CuS/CdS 박막제작과 태양전지로의 응용

최용대 牧園大學校 1986 論文集 - 牧園大學校 Vol.11 No.-

CdS polycrystalline thin films were deposited on the ITO substrate by the chemical bath deposition method. Cu₂(CuS)S/CdS heterojunction thin film solar cell formed on CdS thin films using a chemical reaction method. The maximum short-circuit current, open-circuit voltage, fill factor, and energy conversion efficiency of Cu₂(CuS)S/CdS heterojunction thin film solar cells obtained at 80 mW/cm² were found to be 6.2mA/cm², 0.3V, 0.44 and 1.03%, respectively.

HWE법으로 성장한 ZnMnSe 단결정 박막의 특성

최용대 한국물리학회 2003 New Physics: Sae Mulli Vol.47 No.6

Zn$_{1-x}$Mn$_x$Se epilayers have been grown on GaAs (100) substrates by hot-wall epitaxy. The structure of the epilayers was found to be zincblende over a large Mn composition range, 0 $\leq$ x $\leq$ 0.75, and the relation between the Mn composition x and the lattice constants was found to be consistent with the Vegard law. Exciton-related near-edge emissions and the intra-Mn$^{2+}$ transition were observed in the 5 K photoluminescence spectrum. The composition dependence of PL peak energy was also studied. It was found weak bowing effect at near x $\sim$ 0. Hot-wall epitaxy법으로 Zn$_{1-x}$Mn$_x$Se 단결정 박막을 GaAs(100) 기판 위에 성장하였다. 단결정 박막의 구조는 Mn의 조성비 x가 넓은 범위인 0 $\leq$ x $\leq$ 0.75에서 섬화아연 구조이고 Vegard 법칙을 만족함을 알았다. 저온 광발광 스펙트럼에서 엑시톤 관련 발광 피크와 intra-Mn$^{2+}$ 천이 피크가 관측되었다. 또한 발광 피크 에너지의 Mn 조성에 따른 의존성이 연구되었고, x $\sim$ 0 근처의 작은 조성비 영역에서 약한 휨(bowing) 효과를 관측하였다.

스트레인을 받는 ZnTe/ZnMnTe 단일양자우물의 성장과 광발광 특성

최용대 한국결정성장학회 2002 韓國結晶成長學會誌 Vol.12 No.6

ZnTe/ZnMnTe single quantum well of high quality was grown by hot-wall epitaxy, in which ZnMnTe layer was used as a barrier. It was found that ZnTe well layer was under severe strain. Very sharp luminescent peaks of the heavy-hole exciton (el-hhl) and the light-hole exciton (el-lhl) were observed from the photoluminescence (PL) measurement. As the well layer thickness increases, the peaks associated with excitons of (el-hhl) and (el-lhl) were shifted toward the lower energy side. The temperature dependence of the PL peak intensity was well explained by the thermal activation theory. 희박 자성 반도체 ZnMnTe를 장벽층으로 사용한 양질의 ZnTe/ZnMnTe 단일 양자우물 구조를 열벽적층 성장법으로 성장하였다. 고분해능 X-선 회절측정 결과 ZnTe 우물층이 강하게 스트레인을 받고 있음을 알 수 있었다. 광발광 측정으로부터 무거운 양공 엑시톤 (el-hhl)과 가벼운 양공 엑시톤 (el-lhl)의 매우 뾰족한 발광 크들이 나타남을 관측하였다. 또한 우물층의 두께가 증가함에 따라 (el-hhl)과 (el-lhl)의 엑시톤 관련 피크들은 낮은 에너지 쪽으로 이동하였다. 광발광 피크 세기의 온도에 따른 변화는 운반자들의 열적 활성화로 설명할 수 있었다.

