• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2773-2775
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• 1999

포항가속기의 선형가속기 buncher 및 prebuncher 시스템은 가속기 건설 시에 중국의 IHEP로부터 도입된 것이다. 전체적인 시스템은 완성되었으나, 그 동안 몇 가지의 문제점이 있어, 제한된 조건하에서 사용해왔다. 이와 같은 문제점을 해결하여 선형가속기 기계장치를 이용한 연구를 활성화하고 보다 나은 전자빔을 공급해주기 위하여 일부 기계장치를 포함한 모터 및 구동부, 제어부등에 대한 성능개선을 하였고 현장 시험과 설치를 완료하였다. 특히 모터는 설치가 간단하고 정밀한 제어를 할 수 있는 5선 식 5상 스텝 모터를 사용하였고, 구동부는 MOSFET을 이용한 정 전류 초핑 방식을 채택하여 크기와 발열량을 줄였다. 그리고, 제어부는 4축의 독립된 유닛이 단일의 RS485 직렬 접속에 의해서 원격으로 제어가 가능하도록 구성하였다.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1283-1285
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• 2000

고 주파수 스위칭 동작을 하는 DC/DC 컨버터 혹은 인버터를 효율적으로 제작하기 위하여 고주파용 펄스 변압기의 역할은 매우 중요하다. 동작주파수가 수십 혹은 수백 kHz일 경우에는 최소의 부피로 충분한 전력을 수용하면서 변압기를 설계 및 제작하기 위하여 코어 및 권선의 선정, 코어 및 권선의 손실, 변압기의 온도상승요소, 변압기의 발열, 변압기의 누설 인덕턴스, 권선 케페시턴스, 분포 케페시턴스 그리고 공진주파수 등을 고려하여 설계하고 시험 평가하여야 한다. 본 논문에서는 위의 여러가지 요소들을 고려하여 동작주파수가 100kHz인 DC/DC 컨버터 혹은 인버터를 고밀도 제작하기 위하여 고주파용 펄스변압기를 최소의 부피로 수kW 용량으로 변압기의 온도상승요소를 고려하여 설계, 제작 그리고 실험한 결과에 대하여 기술 하고자 한다.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.2
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• pp.112-121
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• 2016

This paper focuses on competencies of data scientists and behavioral intention that affect big data analysis performance. This experiment examined nine core factors required by data scientists. In order to investigate this, we conducted a survey to gather data from 103 data scientists who participated in big data competition at Kaggle platform and used factor analysis and PLS-SEM for the analysis methods. The results show that some key competency factors have influential effect on the big data analysis performance. This study is to provide a new theoretical basis needed for relevant research by analyzing the structural relationship between the individual competencies and performance, and practically to identify the priorities of the core competencies that data scientists must have.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.307-308
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• 2019

The Pohang Light Source (PLS) - II is a 3 GeV third-generation synchrotron radiation facility. To inject electron beam from LINAC, a kicker modulator system and kicker magnets are installed in the PLS-II storage ring tunnel. The injected beam then falls into the storage ring beam dynamic aperture. This paper describes the design and implementation of the solid-state kicker modulator for PLS-II. The solid-state kicker modulator is consisted of high voltage solid state switch stacks. the technical considerations of the solid-state switch stacking for kicker modulator is discussed. The achieved capability of the solid-state kicker modulator demonstrates that is fulfills the design requirement of providing half-sine pulsed current of 10kA (peak), 6us (Base-width), with jitter < 2ns (Standard deviation). simulation and experimental results are presented to demonstrate the performance of the solid-state kicker modulator.

• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.438-445
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• 2008

The purpose of this study was to develop a measurement model based on PLS (Partial least square) method for blood pressures. Measurement system for blood pressure signals consisted of pressure sensor, va interface and embedded module. A mercury sphygmomanometer was connected with the measurement system through 3-way stopcock and used as reference of blood pressures. The blood pressure signals of 20 subjects were measured and tests were repeated 5 times per each subject. Total of 100 data were divided into a calibration set and a prediction set. The PLS models were developed to determine the systolic and the diastolic blood pressures. The PLS models were evaluated by the standard methods of the British Hypertension Society (BHS) protocol and the American Association for the Advancement of Medical Instrumentation (AAMI). The results of the PLS models were compared with those of MAA (maximum amplitude algorithm). The measured blood pressures with PLS method were highly correlated to those with a mercury sphygmomanometer in the systolic ($R^2=0.85$) and the diastolic blood pressure ($R^2=0.84$). The results showed that the PLS models were the effective tools for blood pressure measurements with high accuracy, and satisfied the standards of the BHS protocol and the AAMI.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.647-651
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• 2004

Partial Least Squares (PLS) calibration performance has been systematically investigated by changing spectral resolutions of near-infrared (NIR) spectra. For this purpose, synthetic samples simulating naphtha were prepared to examine the calibration performance in complex chemical matrix. These samples were composed of $C_6-C_9$ normal paraffin, iso-paraffin, naphthene, and aromatic hydrocarbons. NIR spectra with four different resolutions of 4, 8, 16, and 32$cm^{-1}$ were collected and then PLS regression was performed. For PLS calibration, five different group compositions (such as total paraffin content) and six different pure components (such as benzene concentration) were selected. The overall results showed that at least 8$cm^{-1}$ resolution was required to resolve the complex chemical matrix such as naphtha. It was found that the influence of resolution on the PLS calibration was varied by the spectral features of a component.

