Binder-Free Cu–In Alloy Nanoparticles Precursor and Their Phase Transformation to Chalcogenides for Solar Cell Applications

Lim, Ye Seul,Jeong, Jeunghyun,Kim, Jin Young,Ko, Min Jae,Kim, Honggon,Kim, BongSoo,Jeong, Unyong,Lee, Doh-Kwon American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.23

<P>A low-cost, nonvacuum fabrication route for CuInSe<SUB>2</SUB> and CuInS<SUB>2</SUB> thin films is presented. To produce these films, binder-free colloidal precursors were prepared using Cu–In intermetallic nanoparticles that were synthesized via a chemical reduction method. The Cu–In alloy precursor films were transformed to CuInSe<SUB>2</SUB> and CuInS<SUB>2</SUB> by reactive annealing in chalcogen-containing atmospheres at atmospheric pressure. The as-synthesized nanoparticles and the annealed films were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, electron probe X-ray microanalysis, Raman spectroscopy, and Auger electron spectroscopy depth profile measurements to elucidate the phase evolution pathway and the densification mechanism of the Cu–In–Se–S system. Solar cell devices made with CuInSe<SUB>2</SUB> and CuInS<SUB>2</SUB> absorbing layers exhibited power conversion efficiencies of 3.92% and 2.28%, respectively. A comparison of the devices suggested that the microstructure of the absorbing layer had a greater influence on the overall photovoltaic performance than the band gap energy. A diode analysis on the solar cell devices revealed that the high saturation current density and diode ideality factor caused lower open-circuit voltages than would be expected from the band gap energies. However, the diode analysis combined with the microstructural and compositional analysis offered guidance about how to improve the photovoltaic performance of these devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-23/jp401637b/production/images/medium/jp-2013-01637b_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp401637b'>ACS Electronic Supporting Info</A></P>

Cerebral lateralization index based on intensity of bold signal of FMRI.

Lim, Dae-Woon,Min, Byung-Chan,Kim, Hyun-Jun,Choi, Mi-Hyun,Lee, Soo-Jeong,Jun, Jae-Hoon,Lee, Bongsoo,Chung, Soon-Cheol Gordon and Breach 2008 INTERNATIONAL JOURNAL OF NEUROSCIENCE - Vol.118 No.11

<P>This study proposes a new cerebral lateralization index (LI) on the basis of neural activation intensity. Eight right-handed male college students (mean age 23.5 years) and 10 right-handed male college students (the mean age 25.1 years) participated in this study of visuospatial and verbal tasks, respectively. Functional brain images were taken from 3T MRI using the single-shot EPI method. A cerebral LI based on neural activation area (i.e., number of activated voxels) and another based on neural activation intensity (i.e., intensity of BOLD (blood oxygen level dependent)) were calculated for both cognition tasks. The result of calculating a cerebral LI based on neural activation area suggested that the right hemisphere is dominant during visuospatial tasks and the left hemisphere is dominant during verbal tasks. When a cerebral LI was computed on the basis of the neural activation intensity, it was shown that the area of cerebral lateralization closely related to visuospatial tasks is the superior parietal lobe, and the area of cerebral lateralization closely related to verbal tasks is the inferior and middle frontal lobe. Since the proposed method can determine the dominance of the cerebrum by each area, it can be helpful to determine cerebral lateralization accurately and easily.</P>

Development of a Magnetic Resonance-Compatible Galvanic Skin Response Measurement System Using Optic Signal.

Lim, Dae-Woon,Park, Jong-Rak,Choi, Mi-Hyun,Lee, Soo-Jeong,Choi, Jin-Seung,Kim, Hyung-Sik,Yi, Jeong-Han,Tack, Gye-Rae,Lee, Bongsoo,Chung, Soon-Cheol Gordon and Breach 2009 International journal of neuroscience Vol.119 No.9

<P>The purpose of the current study is to develop a magnetic resonance (MR)-compatible galvanic skin response (GSR) measurement system that can measure the GSR signal during MR image acquisition. If GSR signals are measured simultaneously with the acquisition of MR images, there can be a mutual interference effect. The present system was designed to block noises caused by the main magnetic field, the gradient magnetic field, and the radio frequency (RF) pulse when MR images are acquired. To minimize the distortion of MR images, the GSR measurement system was shielded. Especially, this system used analog, not digital, elements in order to remove any possible effects on MR images. An RF-interference-free optical data link using the pulse-width modulation technique was adopted in order to transmit GSR signals measured inside the MR room. The experiment verified that a reliable GSR signal can be obtained without deteriorating the MR image. It is expected that this system can be used for diverse medical and neuroscience studies.</P>

