헬륨 마이크로파 플라즈마 토치의 개발과 특성에 관한 연구

曺競鉉,朴勇男 한국교원대학교 환경과학연구소 2001 환경연구논문집 Vol.- No.6

MPT는 최근에 개발된 마이크로파 플라즈마로서 수용매에 강하다. 여러 가지의 변형된 형태의 MPT를 개발하여 구조에 따른 플라즈마의 방전되는 형태를 조사한 결과 이중관 토치는 플라즈마 기체를 적게 소모하여 쉽게 플라즈마가 형성되었으나 토치의 끝이 높은 온도에 견디지 못하고 쉽게 상했다. ICP토치와 같은 형태의 삼중관 토치에 석영관을 중심관으로 사용할 때 가장 안정되고 대칭적인 플라즈마를 형성할 수 있었다. 바탕선을 조사해 본 결과 He MPT는 대기 중으로 돌출되어 대기와 많이 혼합되고 질소에 의해 quenching되는 것으로 보여진다. Membrane desolvator를 탈용매화 장치로 사용하여 헬륨 MPT의 감도를 조사해 본 결과 아르곤 MPT와 비교할 때 대부분의 원소에 대헤 검출한계가 10배 이상 높았다. 그러나 여기 에너지가 높은 원소는 비교적 효율적으로 검출할 수 있었다. 헬륨 마이크로파 플라즈마는 적은 양의 플라즈마 기체만 필요하여(약 1.6L/min) 경제적이며 매우 안정된 형태를 보여주었다. 플라즈마의 분광특성을 조사한 결과 들뜸온도 4950 K, 전자 밀도 3.28×10^(14) cm^(-3)로 측정되었다. MPT, which bas been developed recently, is very tolerant to aqueous samples. Several types of MPT have been investigated and is found that the double concentric tube could sustain a stable plasma at a low plasma gas flow rate. However, the tip of torch is easily ruined. Triple concentric torch has shown the best stability and the plasma shape, much like that of ICP, especially when the central channel is quartz. The plasma is exposed and mixed with air as is suggested from the background spectrum, which leads to quenching of He MPT. Sensitivity of helium MPT equipped with a membrane desolvator has shown 10 times lower than that of Argon MPT for most of elements except for the ones with relatively high excitation energy. He MPT requires small plasma flow rate (about 1.6 L/min), stable and simple to use. Excitational temperature and electron number density measured are 4950 K and 3.28 × 10^(14) cm^(-3), respectively.

헬륨 마이크로파 플라즈마 토치의 개발과 특성에 관한 연구

曺競鉉,朴勇男 한국교원대학교 환경과학연구소 2002 환경연구논문집 Vol.- No.7

MPT는 최근에 개발된 마이크로파 플라즈마로서 수용매에 강하다. 여러 가지의 변형된 형태의 MPT를 개발하여 구조에 따른 플라즈마의 방전되는 형태를 조사한 결과 이중관 토치는 플라즈마 기체를 적게 소모하며 쉽게 플라즈마가 형성되었으나 토치의 끝이 높은 온도에 견디지 못하고 쉽게 상했다. ICP토치와 같은 형태의 삼중관 토치에 석영관을 중심관으로 사용할 때 가장 안정되고 대칭적인 플라즈마를 형성할 수 있었다. 바탕선을 조사해 본 결과 He MPT는 대기 중으로 돌출되어 대기와 많이 혼합되고 질소에 의해 quenching되는 것으로 보여진다. Membrane desolvator를 탈용매화 장치로 사용하여 헬륨 MPT의 감도를 조사해 본 결과 아르곤 MPT와 비교할 때 대부분의 원소에 대해 검출한계가 10배 이상 높았다. 그러나 여기 에너지가 높은 원소는 비교적 효율적으로 검출할 수 있었다. 헬륨 마이크로파 플라즈마는 적은 양의 플라즈마 기체만 필요하여(약 1.6L/min)경제적이며 매우 안정된 형태를 보여주었다. 플라즈마의 분광특성을 조사한 결과 들뜸온도 4950K, 전자밀도 3.28×10^14㎝^-3로 측정되었다. MPT, which has been developed recently, is very tolerant to aqueous samples. Several types of MPT have been investigated and is found that the double concentric tube could sustain a stable plasma at a low plasma gas flow rate. However, the tip of torch is easily ruined. Triple concentric torch has shown the best stability and the plasma shape, much like that of ICP, especially when the central channel is quartz. The plasma is exposed and mixed with air is suggested from the background spectrum, which leads to quenching of He MPT. Sensitivity of helium MPT equipped with a membrane desolvator has shown 10 times lower than that of Argon MPT for most of elements except for the ones with relatively high excitation energy. He MPT requires small plasma flow rate(about 1.6L/min), stable and simple to use. Excitational temperature and electron number density measured are 4950 K and 3.28×10^14㎝^-3, respectively.

