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Ha, M.H.,Choi, J. Elsevier Science B.V 2008 Environmental toxicology and pharmacology Vol.25 No.3
In this study, a preliminary characterization of the multiplicity of Chironomus hemoglobin (Hb) was conducted on the larvae of Chironomus tentans Mg. (Diptera: Chironomidae) by the molecular mass and isoelectric point. In order to identify Chironomus Hb as potential biomarker of environmental contamination, alteration of individual Hb by exposure to environmental chemicals, namely, nonylphenol, benzo[a]pyrene, chloropyriphos and cadmium chloride, were evaluated. To validate the ecotoxicological relevance of Chironomus Hb as a potential biomarker, ecotoxicity test using growth rate as toxic endpoint was also conducted. This study revealed a striking heterogeneity in C. tentans Hb; 10 Hb isoforms were observed in the larvae of 4th instar C. tentans by their molecular mass and by their isoelectric point. Chemical-induced alteration of individual Hb expression suggests that C. tentans Hb can be a target molecule for chemical exposure. Overall results suggest that the expression pattern of Hb proteins may potentially contribute to the development of a biomarker for ecotoxicity monitoring in C. tentans.
Helicity-dependent photocurrent in a Bi2Se3 thin film probed by terahertz emission spectroscopy
Hamh, Sun Young,Park, Soon-Hee,Jerng, Sahng-Kyoon,Jeon, Jae Ho,Chun, Seung-Hyun,Lee, Jong Seok American Physical Society 2016 Physical Review B Vol.94 No.16
<P>We investigate photocarrier dynamics in a Bi2Se3 thin film via terahertz (THz) emission spectroscopy. We report amplitude and phase modulations of the emitted THz wave under the variations in a polarization of an input laser beam and sample azimuth. Photon-helicity-dependent responses are manifested in both time and frequency domains, and azimuth dependence of such circular anisotropy exhibits a clear threefold periodicity. We analyze these results based on the symmetry of the bulk and the surface of Bi2Se3 and demonstrate that the observed helicity-dependent photocurrent originates from the circular photon drag effect, namely, linear and angular momentum transfers from photons to photocarriers.</P>
Hamh, Sun Young,Park, Soon-Hee,Han, Jeongwoo,Jeon, Jeong Heum,Kahng, Se-Jong,Kim, Sung,Choi, Suk-Ho,Bansal, Namrata,Oh, Seongshik,Park, Joonbum,Kim, Jun Sung,Kim, Jae Myung,Noh, Do Young,Lee, Jong Seo Springer US 2015 NANOSCALE RESEARCH LETTERS Vol.10 No.1
<P>We investigate the surface states of topological insulator (TI) Bi<SUB>2</SUB>Se<SUB>3</SUB> thin films grown on Si nanocrystals and Al<SUB>2</SUB>O<SUB>3</SUB> substrates by using terahertz (THz) emission spectroscopy. Compared to bulk crystalline Bi<SUB>2</SUB>Te<SUB>2</SUB>Se, film TIs exhibit distinct behaviors in the phase and amplitude of emitted THz radiation. In particular, Bi<SUB>2</SUB>Se<SUB>3</SUB> grown on Al<SUB>2</SUB>O<SUB>3</SUB> shows an anisotropic response with a strong modulation of the THz signal in its phase. From x-ray diffraction, we find that the crystal plane of the Bi<SUB>2</SUB>Se<SUB>3</SUB> films is inclined with respect to the plane of the Al<SUB>2</SUB>O<SUB>3</SUB> substrate by about 0.27°. This structural anisotropy affects the dynamics of photocarriers and hence leads to the observed anisotropic response in the THz emission. Such relevance demonstrates that THz emission spectroscopy can be a sensitive tool to investigate the fine details of the surface crystallography and electrostatics of thin film TIs.</P>
S. Y. Hamh,한정우,김태헌,이종석 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.2
Complex-valued optical constants of thin films can be determined in various ways, such as polarization changes upon grazing reflection and simultaneous measurements of the reflectance (R)and the transmittance. In this work, we report that the reflectance-only measurement in normal incidence can also be used to evaluate optical constants when it is combined with two-step analysis methods, i.e., the Kramers-Kronig transformation of R to obtain the phase change upon the reflection and the numerical analysis of the Fresnel equation. By examining the influences of the uncertainty in R or in the phase on the final results, we show that the precise measurement of R over a broad spectral range is essential to guarantee the accuracy of the optical constants determined in this method.
