceptions of the velocity of wind and the amount of evaporation in the Eastern area, have been increased and heightened. A further study is highly needed about the changes of meteorological elements, which seemed to have been resulted from the environmental pollution, due to the thoughtless behaviors of people. And it is sincerely hoped that wise measures against the meteorological elements changes should be worked out very soon.