• Journal of Digital Convergence
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• v.13 no.3
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• pp.107-115
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• 2015

The social commerce is an innovative and emerging transaction. It is the result of combination with transaction and social media technology. This study analyzes Korean college students' social commerce behavior through extending technology acceptance model(TAM) with social influence(SI). We confirmed all proposed hypotheses are significant and supported by the given data through PLS path modeling method with SmartPLS. It indicates that SI is an important factor influencing intention to use, so SI should be consider for theorists to enhance explanation and prediction of TAM and for practitioners to earn higher performances as well. Finally, based on the findings, suggestions for future studies are discussed.

• Journal of Korea Port Economic Association
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• v.31 no.4
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• pp.209-225
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• 2015

A freight forwarder plays an important role in global trade and logistics by connecting worldwide nodes such as shippers, ports, and airports. Most freight forwarders in Korea are small and do not provide a sophisticated and professional service. This study aims to develop a strategy for Korean freight forwarders to the world-class 3PLs which they have to establish the strategy on how shippers select their freight forwarders. We conducted a higher-order factor analysis using the PLS-SEM techniques on the SmartPLS program to confirm the importance and significance of each factor, while considering relevant previous research. The findings suggested that shippers chose their freight forwarders for international logistics activities primarily by the reliability and forwarder service factors. Therefore, freight forwarders in Korea have to strengthen confidence and widen their service to shippers in order to become leading logistics companies.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.61.2-61.2
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• 2013

우리나라 최초의 거대과학 장치인 포항방사광가속기(PLS)는 지난 16년(1994~2010) 동안 국내외 이용자에게 제3세대 방사광을 제공했다. 최초 2기의 빔라인을 시작으로 꾸준하게 빔라인 증설과 성능개선을 위해 노력해 왔다. 지속해서 늘어나는 방사광 이용자 수와 더욱더 좋은 수준의 방사광 요구에 부응하기 위하여 2009년부터 3년 동안 가속장치의 성능향상사업(PLS-II)을 마쳤다. PLS-II는 PLS 대비에너지와 빔전류는 3 GeV, 400 mA로 늘리는 반면 빔의 크기는 크게 줄이고 빔안정성을 개선한 고품질 X-선 방사광 발생장치이다. 2012년부터 16기의 삽입장치 빔라인을 포함한 30기의 빔라인을 가동하여 이용자 지원을 하고 있으며 초전도케비티 설치를 포함한 목표 성능의 확보에도 많은 노력을 기울이고 있다. 현재는 6 nm-rad의 빔에 미턴스, 3-GeV전자빔, 약 0.5 ${\mu}m-rms$ 빔안정도를 가진 200 mA Top-up 운전으로 빔을 제공 하고 있으며 2014년 말에는 저장전류 400 mA급의 PLS-II 목표치로 운전할 계획이다. 본 발표에서는 포항가속기의 25년 역사를 돌아보고 가속장치의 건설에 얽힌 이야기, 중요장치 그리고 운전과 빔제공에 관한 내용, 특히 핵심 운전가치인 빔안정성을 개선하고 유지하기 위한 노력을 빔운전 측면과 진공을 포함한 엔지지어링 측면에서 언급하고자 한다. PLS 건설부터 현재 운용 중인 30기의 빔라인에서 수행된 연구 성과의 통계에 대하여 훑어보고 X-선 산란과 광전자분광을 이용한 구조, 성분 및 물성분석, 그리고 이미징 등의 분야에서 나온 탁월한 연구 결과를 살펴본다. 앞으로 건설될 신규 빔라인과 빔라인의 향후 운영 방향을 소개한다. 마지막으로 지금 포항가속기연구소에서 건설 중인 제4세대 가속기(X-선 자유전자레이저) 프로젝트의 개요 및 건설 현황과 함께 앞으로 기대되는 새로운 과학에 대하여도 소개하고자 한다.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.556-558
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• 1996

PLS 2-GeV linac has 11 sets of high power klystron-modulator system as a main RF source for the beam acceleration. The modulators can provide 200-MW peak pulsed power(400-kV, 500-A) with a pulse width of $7.5{\mu}s$(ESW), a maximum pulse repetition rate of 120-Hz at the full power level. The DC power supply provides a 25-kV, 7-Adc and the charging system consists of a charging inductor, charging capacitor, and the diode for reverse current protection. The charged PFN voltage by a LC resonant charging method has two times of the DC high voltage and the pulsed power is delivered to the load by a thyratron switch. To reduced the press of high voltage lit thyratron switch, the command charging is the best method. In this article, the high voltage switch for the command charging method is tested to the start work and the system is presented with the experiment results of the trigger and operational characteristics.