토픽 클러스터링을 이용한 기초연구지원사업의 특성도출 연구
함선영(Sun Young Hamh),염경환(Yeom, Kyeong Hwan),윤수진(Yun, Su Jin) 한국기술혁신학회 2018 한국기술혁신학회 학술대회 발표논문집 Vol.2018 No.11
본 연구에서는 과제요약 정보(연구목표, 내용, 기대효과, 키워드)를 활용하여 기초연구지원사업의 특성을 도출할 수 있는 방안을 모색하였다. 기존에 주로 활용되던 정보(연구개발단계 등) 대비 방대한 양의 과제요약 정보를 활용하기 위해 토픽 클러스터링 모델을 이용하였다. 그 결과로서 사업별 토픽 분포도를 얻었고, 토픽 분포의 균일한 정도가 사업에 따라 뚜렷한 차이를 보이는 것을 확인하였다. 토픽 분포의 균일한 정도에 따른 사업구분과 기존에 주로 사용되던 정보에 따른 사업구분을 비교분석하였고, 이를 기반으로 토픽 클러스터링을 이용한 기초연구지원 사업의 특성 도출 가능성에 대해 논의하였다. We studied the characteristics of the basic research support programs by using topic clustering model with the project information(title, goal, contents, keywords). As a result, we obtained the topic distribution for each programs that shows a clear difference between them according to the programs. We compared the program divisions by the topic distribution with other conditions in aspects of ‘Researcher-driven basic research’. Based on the result, we discussed the reliability on application of the method.
데이터웨어하우스 개발수명주기상에서 데이터 품질의 평가요소 및 품질향상 방안에 관한 연구
이종만,함도훈 경복대학 1999 京福論叢 Vol.3 No.-
본 연구에서는 데이터웨어하우스 구축시 핵심성공요인인 데이터 품질의 확보방안에 대해 살펴보고 있다. 데이터웨어하우스를 간단하게 말한다면 의사결정을 위해 최적화된 데이터베이스라고 정의할 수 있으며 그래서 많은 조직에서 데이터웨어하우스를 도입하려고 노력하고 있다. 또한 데이터 품질은 데이터 사용자가 사용하기에 적합한 데이터라고 정의할 수 있다. 또한 많은 문헌 및 조사에서 데이터웨어하우스 구축시 고품질의 데이터 확보가 핵심성공요인이라고 주장하고 있다. 본 연구에서는 데이터 품질의 요건으로 접근성, 해석가능성, 유용성, 신뢰성의 4가지 영역으로 나눌 수 있으며 각 영역에는 세부항목들이 있다는 것을 지적하고 있다. 실제로 데이터 품질을 향상시키는 유일한 방법은 데이터의 사용을 지속적으로 증가시키는 방법이다. 만일 조직에서 데이터의 품질 향상을 원한다면 각각의 데이터 요소들에 대해 엄격한 규칙을 적용한 사용이 필요하다. 이러한 고품질의 데이터 확보 위해서는 개발자 뿐만아니라 비즈니스 즉,실제 사용자의 관심과 참여가 무엇보다 중요하다. This paper proposes data quality improvement method for the datawarehouse development. A simple definition of a datawarehouse is : a database that is optimized for decision support. Therefore, now many organizations are trying to introduce it. This paper define "data quality" as data that are fit for use by data consumers. In additon, data quality is critical success factor in the quality literature and survey. The results indicate four dimensions of data quality : accessible, interpretable, useful, believable. Each has measurement items. The only way to truly improve data quality is to increase the use of that data. If an organization wants to improve data quality, it needs to ensure that there is stringent use of each data element. Not only Business staff but also Is department members must involve the datawarehouse development and implementation project to improve data quality.
Roh, Chang Jae,Hamh, Sun Young,Woo, Chang-Soo,Kim, Kwang-Eun,Yang, Chan-Ho,Lee, Jong Seok Springer US 2017 Nanoscale research letters Vol.12 No.1
<P>We investigate the ferroelectric state of a tetragonal BiFeO<SUB>3</SUB> thin film grown on a LaAlO<SUB>3</SUB> (001) substrate using an optical second harmonic generation (SHG) microscope. Whereas the ferroelectric state of this material hosts nanometer-sized domains which again form micrometer-sized domains of four different configurations, we could figure out the characteristic features of each domain from the SHG mapping with various sizes of the probe beam, i.e., from 0.7 to 3.9 μm in its diameter. In particular, we demonstrate that a single micrometer-sized domain contributes to the SHG as a coherent summation of the constituent nanometer-sized domains, and multi-micrometer-sized domains contribute to the SHG as an incoherent summation of each micro-domain.</P>
Han, J W,Hamh, S Y,Kim, T H,Lee, K S,Yu, Nan Ei,Ko, Do-Kyeong,Lee, J S Optical Society of America 2014 Optics letters Vol.39 No.19
<P>To extract optical constants of nontransmitted samples in the terahertz (THz) spectral region, we employ a THz emitter-sample hybrid structure where THz pulses are generated at the emitter surface and multiply reflected at the interface between the THz emitter and the sample. Since each THz electric field profile appears well separated in a time domain, we could obtain the amplitude and phase spectra for each pulse from the Fourier transform, and determine the optical constants of the sample numerically based on the Fresnel equations. We applied this technique for doped semiconductors, and found that obtained optical constants are in good agreement with the values determined by using other conventional THz techniques.</P>