Cyclic Voltammetry를 이용한 CuInSe₂ 박막의 전기화학적 전착 연구

홍순현,이현주,김양도,Hong, Soonhyun,Lee, Hyunju,Kim, Yangdo 한국재료학회 2013 한국재료학회지 Vol.23 No.11

Chalcopyrite $CuInSe_2$(CIS) is considered to be an effective light-absorbing material for thin film photovoltaic solar cells. CIS thin films have been electrodeposited onto Mo coated and ITO glass substrates in potentiostatic mode at room temperature. The deposition mechanism of CIS thin films has been studied using the cyclic voltammetry (CV) technique. A cyclic voltammetric study was performed in unitary Cu, In, and Se systems, binary Cu-Se and In-Se systems, and a ternary Cu-In-Se system. The reduction peaks of the ITO substrate were examined in separate $Cu^{2+}$, $In^{3+}$, and $Se^{4+}$ solutions. Electrodeposition experiments were conducted with varying deposition potentials and electrolyte bath conditions. The morphological and compositional properties of the CIS thin films were examined by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The surface morphology of as-deposited CIS films exhibits spherical and large-sized clusters. The deposition potential has a significant effect on the film morphology and/or grain size, such that the structure tended to grow according to the increase of the deposition potential. A CIS layer deposited at -0.6 V nearly approached the stoichiometric ratio of $CuIn_{0.8}Se_{1.8}$. The growth potential plays an important role in controlling the stoichiometry of CIS films.

Perceptual Influence of Non-Spectral Cues on Spectral Properties of Korean Vowel Signals in Seoul Corpus: A Neural Network Modeling Study

Soonhyun Hong(홍순현) 현대문법학회 2019 현대문법연구 Vol.102 No.-

Though the importance of spectral characteristics of Korean vowels in the hVd syllable has been recognized in the literature, it has never been studied whether static spectral measurements at a (steady-state) central section are enough to characterize Korean vowels in spontaneous speech, or dynamic spectral measurements across the temporal dimension can better characterize vowels. Despite ample reported evidence of the perceptual influence of non-spectral cues on spectral properties of vowels in the literature, no reports have yet been released on the difference in the degree of the perceptual influence of non-spectral cues (e.g., place and manner of the preceding or following phones, F0, speaking rate, prosody, and gender) on spectral properties of vowels. Through Neural Network pattern recognition modeling in a supervised mode, it was found that dynamic spectral models with non-spectral cues better explain vowel perception than static spectral models and furthermore, flanking phone identities, and manner and place of flanking phones are perceptually the most influential while duration, F0 and speaking rate are perceptually far less contributive than argued in the literature.

/n/-insertion in native Korean and Sino-Korean revisited

Soonhyun Hong(홍순현) 한국음운론학회 2006 음성·음운·형태론 연구 Vol.12 No.2

  Korean /n/-insertion is reanalyzed in this paper: e.g. /n?c-y?l?m/ [n?nny?r?m] ‘late summer’ in native Korean and /sik+yoŋ+yu/ [sikyoŋnyu] ‘cooking oil’ in Sino-Korean. There are two critical problems for the analysis of this phenomenon. First, /n/ is not an unmarked consonant in Korean. /t/ is reserved as an unmarked consonant (Kim 1987). Second, /n/-insertion is observed between a consonant and y in both native Korean and Sino-Korean. However, as native Korean and Sino-Korean have different morphology, it has been difficult to analyze the two sublexical aspects of /n/-insertion in a uniform way. For example, the insightful analyses of native Korean /n/-insertion (Kang 1992, Han 1994b, and Cho 1995a) equipped with the native Korean morphology-based Prosodic Word Formation, do not work in Sino- Korean /n/-insertion. This is because Sino-Korean has totally different morphology. This paper tries to address these problems and argues that a uniform analysis of the two sublexical aspects of /n/-insertion is possible in the framework of Optimality Theory.

