• The Korean Journal of Applied Statistics
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• v.27 no.4
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• pp.553-560
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• 2014

This paper deals with estimable functions of parameters of less than full rank linear model. In general, the parameters of an overspecified model are not uniquely determined by least squares solutions. It discusses how to formulate linear estimable functions as functions of parameters in the model and shows how to use projection matrices to check out whether a parameter or function of the pamameters is estimable. It also presents a method to form a basis set of estimable functions using linearly independent characteristic vectors generating the row space of the model matrix.

• Communications for Statistical Applications and Methods
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• v.5 no.3
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• pp.623-632
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• 1998

이원혼합모형에서 고정효과의 추정가능한 함수에 대한 신뢰구간을 구하는 경우에 어떤 분산성분추정량을 선택하는 것이 가장 바람직한가를 모의실험을 통하여 살펴본다 혼합모형에서는 t-분포와 일반화최소제곱추정량을 사용하여 신뢰구간을 구할 수 있는데, 일반적으로 분산성분을 알 수 없기 때문에 분산성분을 반드시 추정하여야만 한다. 이 경우 분산성분의 추정량으로 가장 많이 사용되는 추정량들인 Henderson의 방법 III 추정량, 사전추측값이 1인 MINQUE 추정량, MLE(최우추정량), REMLE(제한최우추정량)를 이용하여 분산행렬을 추정하고, 신뢰구간의 포함범위확률과 평균길이를 모의실험을 통하여 살펴본다. 모의실험의 결과는 4가지 추정량 모두 비슷한 신뢰구간의 포함범위확률과 평균길이를 갖는 것으로 판명되었다.

• Journal of Labour Economics
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• v.37 no.2
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• pp.105-121
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• 2014

Since the end of the World War II, the population explosion of developing countries has been a global concern. However, the impact of family planning program effort to reduce fertility is difficult to measure, as the effort level is endogenously determined. This paper studies if the family planning program impact is substantial and statistically significant in fertility reduction using fixed effect analysis. The fixed effect estimate shows that there is little impact of family planning program effort on fertility. Only the higher income countries showed significant negative impact.

• The Korean Journal of Applied Statistics
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• v.30 no.3
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• pp.335-344
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• 2017

This paper discusses a method of analyzing data from split-plot experiments by projections. The assumed model for data has two experimental errors due to two different experimental sizes and some random components in treatment effects. Residual random models are constructed to obtain sums of squares due to random effects. Expectations of sums of squares are obtained by Hartley's synthesis. Estimable functions of fixed effects are discussed.

• Journal of Biomedical Engineering Research
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• v.21 no.6
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• pp.599-606
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• 2000

고정체 나사산 형상이 식립된 고정체를 둘러싸고 있는 턱 뼈에서 발생된 응력분포에 미치는 영향과 효과적인 나사산 형상을 결정하기 위해서 다양한 치아 고정체 형상에 대해서 응력해석을 수행하였다. 나사산 골 한쪽 부위에 라운딩이 된 형상의 고정체에서 발생된 응력분포는 다른 나사산 형상의 고정체에서 발생된 응력분포보다 더 효과적으로 나타났다. 이 해석 결과를 근거로 최적의 고정체 치수를 결정하기 위해서 나사산 끝단의 폭, 나사산 높이, 그리고 가해지는 하중의 방향 등과 같은 설계 변수의 변화에 따른 응력해석이 수행되었다. 최대 응력 집중은 고정체 나사산의 첫단 부위에서 발생하였으며, 100 N의 15도 경사하중이 가해졌을 때 발생된 최대 등가응력은 동일 크기의 수식하중보다 2배 정도 더 높게 나타났다. 그리고 나사산 끝단의 폭과 나사산 높이 사이의 연관성에 관련된 해석결과에서 나사산 끝단의 폭과 나사산 높이 사이의 연관성 효과는 무시할 만큼 작다는 것을 알았다. 고정체의 나사산 피치에 대한 나사산 끝단의 폭의 비와 나사산 높이의 비가 각각 0.5와 0.46일 때 다른 고정체의 치수들보다 더 효과적인 응력분포가 나타났다

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.199-211
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• 2017