In situ 고상 에피택시 방법에 의한 CoSi₂/Si(111)구조의 형성

이정주,강민성,김현수,최치규,이운환,이종덕,이영백,김건호,이정용 濟州大學校 基礎科學硏究所 1996 基礎科學硏究 Vol.9 No.2

초고진공에서 공상에피택시(solid-phase epiyaxy, SPE) 방법으로 CoSi₂를 Si(111)기판 위에 에피택시 성장시켰다. 2MeV⁴He++ ion후방산란 분광기와 사중결정 x-선 회절기 및 고분해 투과전자 현미경을 이용하여 성장된 CoSi₂의 상과 조성, 결정성, 그리고 계면의 미시구조를 조사하였다. 초고진공상태의 실온에서 Si(111)-7X7기판에 Co를 약 20 ~50 ?? 중착한 후 SPE에 의하여 실리사이드를 형성시키는 경우 600℃에서는 B-형의 CoSi₂가, 그리고 700℃에서는 A형의 CoSi₂가 선택적으로 에피택시 성장하였으며, 정합성은 B-CoSi₂[110]//Si[110] and CoSi₂(111)//Si(111)이, 그리고 700℃에서는 A-CoSi₂[110]//Si[110], CoSi₂(002)//Si(002)을 나타내었다. Epitaxial films of CoSi₂were grown on Si(111) substrates by in situ solid-phase epitaxy in a ultrahigh vacuum. The phase, the chemical composition, the crystallinity, and the microstructure of the Silicide/Si interface were investigated by 2-MeV⁴He++ ion-backscattering spectrometry, quadruple crystal X-ray diffractometry, and high-resolution transmission eletron micorscopy. High-quality films of either B-type or A-type CoSi₂ could be grown selectively on Si(111) substrates by depositing ~ 20 ~ 50 ?? of Co on a Si(111)-7X7 substrate followed by in situ annealing at 600℃ or 700℃ for 10 min. The matching face relationships are CoSi₂[110]//Si[110] and CoSi₂(111)//Si(111) by B-type CoSi₂ and CoSi₂[110]//Si[110]//Si[110] and CoSi₂(002)//Si(002) for A-type CoSi₂.

Beam line design and beam transport calculation for the μSR facility at RAON

Pak, Kihong,Park, Junesic,Jeong, Jae Young,Kim, Jae Chang,Kim, Kyungmin,Kim, Yong Hyun,Son, Jaebum,Lee, Ju Hahn,Lee, Wonjun,Kim, Yong Kyun Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10

The Rare Isotope Science Project was launched in 2011 in Korea toward constructing the Rare isotope Accelerator complex for ON line experiments (RAON). RAON will house several experimental systems, including the Muon Spin Rotation/Relaxation/Resonance (μSR) facility in High Energy Experimental Building B. This facility will use 600-MeV protons with a maximum current of 660 pμA and beam power of 400 kW. The key μSR features will facilitate projects related to condensed-matter and nuclear physics. Typical experiments require a few million surface muons fully spin-polarized opposite to their momentum for application to small samples. Here, we describe the design of a muon transport beam line for delivering the requisite muon numbers and the electromagnetic-component specifications in the μSR facility. We determine the beam-line configuration via beam-optics calculations and the transmission efficiency via single-particle tracking simulations. The electromagnet properties, including fringe field effects, are applied for each component in the calculations. The designed surface-muon beamline is 17.3 m long, consisting of 2 solenoids, 2 dipoles affording 70° deflection, 9 quadrupoles, and a Wien filter to eliminate contaminant positrons. The average incident-muon flux and spin rotation angle are estimated as 5.2 × 10⁶ μ⁺/s and 45°, respectively.