[n]-Insertion in the Kyungsang Dialect

Soonhyun Hong(홍순현) 새한영어영문학회 2005 새한영어영문학회 학술발표회 논문집 Vol.2005 No.5

칼슘 도핑을 통한 고 에너지 밀도를 가지는 Ni-rich 층상 구조형 양극 소재의 안정화

강범희,홍순현,윤홍관,김도진,김천중,Kang, Beomhee,Hong, Soonhyun,Yoon, Hongkwan,Kim, Dojin,Kim, Chunjoong 한국재료학회 2018 한국재료학회지 Vol.28 No.5

Lithium-ion batteries have been considered the most important devices to power mobile or small-sized devices due to their high energy density. $LixCoO_2$ has been studied as a cathode material for the Li-ion battery. However, the limitation of its capacity impedes the development of high capacity cathode materials with Ni, Mn, etc. in them. The substitution of Mn and Ni for Co leads to the formation of solid solution phase $LiNi_xMn_yCo_{1-x-y}O_2$ (NMC, both x and y < 1), which shows better battery performance than unsubstituted $LiCoO_2$. However, despite a high discharge capacity in the Ni-rich compound (Ni > 0.8 in the metal site), poor cycle retention capability still remains to be overcome. In this study, aiming to improve the stability of the physical and chemical bonding, we investigate the stabilization effect of Ca in the Ni-rich layered compound $Li(Ni_{0.83}Co_{0.12}Mn_{0.05})O_2$, and then Ca is added to the modified secondary particles to lower the degree of cationic mixing of the final particles. For the optimization of the final grains added with Ca, the Ca content (x = 0, 2.5, 5.0, 10.0 at.%) versus Li is analyzed.

산화구리의 광전기화학적 거동 특성

윤홍관,홍순현,김도진,김천중,Yun, Hongkwan,Hong, Soonhyun,Kim, Dojin,Kim, Chunjoong 한국재료학회 2019 한국재료학회지 Vol.29 No.1

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide($Cu_2O$) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of $Cu_2O$ is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of $Cu_2O$ while imperfections of the $Cu_2O$ thin films are removed. This study investigates the photoelectrochemical properties of $Cu_2O$. However, severe photo-induced corrosion impedes the use of $Cu_2O$ as a photoelectrode. Two candidates, $TiO_2$ and $SnO_2$, are selected for the passivation layer on $Cu_2O$ by by considering the Pourbaix-diagram. $TiO_2$ and $SnO_2$ passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that $SnO_2$ is a good passivation layer for $Cu_2O$.

산화니켈 및 탄소나노튜브/산화니켈 복합체 가스센서의 제작과 황화수소 감지 특성

양하늘,박지환,홍순현,윤홍관,김천중,김도진,Yang, Haneul,Chinh, Ngyuen Duc,Hieu, Ngyuen Minh,Park, Jihwan,Hong, Soonhyun,yun, Hongkwan,Kim, Chunjoong,Kim, Dojin 한국재료학회 2018 한국재료학회지 Vol.28 No.8

Nickel oxide(NiO) thin films, nanorods, and carbon nanotube(CNT)/NiO core-shell nanorod structures are fabricated by sputtering Nickel at different deposition time on alumina substrates or single wall carbon nanotube templates followed by oxidation treatments at different temperatures, 400 and $700^{\circ}C$. Structural analyses are carried out by scanning electron microscopy and x-ray diffraction. NiO thinfilm, nanorod and CNT/NiO core-shell nanorod structurals of the gas sensor structures are tested for detection of $H_2S$ gas. The NiO structures exhibit the highest response at $200^{\circ}C$ and high selectivity to $H_2S$ among other gases of NO, $NH_3$, $H_2$, CO, etc. The nanorod structures have a higher sensing performance than the thin films and carbon nanotube/NiO core-shell structures. The gold catalyst deposited on NiO nanorods further improve the sensing performance, particularly the recovery kinetics.

DC, pulse 조건에 따른 구리 도금층 미세 조직 관찰

윤지숙,박찬수,홍순현,이현주,이승준,김양도,Yoon, Jisook,Park, Chansu,Hong, Soonhyun,Lee, Hyunju,Lee, Seungjun,Kim, Yangdo 한국재료학회 2014 한국재료학회지 Vol.24 No.2

The aim of this work was to investigate the effects of electrodeposition conditions on the microstructural characteristics of copper thin films. The microstructure of electroplated Cu films was found to be highly dependent on electrodeposition conditions such as system current and current density, as well as the bath solution itself. The current density significantly changed the preferred orientation of electroplated Cu films in a DC system, while the solution itself had very significant effects on microstructural characteristics in a pulse-reverse pulse current system. In the DC system, polarization at high current above 30 mA, changed the preferred orientation of Cu films from (220) to (111). However, Cu films showed (220) preferred orientation for all ranges of current density in the pulse-reverse pulse current system. The grain size decreased with increasing current density in the DC system while it remained relatively constant in the pulse-reverse pulse current system. The sheet resistance increased with increasing current density in the DC system due to the decreased grain size.