The notable findings are as follow: First, men show higher level of perceiving open marriage, sex-role, acceptance of extra-marital relationship and intention of extra-marital sex than that of women. Second, the effects of men's perception of sex-role and open marriage, and the acceptance of extra-marital relationship have direct effects on their intention of extra-marital sex. The acceptance of extra-marital relationship shows the mediation effect on the path between that of open marriage and extra-marital sex among men. However, men's perception of sex-role does not affect the acceptance of extra-marital relationship. Lastly, women's perception of sex-role and open marriage, and the acceptance of extra-marital relationship directly influence the intention of extra-marital sex each, including the mediating effect of accepting extra-marital relationship between that of open marriage and extra-marital sex which are similar to the men's trend. Women's perception of sex-role show the direct effect on the acceptance of extra-marital relationship unlike man's trend. Therefore, the fact demonstrates that the effect of perceiving of sex-role on the intention of extra-marital sex is different according to gender. Some practical and political implications are discussed based on the study's findings.

• KDI Journal of Economic Policy
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• v.28 no.1
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• pp.117-144
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• 2006

This study is to analyze the existence of the real buffer effect that reflects the effect of beginning-of-period inventory stocks effect on the demand for fixed investment, and the financial buffer effect indicates the substitution effect between end-of-period inventory stock and the source of financing for fixed investment. I use panel data of 361 Korean listed non-financial firms during 1990-2003. After the crisis, it also observed whether the relationship between inventory stocks and fixed investment has altered or not. I review the theoretical connection between inventory stock and fixed investment through the paper by Bo(2004) and estimate the investment model by the method of GMM-SYS. The results show negative relation between end-of-period inventory stock and fixed investment in the whole period and each period classified, also it confirms that the relation between fixed investment and end-of-period investment is significantly negative. It can be interpreted through two aspects that firms not only use inventory stock as a buffer in response to unexpectedly high demand, but also utilize inventory stock as a source of financing for fixed investment. The results imply that firm's decision-making is much correlated with production-and-inventory stock adjustment, decision-making about fixed investment, and decision-making about financial affairs.

• Korean Journal of Food Science and Technology
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• v.11 no.4
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• pp.283-290
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• 1979

Partially purified ${\beta}-fructosidase$ (inulase) from Kluyveromyces fragilis was immobilized on Tygon tube and aminoethyl-cellulose, respectively and both preparations were characterized. Silanization of Tygon tube in chloroform at $65^{\circ}C$ and treatment with 10 % glutaraldehyde were critical for the immobilization of inulase on Tygon tube, while 2 % glutaraldehyde was effective for the immobilization on aminoethyl-cellulose. The derivative of Tygon tube showed 11.5 units of inulase activity per g of dried matrix with retention of 22.5 % of original activity against inulin, whereas one of aminoethyl-cellulose showed 39.3 units per g of dired matrix with 53.4 % of retention. Studies of enzyme stability, pH and temperature dependences, and $K_m$ values are presented for inulase and invertase activities of both immobilized enzymes.

• The Journal of the Korea Contents Association
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• v.9 no.3
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• pp.225-231
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• 2009

The purpose of the current study was to compare radiation dose of 64MDCT performed with automatic exposure control (AEC) with manual selection fixed tube current. We evaluated the CT scans of phantom of the chest and abdomen using the fixed tube current and AEC technique. Objective image noise shown as the standard deviation of CT value in Hounsfield units was measured on the obtained images. Compared with fixed tube current, AEC resulted in reduction of the chest and abdomen in the CTDIvol (35.2%, 5.9%) and DLP (49.3%, 3.2%). Compared with manually selected fixed tube current, AEC resulted in reduced radiation dose at MDCT study of chest and abdomen.

• KDI Journal of Economic Policy
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• v.32 no.2
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• pp.27-53
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• 2010

This paper examines whether and how much vocational training raises an individual's earnings in Korea, using the Economically Active Population Survey. To overcome endogeneity of training, we apply fixed-effects and propensity-score matching (PSM) methods. Fixed-effects (PSM) results suggest that work-related training received in the previous one year increases a worker's monthly earnings by 2.6 to 4.7 (7.5 to 9.8) percent. Taken altogether, work-related training enhances a worker's earnings by a minimum of 2.6 and a maximum of 9.8 percent in Korea.