Antitumor effects of herbal mixture extract in the pancreatic adenocarcinoma cell line PANC1

Pak, Pyo June,Kang, Beob Hwa,Park, Sung Hyo,Sung, Ji Hyun,Joo, Yong Hoon,Jung, Seung Hyun,Chung, Namhyun NATIONAL HELLENIC RESEARCH FOUNDATION 2016 ONCOLOGY REPORTS Vol.36 No.5

<P>A recent study showned that complementary medicine is gradually gaining wide acceptance. In the present study, the herbal mixture extract (H3) composed of 3 oriental herbal plants was investigated for anticancer activity in vitro and in vivo. H3 inhibited PANC1 cell growth by promoting G0/G1 arrest (11% increase) and apoptotic cell death (9% increase). H3 also suppressed stem cell-like side population cells (4% decrease) and migration activity (24% decrease). In contrast, gemcitabine decreased side population cells and migration activity by 3 and 11%, respectively. These effects of H3 and gemcitabine were further studied by examining the expression of apoptosis-associated genes (CXCR4, JAK2 and XIAP) and stem cell-associated genes (ABCG2, POU5F1 and SOX2). We also found that H3 suppressed tumor growth by 46% in a PANC1-xenograft model, while gemcitabine caused a 36% decrease. The antitumor effects of H3 were confirmed by western blot analysis for COX-2 and cytochrome c expression. Furthermore, necrotic cell death and erythrocyte-containing cavities were detected in tumor tissue by hematoxylin and eosin (H&E) staining. Notably, the combinatorial therapy (H3 and gemcitabine) increased tumor growth compared to that in the control. In conclusion, the present study shows that H3 has promise as a therapeutic agent against pancreatic cancer and its cancer stem cells.</P>

Beam Optics Design for the μSR Facility at the RAON Facility in Korea

Pak Kihong,Park Junesic,Kim Yong Hyun,Lee Hyeonjun,Kim Yong Kyun,Lee Ju Hahn 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.5

The beam optics was evaluated to determine the specifications for the electromagnets in the proton beamline and the surface muon beamline at the RAON facility. Beam optics was evaluated, up to the fifth order by using GICOSY software; fringe field effects were also investigated. The distributions of the position and the angular divergence of 600-MeV protons were assumed to be Gaussian, and the initial beam emittance was 0.125 π mm mrad. The proton beamline was optimized by adjusting the positions and the magnetic fields of the electromagnetic components. The full width at half maximum (FWHM) proton beam size at the muon production target was 2.75 mm (x) × 6.73 mm (y), which met the requirement for achieving the maximum surface-muon production at the target. The designed surface-muon beamline is 23-m long and consists of two solenoids, two dipoles with a deflection angle of 70°, six quadrupoles, and a Wien filter. For an initial muon beam size of 6 cm (x) × 2 cm (y), the expected muon intensity at the end of the beamline, where the muon irradiation sample will be located, was estimated to be 7.7 × 107 per second.

Ultrasonic treatment of waste livestock blood for enhancement of solubilization

Yong Woo Jeon,Hyeon Jeong Kim,Myung Seop Shin,Seo Hyun Pak 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.1

The aim of this study was to recycle the waste livestock blood as one of the waste biomass by turning proteins, the main constituent of blood, into effective biological resources like amino acid. Ultrasonic technology was applied to solubilize the proteins in the waste livestock blood. And of the multiple ultrasonic frequencies tested, 20 kHz was confirmed to yield the highest solubilization rate. The optimum pretreatment conditions were determined to be 30-min treatment at an ultrasonic irradiation density of 0.5 W/mL, which resulted in a solubilization rate of 96.01%. Also, a gel permeation chromatography (GPC) confirmed that a large amount of proteins were solubilized, and in an experiment where ultrasonic treatment was applied to kill bacteria, death rates of general bacteria and total coliforms were found to be reduced by 99.93% and 100%, respectively. Based on these results, ultrasonic technology was confirmed to be a crucial part of treating and recycling the proteins in waste livestock blood.

