• 한국통계학회:학술대회논문집
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• 한국통계학회 2005년도 추계 학술발표회 논문집
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• pp.167-173
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• 2005

This paper presents an autocorrelation test that is applicable to dynamic panel data models with serially correlated errors. The residual-based GMM t-test is a significance test that is applied after estimating a dynamic model by using the instrumental variable(IV) method and is directly applicable to any other consistently estimated residuals. Monte Carlo simulations show that the t-test has considerably more power than the $m_2$ test or the Sargan test under both forms of serial correlation (i.e., AR(1) and MA(1)).

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2017년도 임시총회 및 하계학술연구발표회
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• pp.137-137
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• 2017

• Journal of the Korean Statistical Society
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• 제34권4호
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• pp.367-375
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• 2005

This paper presents an autocorrelation test that is applicable to dynamic panel data models with serially correlated errors. The residual-based GMM t-test is a significance test that is applied after estimating a dynamic model by using the instrumental variable (IV) method and is directly applicable to any other consistently estimated residuals. Monte Carlo simulations show that the t-test has considerably more power than the $m_2$ test or the Sargan test under both forms of serial correlation (i.e., AR(1) and MA(1)).

• KSBB Journal
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• 제16권1호
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• pp.61-65
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• 2001

BTX를 배출하는 지역에서 얻어진 슬러지를 적절한 배지에 3개월 간 적응시킨 결과, benzene과 toluene을 빠르게 분해하는 MY컨소시엄와 p-, m-, o-xylene을 빠르게 분해하는 MA컨소시엄을 획득하였다. 균주의 동정결과 MA 및 MA컨소시엄의 주된 균주는 Rhodococcus ruber DSM 43338T과 Rhodococcus sp.로 밝혀졌다. BTX 단일성분의 분해속도 측정결과 benzene > toluene > o-xylene > p-xylene > m-xylene의 순으로 분해가 일어났다. MY 및 MY컨소시엄으 동시배양을 이용한 2-5종의 복합 BTX의 분해실험결과 대부분의 경우 108시간내에 완전히 분해되었으며, 각 혼합물의 조성에 따라 촉진 및 방해작용을 나타내었다. 분 연구에서 획득한 2종의 미생물컨소시엄은 BTX의 생물학적 처리에 매우 유용하게 사용될 수 있을 것으로 사료된다.

• International Journal of Automotive Technology
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• 제6권6호
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• pp.665-670
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• 2005

Nanocomposites of polypropylene with organically modified clays were compounded on a twin-screw extruder by two-step melt compounding of three components, i.e., polypropylene, maleic anhydride grafted polypropylene (PP-g-MA), and organically modified clay. The effect of PP-g-MA compatibilizers, including PH-200, Epolene-43, Polybond-3002, Polybond-3200, with a wide range of maleic anhydride (MA) content and molecular weight was examined. Morphologies of nanocomposites and their mechanical properties such as stiffness, strength, and impact resistance were investigated. X-ray diffraction patterns showed that the dispersion morphology of clay particles seemed to be determined in the first compounding step and the further dispersion of clays didn't occur in the second compounding step. As the ratio of PP-g-MA to clay increased, the clay particles were dispersed more uniformly in the matrix resin. As the dispersibility of clays was enhanced, the reinforcement effect of the clays increased, however impact resistance decreased.

• 한국환경보건학회지
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• 제50권1호
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• pp.25-35
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• 2024

Background: There are concerns about the health effects of various environmental pollution exposures among residents living near coal-fired power plants (CFPP). Objectives: This study attempted to compare the concentrations of heavy metals in blood and urine and those of urinary volatile organic compound (VOC) metabolites according to the residential separation distance. Methods: Participants in the study totaled 334 people who have lived for more than 10 years in areas within 10 km of a CFPP. The separation distance was analyzed in quartiles by dividing it into Q1 (88 people), Q2 (89 people), Q3 (89 people), and Q4 (68 people). We explained the purpose of this study to the participants and collected blood and urine after obtaining signatures on a participation agreement. Results: The study participants were 102 males (30.5%) and 232 females (69.5%), with an average age of 71. The average length of residence and distance were 43.8 years and 4,800 meters. The geometric mean concentrations of Pb, Cd, and Hg in blood and As and Cd in urine were respective 1.35 ㎍/dL, 1.43 ㎍/L, 3.16 ㎍/L. They were 167.88 ㎍/g for creatinine and 1.58 ㎍/g creatinine. The metabolite concentrations of VOCs were 50.67 ㎍/g creatinine in t, t-muconic acid (t, t-MA), 10.73 ㎍/g creatinine in benzyl mercapturic acid, 317.05 ㎍/g creatinine in phenylglyoxylic acid, 123.55 ㎍/g creatinine in methylhippuric acid, and 190.82 ㎍/g creatinine in mandelic acid. The concentration of Pb in the blood and Cd and t, t-MA in the urine of residents within affected area of the CFPP showed statistically significant differences among distance groups. Conclusions: The concentration of urinary VOCs metabolites, especially t, t-MA, differed according to the distance groups of residents within the affected area of CFPP (p<0.05).