Feasibility Study on Gamma Energy Spectroscopy of Bismuth Nanoparticlesloaded Plastic Scintillator for Portal Monitoring Using Monte Carlo Simulations

Taeseob Lim,Siwon Song,Jae Hyung Park,Jinhong Kim,Seunghyeon Kim,Hyungi Byun,Seokhyeon Jegal,Bongsoo Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Plastic scintillators can be used to find radioactive sources for portal monitoring due to their advantages such as faster decay time, non-hygroscopicity, relatively low manufacturing cost, robustness, and easy processing. However, plastic scintillators have too low density and effective atomic number, and they are not appropriate to be used to identify radionuclides directly. In this study, we devise the radiation sensor using a plastic scintillator with holes filled with bismuth nanoparticles to make up for the limitations of plastic materials. We use MCNP (Monte Carlo N-particle) simulating program to confirm the performance of bismuth nanoparticles in the plastic scintillators. The photoelectric peak is found in the bismuth-loaded plastic scintillator by subtracting the energy spectrum from that of the standard plastic scintillator. The height and diameter of the simulated plastic scintillator are 3 and 5 cm, respectively, and it has 19 holes whose depth and diameter are 2.5 and 0.2 cm, respectively. As a gamma-ray source, Cs-137 which emits 662 keV energy is used. The clear energy peak is observed in the subtracted spectrum, the full width at half maximum (FWHM) and the energy resolution are calculated to evaluate the performance of the proposed radiation sensor. The FWHM of the peak and the energy resolution are 61.18 keV and 9.242% at 662 keV, respectively.

MCNP Simulation of Gamma Energy Spectra Using Plastic Scintillator with Bismuth

Taeseob Lim,Siwon Song,Seunghyeon Kim,Jaehyung Park,Jinhong Kim,Jin-Ho Kim,Bongsoo Lee 대한방사선방어학회 2021 대한방사선방어학회 학술발표회 논문요약집 Vol.2021 No.11

Simulation of Bismuth-Loaded Plastic Scintillators for Gamma-ray Spectroscopy

Taeseob Lim,Siwon Song,Seung Hyeon,Jae Hyung Park,Jinhong Kim,Sang-Hun Shin,Bongsoo Lee 대한방사선방어학회 2022 대한방사선방어학회 학술발표회 논문요약집 Vol.2022 No.04

Identification of Gamma Radionuclides Using Organic Scintillator with Bismuth Film

Taeseob Lim,Siwon Song,Seung Hyeon Kim,Jaehyung Park,Jinhong Kim,Jin-Ho Kim,Bongsoo Lee 대한방사선방어학회 2021 대한방사선방어학회 학술발표회 논문요약집 Vol.2021 No.04

영국 The Duke of Edinburgh’s Award 프로그램 고찰을 통한 국민체력100 정책제안

강봉수(Kang, Bongsoo),임승엽(Lim, Seungyup) 한국스포츠사회학회 2021 한국스포츠사회학회지 Vol.34 No.3

본 연구의 목적은 국민체력100 정책사업의 한계점을 발견하고 영국 The Duke of Edinburgh’s Award 프로그램을 벤치마킹하여 국민체력100 사업에 필요한 정책 제안을 하는 데 있다. 이를 위하여 본 연구에서는 선행연구에 대한 체계적 문헌고찰법을 진행하여 다음과 같은 연구결과를 도출하였다. 국민체력100 사업의 한계점으로 1) 예산 부족으로 인한 인증센터와 체력증진교실 운영의 한계, 2) 맞춤형 프로그램 수업의 저조한 참여율, 3) 시설부족, 4) 스포츠활동 인증 서비스의 한계, 5) 운동프로그램의 차별성 부재를 발견하였다. 이에 The Duke of Edinburgh’s Award 프로그램을 통한 정책 제안으로 예산부족을 위해 1) 정부와의 논의를 통한 예산 증액, 2) 홈페이지를 이용한 후원 모집, 3) 파트너쉽을 통한 지원금 확보, 4) 등록금 청구 등을 제안하였고, 운동처방 맞춤형 프로그램 참여율 제고를 위해 1) 학교, 지역 기관, 스포츠클럽 등의 다양한 장소에서 진행, 2) 온라인 기록노트의 활용, 3) 진행 리더의 역할 강화를 제시하였다. 마지막으로 시설부족에 대한 정책 제안으로 1) 공공스포츠클럽 시설 활용, 2) 초 · 중 · 고등학교 시설 활용, 3) 전국 체육시설의 활용 등을 제안하였다. The purpose of this study was to identify the limitations of the National Fitness 100 project and to propose alternative policies by reviewing the UK’s The Duke of Edinburgh’s Award program. To collect data, this study conducted a literature review on proceeded research. As result, we found that the limitations of the National Fitness 100 project are: 1) limits of operation of fitness certification center and fitness promotion classroom due to lack of budget, 2) low participation rate in customized exercise prescription programs, 3) lack of facilities, 4) limitations of sports activity certification service, and 5) lack of differentiation in the exercise program. Policy proposals for the lack of budget through The Duke of Edinburgh’s Award program include 1) the budget increase through negotiation with the government, 2) recruiting sponsorships through the website, 3) securing support through partnership, and 4) charging registration and examination fees. To increase the participation rate in the customized exercise prescription program, the policy proposals include 1) conducting the program in various places such as schools, local institutions, and sports clubs, 2) the use of online record notes, and 3) strengthening the role of the progressive leader. Lastly, the policy proposals for the lack of facilities are 1) use of public sports facilities, 2) use of elementary, middle, and high school facilities, and 3) use of national sports facilities.