마그넬리상 합성과 광전기화학셀 전극 응용

박지환,양하늘,홍순현,김천중,김도진,Park, Jihwan,Nguyen, Duc Quang,Yang, Haneul,Hong, Soonhyun,Truong, Thi Hien,Kim, Chunjoong,Kim, Dojin 한국재료학회 2018 한국재료학회지 Vol.28 No.5

Hydrothermal synthesis of highly crystalline $TiO_2$ nanorods is a well-developed technique and the nanorods have been widely used as the template for growth of various core-shell nanorod structures. Magneli/CdS core-shell nanorod structures are fabricated for the photoelectrochemical cell (PEC) electrode to achieve enhanced carrier transport along the metallic magneli phase nanorod template. However, the long and thin $TiO_2$ nanorods may form a high resistance path to the electrons transferred from the CdS layer. $TiO_2$ nanorods synthesized are reduced to magneli phases, $TixO_{2x-1}$, by heat treatment in a hydrogen environment. Two types of magneli phase nanorods of $Ti_4O_7$ and $Ti_3O_5$ are synthesized. Structural morphology and X-ray diffraction analyses are carried out. CdS nano-films are deposited on the magneli nanorods for the main light absorption layer to form a photoanode, and the PEC performance is measured under simulated sunlight irradiation and compared with the conventional $TiO_2/CdS$ core-shell nanorod electrode. A higher photocurrent is observed from the stand-alone $Ti_3O_5/CdS$ core-shell nanorod structure in which the nanorods are grown on both sides of the seed layer.

평생학습 권역 설정과 권역별 프로그램 요구분석

조대연(Cho, Daeyeon),김영호(Kim, Youngho),홍순현(Hong, Soonhyun),김벼리(Kim, Byuri) 한국평생교육학회 2011 평생교육학연구 Vol.17 No.1

본 연구의 목적은 마포구 내 평생교육기관과 학습자를 중심으로 학습서비스의 수요와 공급을 고려하여 학습서비스 권역을 설정하고 권역별 평생학습 프로그램 요구를 분석함으로써 권역별 특성화된 평생교육 프로그램을 제안하기 위함이다. 이를 위하여 먼저 평생학습 서비스의 수요와 공급 관련 지표를 활용한 지리정보시스템을 이용하여 권역설정을 한 결과 마포구는 ‘자연, 레크리에이션’, ‘실버학습’, ‘비경제인구학습’, ‘ITㆍ문화산업’, ‘일반학습’, ‘소수ㆍ소외계층 학습’ 등 총 6개 권역으로 구분되었다. 또한 조대연(2009)의 연구를 활용하여 각 권역별 프로그램 요구분석을 실시한 결과 자연ㆍ레크리에이션 권역이 가장 다양한 프로그램요구를 보였고, ITㆍ문화산업 권역이 상대적으로 낮은 평생교육프로그램의 요구를 보였다. 또한 마포구의 학습서비스 권역별 평생교육 프로그램으로 예체능계열과 인문계열 평생교육 프로그램에 대한 높은 요구를 보였다. 연구 결과를 바탕으로 몇 가지 시사점을 제안하였다. The purpose of this study is two fold: to determine learning service regions based on the demand and supply of lifelong learning from the aspect of lifelong learners and lifelong learning institutes and to implement the setting of priorities among lifelong learning programs through need analysis according to the identified learning service regions in Mapo-Gu. With utilizing an index of the demand and supply regarding lifelong learning service, Geographic information system found out that 6 regions can be identified in Mapo-Gu. Through the process proposed by Cho(2009), this study finally determines the lifelong learning programs that were ranked as the highest priorities in each region. As a result, 'nature & recreation' region shows the most variety of program needs, whereas 'IT & cultural industry' region shows relatively less variety of program needs. In addition, this study found that Mapo-Gu has the high level of needs on humanities programs as well as arts & physical ones. Finally, this study suggests not only the direction of developing programs based on each region but also specified programs from the results of need analysis. Also this study proposes some practical implications.