GaAs(100)기판 위에 성장된 $Zn_{0.86}Mn_{0.14}Te$에피막의 띠 간격 에너지

최용대,안갑수,이광재,김성구,심석주,윤희중,유영문,김대중,정양준 한국결정성장학회 2003 韓國結晶成長學會誌 Vol.13 No.3

본 연구에서는 두께가 0.7 $\mu \textrm{m}$인 $Zn_{0.86}Mn_{0.14}$Te 에피막을 GaAs(100) 기판 위에 열벽 적층 성장하였다. 선택에칭용액에 의하여 GaAs 기판이 제거된 X-선 회절 패턴으로부터 $Zn_{0.86}Mn_{0.14}$Te에피막의 결정구조는 zincblende 이었으며 격자상수는 6.140 $\AA$으로 계산되었다. 이러한 격자상수 값과 Vegard 법칙으로부터 Mn의 조성비 x=0.14임을 알았다. 성장된 에피막의 결정성은 이중결정요동 곡선의 반폭치 값이 256 arcsec인 것으로부터 양호하다는 것이 확인되었다 상온에서 10K 까지 $Zn_{0.86}Mn_{0.14}$Te에피막의 온도에 따른 띠 간격 에너지를 측정하기 위하여 투과 스펙트럼으로부터 흡수 스펙트럼이 얻어졌다 온도가 감소할수록 흡수 스펙트럼에서 강하게 흡수가 일어나는 영역은 에너지가 큰 쪽을 향하여 이동하였고 흡쑤단 근처에서 자유 엑시톤 형성을 의미하는 흡수 피크가 생겨났다. $Zn_{0.86}Mn_{0.14}$Te에피막의 온도에 따른 자유 엑시톤 피크 에너지로부터 OK와 300 K일 때 띠 간격 에너지는 각각 2.4947 eV와 2.330 eV로 구하여졌다. 10 K에서 기판이 제거된 $Zn_{0.86}Mn_{0.14}$Te 에피막의 흡수 스펙트럼의 자유 엑시톤 피크 에너지는 광발광 피크 에너지보다 15.4 meV 정도 크다. 이 에너지 차이는 흡수 스펙트럼과 발광 피크 사이의 에너지 차이를 의미하는 Stokes shift를 나타낸다. In this study, $Zn_{0.86}Mn_{0.14}$Te epilayer of 0.7 $\mu\textrm{m}$-thickness was grown on GaAs(100) substrate by using hot wallepitaxy. GaAs(100) substrate was removed from $Zn_{0.86}Mn_{0.14}$Teepilayer by the selective etching solution. The crystal structure and the lattice constant of only Z $n_{0.86}$ M $n_{0.14}$Te epilayer were investigated to be zincblende and 6.140 $\AA$ from X-ray diffraction pattern, respectively. Mn composition x of $Zn_{1-x}Mn_x$Te epilayer was found to be 0.14 using this lattice constant and Vegard's law. The crystal quality of the epilayer was confirmed to be very good due to 256 arcsec-full-width at half-maximum of the double crystal rocking curve. The absorption spectra from the transmission ones were obtained to measure the band gap energy of $Zn_{0.86}Mn_{0.14}$Te epilayer from 300 K to 10 K. With the decreasing temperature,. strong absorption regions in the absorption spectra were shifted to higher energy side and the absorption peak meaning the free exciton formation appeared near the absorption edge. The band gap energy values of $Zn_{0.86}Mn_{0.14}$Te epilayer at 0 K and 300 K were found to be almost 2.4947 eV and 2.330 eV from the temperature dependence of the free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer, respectively. The free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer without GaAs substrate was larger 15.4 meV than photoluminescence peak position energy at 10 K. This energy difference between two peaks was analysed to be Stokes shift.

배드민턴 라켓용 Sheath/core 복합구조 String의 제조 및 특성

최용대,박영미,Choi, Yong-Dae,Park, Young-Mi 한국섬유공학회 2015 한국섬유공학회지 Vol.52 No.5

This paper presents a method of preparing a high-strength sheath/core complex badminton string and examines its playability and durability performance. From repeated experiments at the laboratory scale, it was determined that the tensile characteristics of sheath/core complex strings are better than those of widely used general strings. The key process of braiding, in which the string is prepared by twisting sheath multifilament around the core of a 3-ply monofilament, and the time required for applying a thin layer of coating, have decisive effects on the physical properties. The yarn diameter was found to be optimal when the string was coated three times and the structure of the sheath/core was composed of multifilament 1890d/monofilament 100d. SEM identified an increase in the inner thickness of the sheath/core string with braiding and coating. To conclude, Sample D displayed high tenacity, tensile extension, and tensile strength, which can affect durability, while its tensile modulus was the lowest (54.13 g/tex), which is indicative of good playability.