Enhancing lipid productivity of Chlorella vulgaris using oxidative stress by TiO2 nanoparticles

Nam Kyu Kang,양지원,Bongsoo Lee,Gang-Guk Choi,Myounghoon Moon,Min S. Park,JitKang Lim 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.5

Ability to increase the lipid production in microalgae is one of the heavily sought-after ideas to improvethe economic feasibility of microalgae-derived transportation fuels for commercial applications. We used the oxidativestress by TiO2 nanoparticles, a well-known photocatalyst, to induce lipid production in microalgae. Chlorella vulgarisUTEX 265 was cultivated under various concentrations of TiO2 ranging from 0.1 to 5 g/L under UV-A illumination. Maximum specific growth rate was affected in responding to TiO2 concentrations. In the presence of UV-A, chlorophyllconcentration was decreased at the highest concentration of TiO2 (5 g/L TiO2) by oxidative stress. The fatty acid methylester (FAME) composition analysis suggested that oxidative stress causes the accumulation and decomposition of lipids. The highest FAME productivity was 18.2 g/L/d under low concentrations of TiO2 (0.1 g/L) and a short induction time(two days). The controlled condition of TiO2/UV-A inducing oxidative stress (0.1 g/L TiO2 and two days induction)could be used to increase the lipid productivity of C. vulgaris UTEX 265. Our results show the possibility of modulatingthe lipid induction process through oxidative stress with TiO2/UV-A.

Liquid Light Guide Based Radiation Sensor System for Remote Gamma-ray Spectroscopy

Jae Hyung Park,Seunghyeon Kim,Taeseob Lim,Siwon Song,Jinhong Kim,Sang Hun Shin,Bongsoo Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Gamma-ray spectroscopy, which is an appropriate method to identify and quantify radionuclides, is widely utilized in radiological leakage monitoring of nuclear facilities, assay of radioactive wastes, and decontamination evaluation of post-processing such as decommissioning and remediation. For example, in the post-processing, it is conducted to verify the radioactivity level of the site before and after the work and decide to recycle or dispose the generated waste. For an accurate evaluation of gamma-ray emitting radionuclides, the measurement should be carried out near the region of interest on site, or a sample analysis should be performed in the laboratory. However, the region is inaccessible due to the safety-critical nature of nuclear facilities, and excessive radiation exposure to workers could be caused. In addition, in the case of subjects that may be contaminated inside such as pipe structures generated during decommissioning, surveying is usually done over the outside of them only, so the effectiveness of the result is limited. Thus, there is a need to develop a radiation measurement system that can be available in narrow space and can sense remotely with excellent performance. A liquid light guide (LLG), unlike typical optical fiber, is a light guide which has a liquid core. It has superior light transmissivity than any optical fiber and can be manufactured with a larger diameter. Additionally, it can deliver light with much greater intensity with very low attenuation along the length because there is no packing fraction and it has very high radiation resistant characteristics. Especially, thanks to the good transmissivity in UV-VIS wavelength, the LLG can well transmit the scintillation light signals from scintillators that have relatively short emission wavelengths, such as LaBr3:Ce and CeBr3. In this study, we developed a radiation sensor system based on a LLG for remote gamma-ray spectroscopy. We fabricated a radiation sensor with LaBr3:Ce scintillator and LLG, and acquired energy spectra of Cs-137 and Co-60 remotely. Furthermore, the results of gamma-ray spectroscopy using different lengths of LLG were compared with those obtained without LLG. Energy resolutions were estimated as 7.67%, 4.90%, and 4.81% at 662, 1,173, and 1,332 keV, respectively for 1 m long LLG, which shows similar values of a general NaI(Tl) scintillator. With 3 m long LLG, the energy resolutions were 7.92%, 5.48%, and 5.07% for 662, 1,173, and 1,332 keV gamma-rays, respectively.