• 자원환경지질
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• 제29권2호
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• pp.151-158
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• 1996

Rb-Sr isochron ages, Sr and Nd isotopic compositions were determined for late Cretaceous granophyre on the Haenam-Wando areas, the southwestern part of the Yeongdong-Kwangju depression in Korea. The granophyre in the Haenam-Wando areas are distributed in the shape of a resurgent cauldron. Five samples of Haenam granophyre give a defined Rb-Sr whole rock isochron age of $75.7{\pm}7.2Ma$ and Sr initial ratio of $0.70826{\pm}0.00020(2{\sigma})$. Plagioclase, orthoclase and whole rock of Haenam granophyre give a defined Rb-Sr whole rock-mineral isochron age of $67.0{\pm}5.8Ma$ and Sr initial ratio of $0.708880{\pm}0.00028(2{\sigma})$. Five samples of Wando granophyre give a defined Rb-Sr whole rock isochron age of $70.6{\pm}3.3Ma$ and Sr initial ratio of $0.70850{\pm}0.00088(2{\sigma})$. Eight samples of Haenam granophyre give a defined Nd isotope ratios of 0.512180~0.512259 and ${\varepsilon}Nd$ (T) values of -6.53~-8.15, ${\varepsilon}Sr$ (T) values of +51.49~+66.48 and model age of 1.28~1.60 Ga. Four samples of Wando granophyre give a defined Nd isotope ratios of 0.512228~0.512289 and ${\varepsilon}Nd$ (T) values of -6.74~-8.00, ${\varepsilon}Sr$ (T) values of +54.88~+78.98 and model age of 1.14~1.42 Ga.

• ETRI Journal
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• 제37권3호
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• pp.450-459
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• 2015

Small cell networks, as an important evolution path for next-generation cellular networks, have drawn much attention. Different from the traditional base stations (BSs) always-on model, we proposed a BSs on-off model, where a new, simple expression for the probabilities of active BSs in a heterogeneous network is derived. This model is more suitable for application in practical networks. Based on this, we develop an analytical framework for the performance evaluation of small cell networks, adopting stochastic geometry theory. We derive the system coverage probability; average energy efficiency (AEE) and average uplink power consumption (AUPC) for different association strategies; maximum biased received power (MaBRP); and minimum association distance (MiAD). It is analytically shown that MaBRP is beneficial for coverage but will have some loss in energy saving. On the contrary, MiAD is not advocated from the point of coverage but is more energy efficient. The simulation results show that the use of range expansion in MaBRP helps to save energy but that this is not so in MiAD. Furthermore, we can achieve an optimal AEE by establishing an appropriate density of small cells.

• Journal of Oral Medicine and Pain
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• 제46권1호
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• pp.1-8
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• 2021

Purpose: The purpose of this study was to assess the relationship between psychological factors and symptoms of oral mucosal diseases by means of the revised version of the Minnesota Multiphasic Personality Inventory (MMPI-2). Methods: Three hundred and eighteen college students in Gyeonggi-do completed the MMPI-2 and a questionnaire related to symptoms of oral mucosal diseases and collected data were analyzed by Student's t-test and one way ANOVA. Results: Subjects who have experienced herpetic stomatitis revealed significantly higher mean values of T-scores than subjects who have not on hypochondriasis (Hs) and hysteria (Hy) clinical scales of the MMPI-2 (p<0.05). In comparison with subjects who have had recurrent aphthous ulceration, subjects who have not had it manifested significantly higher elevations on the schizophrenia (Sc) clinical scale (p<0.05). Subjects who have suffered oral lichen planus (OLP) showed significantly higher mean values of T-scores than subjects who have not on paranoia (Pa) (p<0.05) and hypomania (Ma) (p<0.01) clinical scales. Mean values of T-scores on Ma clinical scale were significantly higher in subjects having experienced glossodynia than in subjects having not experienced (p<0.05). Subjects having felt taste disturbance exhibited significantly higher elevations on Hs (p<0.0001) and Hy (p<0.01) clinical scales compared to subjects having not. Conclusions: Symptoms of oral mucosal diseases such as herpetic stomatitis, taste disturbance, OLP, and glossodynia were found to be related to Hs, Hy, Pa, Ma clinical scales of the MMPI-2. Therefore, comprehensive psychological evaluations of those oral mucosal diseases may be beneficial in a therapeutic approach.

• 한국약용작물학회지
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• 제4권1호
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• pp.52-57
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• 1996

국내에 재배되는 마(Dioscorea batatas) 주요품종으로는 식용으로 널리 쓰이는 단마, 약용으로 이용되는 장마 그리고 최근 식용마로 도입육성된 축근종(筑根種) 등이 있다. 본 연구는 이들 세종류의 마 주요품종을 대상으로 동위효소 분석과 생육특성 및 수량성을 비교하여 얻어진 결과이다. 1. 마 주요품종의 동위효소 분석 마 주요품종의 동위효소를 분석한 결과 단백질의 band pattern은 잎, 엽병, 줄기 모두에서 Band의 수와 위치의 차이를 보였다. Peroxidase의 동위효소는 잎과 엽병은 거의 동일하게 조사되었으나 줄기조직에 의해 구분이 가능하였다. 그리고 Esterase의 경우는 잎과 엽병, 줄기 모두에서 band pattern의 차이를 보여 품종간 구분이 가능하였다. 2. 마 주요품종의 생육특성 및 수량비교 엽형비교에서 단마와 장마는 상위엽이 피침형이고 축근종(筑根種)은 장심장형 이었으며, 엽서는 장마와 단마의 상위엽이 호. 대생을 보인반면 축근종(筑根種)은 대생이었다. 뿌리 생육과 수량성 비교에서 괴 근수가 단마 1.2개, 장마 1.3개지만 축근종(筑根種)은 1개였다. 괴근장은 단마와 장마가 각각 30cm와 51cm로 길었지만 축근종(筑根種)은 9.7cm로 짧았다. 괴근수량은 단마가 2,751kg/10a로 가장 높았고 장마가 2,288kg/10a였으며, 축근종(筑根種)은 1,785kg/10a였다. 축근종(筑根種)의 수량은 단마와 장마에 비하여 적었으나 단괴형이어서 기계화 수확에 유리한 품종으로 생각되었다.