시간속성과 주기(週期)에 따른 경기(經氣).오유혈(五兪穴) 변화에 대한 연구

최용대,김병수,강정수,Choi, Yong-Dae,Kim, Byoung-Soo,Kang, Jung-Soo 대전대학교 한의학연구소 2010 한의학연구소 논문집 Vol.19 No.1

In Neijing("內經"), it explains heaven, earth, four seasons(天地四時) take part in human's birth, it gives influence on life support, and have organic relationship between body and movement of sun and earth(日月運行) of heaven and earth. Human body and the natural world corresponds, so the time changes in the natural world give immediate influence to human body, and correspond changes happen inside human body. This has no exception in qi of human(人氣), meridians, the viscera and organs(臟腑) and so on. In time, there are many kinds of cycles such as year, month, 10 days and a day. Yin and yang and the five elements in each cycle shows changes of prosperity and decay and transformation. In a year, there are spring, summer, late summer, fall and winter which are each included to wood, fire, earth, metal and water. Spring and summer belong to yang(陽), and fall and winter belong to yin(陰). A day can be divided into the crowing of the cook, dawn, noon, and twilight. After midnight yin falls and yang rises(陰盡陽生), and after noon yang falls and yin rises(陽盡陰生). Ups and downs of the qi and blood and human body change with time and the region of whereabout is different. In one month, when the moon is full qi of blood rises and when the moon comes down qi of blood falls. The qi of meridian(經氣) has a periodical changes with regular movement in meridian. This is a result of continuing movement of meridian and the nutrient(營) and the defense(衛) in human body, stars correspond with ups, and correspond with flow of water of meridian(經水) with downs. In a day the twelve meridians(十二經脈) in hour of yin(hours 3~5), it starts with qi and blood of lung meridian(手太陰肺經) prosperous, each qi and blood of meridian prosperous in order. In eight extra meridians(奇經八脈), Bideungpalbup(飛騰八法) per 5 days, Younggoopalbup(靈龜八法) per 60 days qi of pulse(脈氣) changes correspond. The qi and blood of five meridian points(五兪穴) is 5 days, so.

Platform for Manipulating Polarization Modes Realized with Jones Vectors in MATHEMATICA

최용대,김보경,윤희중 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.2

The fundamental conception in physics of the propagation of the electromagnetic wave polarization in matter is newly understood as the cardinal keyword in free-space quantum communication technology and cosmology in astrophysics. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has accordingly received attention from scientists exploiting the protocol of quantum key distribution (QKD) to guarantee unconditional security in cryptography communication. We have provided a dynamic polarization platform for presenting the polarization modes of a transverse electromagnetic wave, converting the state of polarization through the arrangement of optical elements, using Jones vectors calculations in Methematica. The platform graphically simulates the mechanism of production and propagation of the polarized waves in a medium while satisfying Maxwell's equations.

Vectorial Polarization Modes Platform Realized with Jones Vectors in Mathematica

최용대,윤희중 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.5

The fundamental concept in physics of polarization propagation of electromagnetic waves is newly understood to be a cardinal keyword in quantum cryptography transport technology and the Standard Model. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has received attention recently from scientists in the age of information and communication. This study presents a new dynamic polarization platform that presents the polarization modes of a transverse electromagnetic wave by using Jones vectors calculations in the symbolic program Mathematica to convert the state of polarization through the arrangement of the optical elements. The platform simulates a propagation process that satisfies Maxwell’s two vector equations precisely with the vectorial nature of the electromagnetic wave.

Visualizing Electromagnetic Vector Fields in Matter using MATHEMATICA

최용대,윤희중 한국진공학회 2019 Applied Science and Convergence Technology Vol.28 No.3

The quantities of dynamic physics including gravitational field and electromagnetic field are accurately described using vector differential operators. Electromagnetism is notably more conceptual in matter compared to vacuum because abstract, three-dimensional fields that are sometimes difficult to visualize are involved in most analysis. A visual representation of abstract vector fields in matter is invaluable to students or researchers working in this field and may also assist teachers in teaching electromagnetism to physics or engineering students. We successfully visualized the most fundamental concepts of the electromagnetic vector calculated and estimated using vector differential operators in Mathematica. This visualization based on vector calculations can be used as a starting platform for the further exploration of electromagnetic vector fields.

폐쇄성황달에 대한 전산화단층촬영술의 진단적 의의

최용대 대한영상의학회 1982 대한영상의학회지 Vol.18 No.4

Computed tomographic (CT) scans of 46 jaundiced patients were studied to determine the value of CT in the diagnosis of biliary pathology. All of the 12 cases of medical jaundice had positive CT correlation. Of the 34 cases of proven surgical jaundice, 97.8% were correctly identified by CT. In detecting the level of obstruction, the cases were divided into four groups by anatomical segments, according to the number of visualized low density ringlike structures produced by dilated bile duct. All of the correctly diagnosed surgical jaundice was 91.2%. The presence of stones or mass, the level of obstruction and the relative size and shape of visualized distal ring had proved to be the most important variables in etiological diagnosis of surgical jaundice. The results indicate that CT is useful and highly accurate in differenting between surgical (obstructive) jaundice and medical (non-obstructive) ajundice, and determining the level of obstruction and the etiology of surgical jaundice.