Color Change in Mixed Zinc Sulfide Composite Displays due to a Biased AC Electric Field

Kim Taehun,Kim Ha Sul 한국물리학회 2023 새물리 Vol.73 No.8

In this study, we developed two types of electroluminescent (EL) devices. One type was made solely of ZnS:(Cu, Al, Mn) composite and the other type was a mixture of the ZnS:(Cu, Al, Mn) and ZnS:(Cu, Cl) composites. The light-emitting device was fabricated by mixing ZnS phosphor and polydimethylsiloxane between two indium tin oxide glasses. When the ZnS:(Cu, Cl) composites were added to the ZnS:(Cu, Al, Mn) composites, the intermixed EL device emitted brighter light than the device fabricated with only the ZnS:(Cu, Al, Mn) composite at the same bias and frequency. The International Commission on Illumination color coordinates of the EL devices produced with only the ZnS:(Cu, Al, Mn) composites and with the intermixed ZnS:(Cu, Al, Mn) phosphors and ZnS:(Cu, Cl) composites were (0.30, 0.40) and (0.24, 0.42), respectively, at 100 Hz. These values changed to (0.28, 0.31) and (0.23, 0.32), respectively, at 500 Hz. We believe that the ZnS EL device composed of the two mixed composites could be utilized as an illumination light source for large-area displays, which, in turn, require active color expression.

보문 : 큰느타리버섯 갓우수 품종 육종

임착한 ( Chak Han Im ),김민근 ( Min Keun Kim ),제희정 ( Hee Jung Je ),김경희 ( Kyung Hee Kim ),김선영 ( Sun Young Kim ),김계자 ( Kye Ja Kim ),박성자 ( Sung Ja Park ),하영아 ( Young A Ha ),김미진 ( Mi Jin Kim ),김설화 ( Sul Ha Kim 한국균학회 2012 韓國菌學會誌 Vol.40 No.3

갓모양이 우수한 계통과 대길이가 길고 속성형질을 가진 계통을 모본으로부터 교배육종으로 두 가지 형질을 모두 가진 우수품종을 육성하고자 하였다. 낮은 갓명도 형질의 동형접합체를 만들기 위하여 KNR2312 유래 단핵균사들로 자가교배를 실시하여 갓명도가 45.2, 품질이 6.5인 중간모본 KNR2312-2636-10 × 18을 선발하였고, 이를 A8B10(나) 유래 단핵균사와 이종교배 하였다. 이후 낮은 품질을 개선하기 위하여 KNR2312 유래 단핵균사와 여교배를 실시하여 갓명도가 49.5, 품질이 7.3 수확량이 95.1 g인 가5나5KNR2312-47KNR2312-12 × 38 계통을 선발하였다. 선발된 계통은 갓모양이 우수하고 특히 갓끝이 24mm로 다듬기나 유통중 파손이 적을 것으로 사료된다. Two strains Pleurotus eryngii KNR2312 and A8B10 (Na) which have good traits in cap quality and speedy growing were selected to breed a new strain carrying the two traits. KNR2312-2636-10 × 18 (Ga) with 45.2 cap lightness and 6.5 quality was breeded by a consecutive inbreeding between KNR2312-derived monokaryons. Ga5 × Na5 came from outcrossing between Ga and Na was backcrossed with KNR2312-derived monokaryons twice to improve quality in cap color and shape. Therethrough Ga5NaKNR2312-47KNR2312-12 × 38 carrying lightness of 49.5, quality of 7.3 and weight of 95.1 g was selected. The selected strain possesses good quality and dark color of cap. Especially its edge is 24 mm thick, therefore it is not likely damaged during processing and distribution.

Dark current improvement of the type-II InAs / GaSb superlattice photodetectors by using a gate bias control

Kim, Ha Sul,Myers, S.,Klein, B.,Kazemi, A.,Krishna, S.,Kim, Jun Oh,Lee, Sang Jun 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.

Ventilation impairment of residents around a cement plant

Sul Ha Kim,Chul Gab Lee,Han Soo Song,Hyun Seung Lee,Min Soo Jung,Jae Yoon Kim,Choong Hee Park,Seung Chul Ahn,Seung Do Yu 대한직업환경의학회 2015 대한직업환경의학회지 Vol.27 No.-

