• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.1
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• pp.77-87
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• 1996

In order to compare the difference of the measurement of delta aminolevulinic acid(${\delta}$-ALA) in urine between HPLC method(HALA) and colorimetric method(CALA), and also to provide useful information for the new diagnostic criteria of ${\delta}$-ALA in urine in lead poisoning, if at all possible in the future, authors studied 234 male lead workers who were selected from 7 storage battery factories, 3 secondary smelting industries, and 2 litharge making industries. Study subjects were selected on the basis of blood Zinc protoporphyrin(ZPP) level from low to high concentration to cover wide range of lead exposure. Study variables for this study were ${\delta}$-ALA measured by two different methods, blood lead(PbB), and blood ZPP. The results were as follows: 1. There was very high correlation between ${\delta}$-ALA measured by two method(r = 0.989 : HALA = -0.8194 + 0.8110 ${\times}$ CALA), but the value of CALA was measured about 2mg/L greater than HALA. 2. While the correlations of ${\delta}$-ALA by two method with blood lead and blood ZPP were 0.46 and 0.37 respectively, they were increased to 0.63 and 0.57 if ${\delta}$-ALA values were log-transformed. 3. Simple linear regression of ${\delta}$-ALA measured by two method on ZPP were as follows: CALA = 2.0421 + 0.0341 ${\times}$ ZPP ($R^2=0.1385$ p = 0.0001) HALA = 0.8006 + 0.0280 ${\times}$ ZPP ($R^2=0.1389$ p = 0.0001) 4. Simple linear regression of ${\delta}$-ALA measured by two method on PbB were as follows: CALA = - 0.4134 + 0.1545 ${\times}$ PbB ($R^2=0.2085$ p = 0.0001) HALA = -1.2893 + 0.1287 PbB ($R^2=0.2154$ p = 0.0001), 5. Simple linear regression of log-transformed ${\delta}$-ALA by two method on ZPP and PbB were as follows: logHALA = 0.3078 + 0.0060 ZPP ($R^2=0.3329$ p = 0.0001) logCALA = 1.0189 + 0.0044 ZPP ($R^2=0.3290$ p = 0.0001) logHALA = -0.0221 + 0.0246 PbB ($R^2=0.4046$ p = 0.0001) logCALA = 0.7662 + 0.0184 PbB ($R^2=0.4108$ p = 0.0001) 6. The cumulative percent of colorimetric method to detect lead workers whose value of PbS and ZPP were over screening level such as $40{\mu}/dl$ and $100{\mu}/dl$ respectively was higher than HPLC method if cut-off level of ${\delta}$-ALA for screening of lead poisoning was 5 mg/L. But if cut-off level of ${\delta}$-ALA measured by HPLC was reduced to 3 mg/L which is compatible to 5 mg/L of ${\delta}$-ALA measured by colorimetric method, there were good agreement between two methods and showed dose-response relationship with other lead exposure indices such as PbB and ZPP.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.12
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• pp.641-646
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• 2016

Soil organic matter (SOM) is an important soil component releasing nutrients to the plants and reducing risks of soil contamination to the human and ecosystem. Much attention has been recently paid to SOM investigation and management because SOM holds the most of carbon in the earth and sequestrate carbon as a sink tank. The first objective of the study was to investigate SOM of 495 soil samples taken at the Korea Soil Quality Monitoring Network. Soil samples were collected from 16 regions and 8 land use types. The second objective of the study was to find a relationship between the Tyurin method and loss-on-ignition (LOI) method for SOM. The means of SOM by Tyurin and LOI methods were 1.90 and 2.92 % (w/w), respectively. Land uses such as forest, religious area and park where organic matters continuously supply to normally showed higher SOMs than residential and school areas having sandy soils. A regression equation of the relationship between Tyurin and LOI methods was y(Tyurin) = 0.6257x(LOI) + 0.0602 (P-value < 0.001). The coefficient of determination was $R^2=0.749$, relatively linearly related. Although LOI may result in higher SOMs than the Tyurin method, LOI may be a preference for the SOM investigation if various kinds of land uses and many soil samples should be measured.

• The Korean Journal of Applied Statistics
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• v.27 no.7
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• pp.1229-1241
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• 2014

Most of sampling surveys have outliers and non-response missing values simultaneously. In that case, due to the effect of outliers, the result of imputation is not good enough to meet a given precision. To overcome this situation, outlier treatment should be conducted before imputation. In this paper in order for reducing the effect of outlier, we study outlier imputation methods and outlier weight adjustment methods. For the outlier detection, the method suggested by She and Owen (2011) is used. A small simulation study is conducted and for real data analysis, Monthly Labor Statistic and Briquette Consumption Survey Data are used.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.239-243
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• 2010

This paper deals with the optimum design criteria for the premium efficiency of 250 kW traction induction motor, using response surface methodology (RSM) and finite element method (FEM). The focus of this paper is found firstly a design solution through the comparison of torque according to rotor bar shape, rotor dimensions variations. And secondly a mixed resolution with central composite design (CCD) is introduced and analysis of variance (ANOVA) is conducted to determine the significance of the fitted regression model. The proposed procedure allows to be optimized the rotor copper bar shape, rotor slot, rotor dimensions starting from an existing motor or a preliminary design.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.105-110
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• 2004

