산화물 혼합상이 페라이트계 P/M스테인리스강의 고온산화 및 전기저항 안정성에 미치는 영향

박진우,고병현,정우영,박동규,안인섭,Park, Jin-Woo,Ko, Byung-Hyun,Jung, Woo-young,Park, Dong-Kyu,Ahn, In-Shup 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.3

In order to improve the high-temperature oxidation stability, sintered 434L stainless steel is studied, focusing on the effect of the addition of metallic oxides to form stable oxide films on the inner particle surface. The green compacts of Fecralloy powder or amorphous silica are added on STS434L and oxidized at $950^{\circ}C$ up to 210 h. The weight change ratio of 434L with amorphous silica is higher than that of 434L mixed with Fecralloy, and the weight increase follows a parabolic law, which implies that the oxide film grows according to oxide diffusion through the densely formed oxide film. In the case of 434L mixed with Fecralloy, the elements in the matrix diffuse through the grain boundaries and form $Al_2O_3$ and Fe-Cr oxides. Stable high temperature corrosion resistance and electrical resistivity are obtained for STS434L mixed with Fecralloy.

타당성 평가가 보완된 모델 운용상의 전투실험 모의분석 절차 연구

박진우,김능진,강성진,서혁,Park, Jin-Woo,Kim, Nung-Jin,Kang, Sung-Jin,Soo, Hyuk 한국시뮬레이션학회 2010 한국시뮬레이션학회 논문지 Vol.19 No.4

Currently, our society has been changed from the industrial society to the information society. As the war progresses to Information Warfare, Network-Centric Warfare, Long-Range Precision Engagement and Robot Warfare, the military should advance to High-tech Scientific force. For this creation of the war potential, it is regarded as the warfighting experiment is a critical method. Surely it is rational that LVC(Live Virtual Constructive simulation) is desirable to make the warfighting experiment. But because it is limited by the cost, the time, the place and the resource, the constructive simulation(M&S : Modeling&Simulation) is a good tool to solve those problems. There are some studies about the evaluation process for developing the model, but it is unsatisfying in the process of the constructive simulations' operation. This study focuses on the way of constructive simulation operation, which is supplied with the evaluation process(VV&A : Verification Validation & Accreditation). We introduce the example of the rear area operation simulation for "appropriateness evaluation to the organization of logistic corps" by the AWAM(Army Weapon Analysis Model). This study presents the effective methods of the constructive simulations, which is based on the reliable evaluation process, so it will contribute to the warfighting experiments.

P/M Fecralloy의 성형성 및 전기저항특성 향상에 관한 연구

박진우,고병현,정우영,박동규,안인섭,Park, Jin-Woo,Ko, Byung-Hyun,Jung, Woo-Young,Park, Dong-Kyu,Ahn, In-Shup 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.6

The Fe-Cr-Al alloy system shows an excellent heat resistance because of the formation of an $Al_2O_3$ film on the metal surface in an oxidizing atmosphere at high temperatures up to $1400^{\circ}C$. The Fecralloy needs an additive that can act as a binder because of its bad compactability. In this study, the green compacts of STS434L and Al powder added to Fecralloy are oxidized at $950^{\circ}C$ for up to 210 h. Fecralloy and Al is mixed by two types of ball milling. One is vented to air and the other was performed in a sealed jar. In the case of Al addition, there are no significant changes in the electrical resistance. Before the oxidation test, Al oxides are present in the Fecralloy surface, as determined from the energy dispersive spectroscopy results. The addition of Al improves the compactability because of an increased density, and the addition of STS434L increases the electrical resistivity by forming a composite oxide.

P/M Fecralloy 성형체의 고온산화 및 전기저항 안정성에 미치는 SiO₂ 첨가 효과

박진우,옥진욱,정우영,박동규,안인섭,Park, Jin-Woo,Ok, Jin-Uk,Jung, Woo-young,Park, Dong-kyu,Ahn, In-Shup 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.4

A metallic oxide layer of a heat-resistant element contributes to the high-temperature oxidation resistance by delaying the oxidation and has a positive effect on the increase in electrical resistivity. In this study, green compacts of Fecralloy powder mixed with amorphous and crystalline silica are oxidized at $950^{\circ}C$ for up to 210 h in order to evaluate the effect of metal oxide on the oxidation and electrical resistivity. The weight change ratio increases as per a parabolic law, and the increase is larger than that observed for Fecralloy owing to the formation of Fe-Si, Fe-Cr composite oxide, and $Al_2O_3$ upon the addition of Si oxide. Si oxides promote the formation of $Al_2O_3$ and Cr oxide at the grain boundary, and obstruct neck formation and the growth of Fecralloy particles to ensure stable electrical resistivity.