Objectives: To identify adverse health effects due to air pollution derived from a cement plant in Korea. The ventilation impairment in residents around a cement plant was compared to another group through a pulmonary function test (PFT). Methods: From June to August of 2013, both a pre and post-bronchodilator PFT was conducted on a “more exposed group (MEG)” which consisted of 318 people who lived within a 1 km radius of a cement plant and a “less exposed group (LEG)” which consisted of 129 people who lived more than 5 km away from the same plant. The largest forced expiratory volume in a one second (FEV1) reading and a functional residual capacity (FVC) reading were recorded after examining the data from all of the usable curves that were agreed upon as valid by PFT experts of committee of National Institute of Environmental Research. The global initiative for chronic obstructive lung disease (GOLD) criteria for COPD, defined the FEV1/FVC ratio < 0.7 as the obstructive type, and the FEV1/FVC ratio ? 0.7 and FVC% predicted < 80% were as the restrictive type. The FVC% predicted value was estimated using Korean equation. We compared the proportion of lung function impairments between the MEG and the LEG by using a chi-square, and estimated the OR of obstructive and restrictive ventilation impairments by logistic regression. Results: The obstructive type impairment proportion was 9.7% in the MEG, whereas it was 8.5% in the LEG. The restrictive type was 21.6% in the MEG which was more than the 12.4% of the LEG. The odds ratio (OR) of total ventilation impairment in the MEG was 2.63 (95% CI 1.50 ~ 4.61) compared to the LEG. The OR of obstructive type in the MEG was 1.60 (95% CI 0.70 ~ 3.65), the smoking history was 3.10 (CI 1.10 ~ 8.66) whereas OR of restrictive type in the MEG was 2.55 (95% CI 1.37 ~ 4.76), the smoking history was 0.75 (95% CI 0.35 ~ 1.60) after adjusting for sex and age. Level of exposure to particulate played a role in both types. However, it appeared to be a significant variable in restrictive type, while smoking history was also an important variable in obstructive type. Conclusion: Although this study is a limited cross-section study with a small number of subjects, ventilation impairment rate is higher in the MEG. There might be a possibility that it is due to long-term exposure to particulate dust generated by the cement plant.

Passivation Study of InAs/GaSb Type-II Strained Layer Superlattice in Mid-wave Infrared Photodetector

Kim Ha Sul 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.9

This paper reports the results of a passivation study of InAs/GaSb type-II strained layer superlattice for a mid-wave infrared detector with p-on-n polarity. The cutoff wavelength of the fabricated photodiode was observed to be 5.5 μm at 77 K. At a negative bias of 0.1 V, the dark current density was measured to be 2.8 × 10-5, 8.2 × 10-5, and 3.1 × 10-2 A/cm2 for the diodes passivated with SiO2 and Si3N4 and the unpassivated diode, respectively. The photodiode passivated with SiO2 demonstrated a reduction in dark current density of approximately three times than that of the diode passivated with Si3N4. Therefore, the dynamic resistance-area product of the photodiode under the negative bias, passivated with SiO2, showed a larger value than that of the device passivated with Si3N4. In contrast, at 100-150 K, the resistance-area product at the zero-bias voltage of the photodiode passivated with Si3N4 showed a higher value than that of the device passivated with SiO2. It is believed that the relatively low thermal stress between GaSb and Si3N4 reduced the dark current density at zero bias and increased R0A in this temperature range.

InAs/GaSb 제2형 응력 초격자 nBn 장적외선 검출소자 설계, 제작 및 특성평가

Kim, Ha Sul,Lee, Hun,Klein, Brianna,Gautam, Nutan,Plis, Elena A.,Myers, Stephen,Krishna, Sanjay 한국진공학회 2013 Applied Science and Convergence Technology Vol.22 No.6

InAs/GaSb 제2형 응력 초격자(strained layer type II superlattice, T2SL)을 이용한 nBn 구조 장적외선 검출소자의 설계 및 제작을 하였다. InAs와 GaSb 두께에 따른 T2SL 구조의 장적외선 밴드갭 에너지를 Kronig-Penney 모델을 이용하여 계산하였다. 소자의 암전류 밀도를 줄이기 위해서, nBn 구조에서 장벽층인 $Al_{0.2}Ga_{0.8}Sb$ 성장 중에 Te 보상도핑(compansated doping)을 하였다. 온도(T) 80 K 및 인가전압($V_b$) -1.5 V에서, 반응스펙트럼 측정을 통한 소자의 차단파장은 ${\sim}10.2{\mu}m$ (~0.122 eV)로 나타났다. 또한 온도 변화에 따른 암전류 측정으로부터 도출된 활성화 에너지는 0.128 eV로 계산 되었다. T=80 K 및 $V_b$=-1.5 V에서 암전류는 $1.0{\times}10^{-2}A/cm^2$으로 측정되었다. 흑체복사 적외선 광원을 이용한 반응도(Responsivity)는 소자 온도 80 K 및 인가전압 -1.5 V의 조건에서 0.58 A/W로 측정되었다. Long-wave infrared detectors using the type-II InAs/GaSb strained superlattice (T2SL) material system with the nBn structure were designed and fabricated. The band gap energy of the T2SL material was calculated as a function of the thickness of the InAs and GaSb layers by the Kronig-Penney model. Growth of the barrier material ($Al_{0.2}Ga_{0.8}Sb$) incorporated Te doping to reduce the dark current. The full width at half maximum (FWHM) of the $1^{st}$ satellite superlattice peak from the X-ray diffraction was around 45 arcsec. The cutoff wavelength of the fabricated device was ${\sim}10.2{\mu}m$ (0.12 eV) at 80 K while under an applied bias of -1.4 V. The measured activation energy of the device was ~0.128 eV. The dark current density was shown to be $1.0{\times}10^{-2}A/cm^2$ at 80 K and with a bias -1.5 V. The responsivity was 0.58 A/W at $7.5{\mu}m$ at 80 K and with a bias of -1.5 V.