This paper deals with the study of feasibility of rotary carbide tools in the machining of aluminium alloy. A rotary tool holder was designed and manufactured for this work. Experiments were performed using Taguchi methods and regression analysis to analyse the influence of various factors and their interactions on the cutting characteristics of rotary carbide tools during machining. The cutting force is influenced the most featly at the inclination angle. The surface roughness is influenced distinctly at depth of cut. It deduced an equation to predict cutting force and surface roughness. Hence, it could be concluded here that the proposed model agrees with the experimental data satisfactorily.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2009.05a
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• pp.114-119
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• 2009

본 논문에서는 수량화 방법과 AHP(Analytic Hierarchy Process) 기법을 사용하여 산사태 발생에 대한 통계적 예측모형을 구축하는데 목적이 있다. 수량화(Quantification) 방법은 질적변수에 수량을 부여하는 통계적 방법으로, 기 조사된 자료에 기반하여 분석을 수행하는 방법이다. 본 논문에서는 서구의 다변량분석 기법인 정준상관분석의 결과를 토대로 수량화 과정을 구체적으로 제안한다. 데이터에 기반한 수량화 방법과는 달리 AHP(Analytic Hierarchy Process) 기법은 일종의 다기준 의사결정을 위해 사용되는 기법으로, 설문자료에 기반한 분석법이다. 실제자료에 대한 분석으로 산사태 발생여부를 측정한 자료(한국지질자원연구원 제공)와 전문가 설문을 통해 수집된 자료를 이용하였다. 이들 자료에 대해 수량화 분석과 AHP분석을 통해 산사태 발생여부를 예측할 수 있는 두 종류의 평가표와 함께 로지스틱 회귀를 통한 통계적 예측모형을 개발하였으며, 두 모형간의 성능비교와 안정성 평가를 수행하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.303-305
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• 2014

관제구역 내 선박의 충돌을 예방할 수 있는 통항선박의 안전속력을 제시하기 위하여 선박의 충돌에 미치는 속력의 영향을 분석함으로써 속력과 충돌사고의 관련성을 통계적인 분석을 통하여 제시하였으며, 다중회귀분석법 및 정보기준의 최적화 기법을 적용하여 정량적인 측면에서 선박속력의 평균 및 분산이 잠재적 충돌사고에 미치는 영향을 검토하였다.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.195-196
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• 2015

태아의 소뇌는 임신주수에 따라 성장하며 소뇌횡직경 길이의 측정은 태아성장 예측의 중요한 지표로 활용하고 있다. 임신주수에 따른 태아 소뇌횡직경의 성장을 회귀곡선으로 표시하였고 선형회귀방정식에서 결정계수를 얻었다. 3차원초음파를 이용한 소뇌횡직경의 측정법은 통계적으로 유의(P<0.001)하였으며, 태령을 예측함에 유용하다는 것을 알 수 있었다. 또한 성장장애가 있는 태아의 경우에도 임신주수의 예측이 가능하다. 본 연구를 기초자료로 하여 지속적인 연구가 시행된다면 정확한 임신주수 예측에 유용할 것으로 기대한다.

• Journal of Families and Better Life
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• v.12 no.2
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• pp.50-59
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• 1994

본 연구에서는 가사노동분배에 영향을 준다고 믿어지는 결혼여부가 남녀임금격차에 미치는 영향을 조사하기 위하여 계속해서 직장에 근무하고 있는 기혼남녀와 미혼여성들의 임금수준과 인적자본의 수익들을 비교분석하였다 미국의 NLSY 데이터를 이용하여 Probit 분석과 최소자승법에 의한 회귀분석으로 자교를 분석하였으며 임금격차를 분리하는 과정은 Oaxaca(1973) 등이 사용한 절차와 같은 방법을 이용하였다 Probit 분석결가 기혼남성의 경 우 많은변수들이 지속적인 전일제 근무자가 될 가능성을 높이거나 낮추는 반면에 단지 소수의 변수들만이 기,미혼여성들에게 유의한 효과를 나타냈다 회귀분석결과 결혼여부보다는 성별관계가 임금을 낮추는 것으로 나타났으며 기혼남녀간 임금차액의 38~39%를 기혼남성과 미혼여성간 임금차액의 61~65%가 인적자본의 특성에 의해 설명되었다 본연구결과는 가정내 의 노동분배가 임금격차의 중요한 요소라는 Becker의 가설을 증명하지 못하고 있다 이는 여성의 미래 경제적지위를 염려해야 할 상당한 근거를 제시하며 인적자본의 양을 통제하였 을 때에도 임금격차가 만연하였기 때문에 인적자본의 질적인 면이 포함된 연구가 필요하다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.4
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• pp.14-20
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• 2005

This paper deals with the study of feasibility of rotary carbide tools in the machining of aluminium alloy. A rotary tool holder was designed and manufactured for this work. Experiments were performed using Taguchi methods and regression analysis to analyse the influence of various factors and their interactions on the cutting characteristics of rotary carbide tools during machining. The cutting force is influenced the most greatly at the inclination angle. The surface roughness is influenced distinctly at depth of cut. It deduced an equation to predict cutting force and surface roughness. Hence, it could be concluded here that the proposed model agrees with the experimental data satisfactorily.