• Survey Research
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• v.10 no.1
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• pp.169-186
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• 2009

The propensity score method is used to minimize the bias level in social survey, which comes from nonresponse. The theoretical concept and the background of the propensity score method is discussed first. The propensity score method was first applied in the epidemiology observational study. I have summarized the process of the three propensity score methods that were used to reduce estimation bias in this study. Matching by propensity score is applied to the relatively large control group. Subclassification has the advantage of using whole control group data and regression adjustment is applied to multiple covariates as well as propensity score of each unit is computable and usable. Lastly, the application procedures of propensity score method to reduce the nonresponse bias is suggested and its applicability to real situation is reviewed with the existing data.

• Journal of the Korean Society of Radiology
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• v.10 no.3
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• pp.171-180
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• 2016

This study was to evaluate the change in characteristics of concentration of ozone after exposure to high energy radiation in linac room. Background ozone concentration of linac room was measured and compared to ozone concentration around linac room. Background ozone concentration of linac room was mean $17.4{\pm}7.9ppb$. It was 50% of the ozone concentration($36.8{\pm}22.3ppb$) around linac room(p<0.05). The concentration of ozone after exposure to high energy radiation in linac room was elevated to double of background ozone level, intensity after exposure. with exposure time concentration of ozone increased proportionally. It showed maximum level at 130~180seconds and slowed a tendency to saturate. It required more than 10 minutes for ozone concentration in linac room to drop to ozone concentration around linac room. The concentration of ozone after exposure to high energy radiation is high enough to cause specific physical symptoms, such as acute dyspnea or chest pain due to dry cough. Exposure to high concentration of ozone in sealed linac room can aggravate pulmonary disease, so special attention is needed.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.1
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• pp.111-117
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• 2000

In the KRISO cavitation tunnel, the acoustic characteristics for the measurement of underwater noise are investigated, The background noise is measured and analyzed up to 100kHz at various test conditions. The noise level of the KRISO cavitation tunnel is compared with those of the other cavitation tunnels which have been designed for the noise study[HYKAT(Germany), GTH(France), etc.]. In order to investigate the background noise source. the coherence between structural vibration and noise level is analyzed using the B&K 3550 FFT analyzer. The experimental results show the possibility of the noise study and suggest the improvement plan.

• Journal of the Korean Society for information Management
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• v.26 no.2
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• pp.43-63
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• 2009

Recently in Korea, the need has increased for the systematization of the qualifications of subject specialist librarians who have both knowledge and work experience on specific subject. The purpose of this study is to analyze the domestic situation of subject special library services as well as the education backgrounds or work experience of current subject librarians in Korea. At the end, the study attempts to suggest an appropriate framework for the qualification system establishment and operation in Korea based on the supply and demand analysis of domestic subject specialist librarians.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.141-154
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• 1996

Intrinsic layers of homoepitaxial InP grown by the hydride vapor phase epitaxy (VPE) technique were investigated by Fourier-transform photoluminescence(FTPL) and variable temperature Hall measurements. The effect of process variables (i.e., source zone temperature and inlet mole fractions of HCl and $PH_{3}$) on the backgroudn impurity levels was investigated. The background carrier concentration was found to decrease with decreasing source zone temperature and increasing HCl, but was relatively independent of $PH_{3}$ for the range of mole fraction studied. The presence of background donors and acceptors was clearly verified in the FTPL spectra, and the major impurities were tentatively identified as Si donors and Zn acceptors as well as some unidentified acceptors.

• ETRI Journal
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• v.8 no.4
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• pp.133-143
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• 1986

본 연구에서는 새로운 서비스 / 상품에 대한 수요예측을 좀더 쉽고, 가능한 합리적으로 수행할 수 있게 하기위하여 개발된 MPS-NS개발의 기본배경, MPS-NS의 구성과 예측 알고리즘 등을 중심으로 소개하였다. MPS-NS는 표본조사를 통한 설문조사 방법을 새로운 서비스 / 상품의 수요예측에 적용할 수 있도록 만들어진 새로운 서비스 시장 침투 분석S/W이다.

• Aerospace Industry
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• v.69
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• pp.52-55
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• 1999

미국에서의 항공기 운항업계에 대한 규제완화 여파로 우리나라 등 각국에도 규제 완화의 바람이 불고 있다. 항공기 제조업계는 기업의 통합과 구조 조정이 급진전하여 소수 정예의 과점 상황으로 나아가는가 하면 운항업계에서는 대규모 회사에 의한 독과점 체제가 무너지고 있다. 이런 배경 아래 항공기 사고에 대해서도 사고 조사가 제3자에 의하여 공정히 행해질 것을 바라는 소리가 높다.

• Digital Contents
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• no.9 s.100
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• pp.64-69
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• 2001

데이터마이닝 기술은 1990년대 전반에 걸쳐 기초연구가 본격화돼 최근 2~3년간 부쩍 산업계에서 실용화되기 시작했다. 필자가 조사한 범위에서는 금융이나 유통 등의 분야에서 마케팅 조사를 하는데 적용하는 것이 주류였으며, 기타 제조업이나 통신 서비스 업종에서도 품질관리 및 고객관리 등에 적용시키고 있다. 이처럼 데이터마이닝 기술이 급속한 보급을 보이고 있는 배경에는 데이터가 점차 디지털화 되어 가고 데이터베이스 축적에 의해 그 대상이 되는 데이터를 풍부하게 얻을 수 있게 되었다는 점이다.

• Proceedings of the Korean Society for Information Management Conference
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• 2003.08a
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• pp.107-116
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• 2003

본 연구는 블리스의 서지 분류법의 탄생배경을 알아보고자 한다. 이를 위해서 블리스의 생애와 학문적 계보를 조사하였다. 또한 서지 분류법의 특성 및 분류체계 그리고 현재의 상황에 대해 살펴보았다. 이러한 조사와 분석을 통해서 서지 분류법의 유용성 및 지속적인 연구의 기초를 제시하는데 목적이 있다.

• The tire
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• s.86
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• pp.13-16
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• 1980

미국 상무성에서는 미국경제에서 타이어 공업의 중요성을 고려하여 타이어 공업의 역사적 배경, 타이어공업에 영향을 주는 대외적인 요인, 타이어에 대한 각종통계자료, 국내 타이어 공업의 위축에 대한 원인 등에 대하여 조사분석을 하였다. 미국 상무성의 Chemical and Rubber program division의 David H.Blank가 1979년 4월에 이 조사분석 결과를 발표하였다.