Optical and Electrical Characteristics of InAs/GaSb Superlattice with Interband Cascade Structure

Ha Sul Kim,Seunghyun Lee,Jun Oh Kim,Sangjun Lee,S. Krishna 한국진공학회 2019 한국진공학회 학술발표회초록집 Vol.2019 No.2

Distribution of the Mesozooplankton Community in the Western Ross Sea Region Marine Protected Area During Late Summer Bloom

Kim, Sung Hoon,Kim, Bo Kyung,Lee, Boyeon,Son, Wuju,Ha, Sun-Yong,Kim, Jeong-Hoon,La, Hyoung Sul 극지연구소 2023 극지연구소 초록집 Vol.- No.-

Cerebellar Shank2 Regulates Excitatory Synapse Density, Motor Coordination, and Specific Repetitive and Anxiety-Like Behaviors

Ha, Seungmin,Lee, Dongwon,Cho, Yi Sul,Chung, Changuk,Yoo, Ye-Eun,Kim, Jihye,Lee, Jiseok,Kim, Woohyun,Kim, Hyosang,Bae, Yong Chul,Tanaka-Yamamoto, Keiko,Kim, Eunjoon Society for Neuroscience 2016 The Journal of neuroscience Vol.36 No.48

<P>Shank2 is a multidomain scaffolding protein implicated in the structural and functional coordination of multiprotein complexes at excitatory postsynaptic sites as well as in psychiatric disorders, including autism spectrum disorders. While Shank2 is strongly expressed in the cerebellum, whether Shank2 regulates cerebellar excitatory synapses, or contributes to the behavioral abnormalities observed in Shank2(-/-) mice, remains unexplored. Here we show that Shank2(-/-) mice show reduced excitatory synapse density in cerebellar Purkinje cells in association with reduced levels of excitatory postsynaptic proteins, including GluD2 and PSD-93, and impaired motor coordination in the Erasmus test. Shank2 deletion restricted to Purkinje cells (Pcp2-Cre; Shank2(fl/fl) mice) leads to similar reductions in excitatory synapse density, synaptic protein levels, and motor coordination. Pcp2-Cre; Shank2(fl/fl) mice do not recapitulate autistic-like behaviors observed in Shank2(-/-) mice, such as social interaction deficits, altered ultrasonic vocalizations, repetitive behaviors, and hyperactivity. However, Pcp2-Cre; Shank2(fl/fl) mice display enhanced repetitive behavior in the hole-board test and anxiety-like behavior in the light-dark test, which are not observed in Shan2(-/-) mice. These results implicate Shank2 in the regulation of cerebellar excitatory synapse density, motor coordination, and specific repetitive and anxiety-like behaviors.</P>

Dark current analysis of an InAs/GaSb type II superlattice infrared photodiode with SiO2 passivation

Kim Ha Sul 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.11

In this study, we present the current–voltage (I–V) characteristics of a 10 ML InAs/10 ML GaSb type-II superlattice (T2SL) with p-i-n structures for mid-infrared detection. At a negative bias and a temperature of 50 mV and 77 K, respectively, the cut-off wavelength of the fabricated T2SL photodiode with SiO2 passivation on the mesa side wall was approximately 5.6 μm, and the dark current density was found to be 1.9 × 10–5 A/cm2. The bulk dark current model was adopted in this study to obtain the measured values by modeling, assuming the generation-recombination lifetime of the carrier to be approximately 60 ns, and considering the surface leakage current, as well as the four dark current mechanisms. At low operating temperatures, we inferred that the T2SL photodiode was limited by the effects of surface leakage, whereas the effects of the band-to-band and diffusion components of the dark current were negligible. Therefore, reducing the surface leakage current to obtain high-performance detectors requires the development of advanced passivation materials and technology.