New Garden Mum Cultivar, ‘Purple Ball’ with Decorative Type of Purple Petals

Taeg-Yong Choi,Ha-Seung Pak,Seong-Deog Lee,Euy-Seog Yang,Hyun-Seog Kim 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Development of mathematical model on regionalization using records of livestock related vehicles for control strategy of highly pathogenic avian influenza

Jong hyun Seo,Hyuk Park,Kwang Hee Han,Woo seog Jeong,Ha chung Yoon,Ki Hyun Cho,Chung Sik Jung,Yong Myung Kang,Hong Sik Park,Son Il Pak,Hun seok Kang 한국예방수의학회 2017 예방수의학회지 Vol.41 No.4

In this paper, a mathematical model of regionalization based on graph theory to investigate the patterns induced by movements of livestock vehicles in cities under outbreaks of highly pathogenic avian influenza (HPAI) is proposed. We then compare the results of simulation from the regionalization model to actual HPAI outbreaks in 2016/2017 to evaluate the validity of the model. Specifically, we (1) configured a complex network structure with analytic tools and properties in graph theory to abstract the paths among farms and livestock facilities; (2) employed statistical methods to estimate the possibility of propagation between two clusters; (3) applied the developed method to an actual HPAI outbreak in Korea in 2016 and conducted a simulation to determine if the proposed modeling for regionalization is an effective prediction measure. The clustered regions proposed by the simulation correctly reflected the regional clustering of actual cases, while simultaneously contain the cities exposed to potential damage when separated. Based on these findings, we conclude that our proposed regionalization model is suitable for making policy judgments to establish a preemptive biosecurity system.

해외기업에 인수된 한국인 종업원들의 직무만족에 관한 연구

박용석(Yong Suhk Pak),류기현(Ki Hyun Ryu) 한국경영학회 2008 經營學硏究 Vol.37 No.3

Since the financial crisis of 1997, international acquisitions by foreign firms for the purpose of restructuring financially distressed Korean firms have grown steadily. Despite this trend, empirical studies on cross-border M&As in Korea are insufficient compared to those in the U.S., Europe, or Japan. One of the significant factors affecting successful integration after acquisitions is an effective human resource management (HRM). Believing that integration after acquisitions influences firm performance through employee`s cooperative behaviors, post merger integration (PMI) research focusing on employees seems meaningful. If employees do not have the cooperative will and intention to accomplish assignments, the integration synergies cannot be expected even if the employees have the ability and competence to do the work. This implies that a negative change in employees` job satisfaction during the PMI needs to be properly and carefully managed for the positive results after the acquisition. Previous research on HRM related to international acquisitions overlooked the psychological factors that employees may experience. In addition, a comparative analysis between the phenomenal and psychological factors after international acquisitions affecting Korean employees` job satisfaction has not been examined before. We need to understand how different factors such as cultural difference and restructuring efforts affect employees` job satisfaction after the international acquisition. Accordingly, we categorized the change of organizational culture and identity as the psychological factors, and the change of organizational replacement and restructuring as the phenomenal factors that may affect job satisfaction. We compared the influence of these factors on employees` job satisfaction. 513 survey questionnaires were responded by employees who were working for 15 different firms that had been internationally acquired. An interesting result that was not shown in the previous research was found. A change in identity and culture after the international acquisition was shown to be a more important factor that affected employees` job satisfaction than the phenomenal factors such as restructuring or job rotation. The result might reflect only the Korean-specific context but mandates a careful management of psychological factors of Korean employees after cross-border acquisitions. Managerial issues are discussed and further research focusing on employee`s psychological changes is recommended at the end.