PDGF-BB 적용시간이 decalcified dentin에서의 치은섬유아세포의 증식에 대한 효과

박진우,이재목,서조영,Park, Jin-Woo,Lee, Jae-Mok,Sun, Jo-Young 대한치주과학회 1996 Journal of Periodontal & Implant Science Vol.26 No.4

Platelet-derived growth factor(PDGF) is one of the polypeptide growth fators. PDGF has been reported as a biological mediator which regulates activities of wound healing process including the cell proliferation, migration and metabolism. Recent studies indicated that demineralized root surface as the primary site for growth factor application has advantages over other application method, especially due to binding capacity of growth factor for exposed matrix component of deminera1ized dentin surface. The purpose of this study is to evaluate optimal application time of PDGF-BB on proliferation of human gingival fibroblasts using deminera1ized dentin surface as primary application site. Human gingival fibroblasts and dentin slabs were prepared from the first premolar tooth extracted for the orthodontic treatment, cells were cultured in DMEM/I0% FBS at the $37^{\circ}C$, 5% CO2 incubator. All of the dentin slabs were preconditioned with Tetracycline HCI(100mg/ml) solution and rinsed in PBS. In the cell proliferation experiment, experimental group was immersed in DMEM containing 10% FBS, 50ng/rnl PDGF-BB during different time(30sec, 1, 2, 4, 8 minutes) and dried. Cells at concentration of $1{\times}10^5$cells/ml were seeded in each culture well which contained dentin slabs and incubated for 6 hours. Then, all of the dentin slabs were moved into new 24 well culture dish and incubated for 24, 48, 72 hours. The cell counting was done by hemocytometer with inverted phase contrast microscope after trypsinization. The results were as follows : The application of PDGF-BB for 1, 2 min slightly increased the number of gingival fibroblasts, and the application of PDGF-BB for 4, 8 min prominently increased the number of gingival fibroblasts. The application of PDGF-BB for 4 min showed maximum proliferation rate of gingival fibroblasts at 24, 48, 72 hours, and the application of PDGF-BB for 8 min showed less proliferation rate of gingival fibroblasts compared to the application of PDGF-BB for 4 min at 24, 48, 72 hours. In conclusion, the application of PDGF-BB for 4 min appeared to be optimal to obtain maximum proliferation of gingival fibroblasts using demineralized dentin surface as primary applicaton site of PDGF-BB.

이상점을 고려한 다변량 층화

박진우,윤석훈,Park, Jin-Woo,Yun, Seok-Hoon 한국통계학회 2008 응용통계연구 Vol.21 No.3

Most of the sample surveys conducted by several statistics preparation agencies are multipurpose surveys inquiring into several distinguishing items through a single sample. In a multipurpose sample design, the stratification tends to be very complex since the stratification variables which are both multivariate and heterogeneous must be considered collectively. In this paper we point out an outlier effect in a multivariate stratification to which the K-means clustering method is applied and propose to consider outliers prior to the stratification step. We also show an empirical stratification effect under consideration of outliers through a case study of sample design for The Rural Living Indicators. 여러 통계작성기관에서 실시하는 대부분의 표본조사들은 하나의 표본을 통해 서로 다른 여러 항목들을 조사하는 다목적조사이다. 다목적표본설계에서 층화변수들은 다변량이고 또한 서로 이질적인 속성을 지니는 관심변수들을 종합적으로 고려해야 하므로 층화는 매우 복잡한 양상을 띤다. 본 연구는 K-평균군집법을 적용한 다변량 층화에서 이상점의 효과를 지적하고, 층화 단계에서 사전에 이상점을 고려할 것을 제안하는 연구이다. 농촌생활지표조사를 위한 표본설계의 사례를 통해 이상점을 고려한 층화의 효과를 실증적으로 보인다.

통계기반 정책사례 연구: 주택가격지수 통계의 구축, 개선, 활용을 중심으로

박진우,Park, Jin-Woo 한국통계학회 2009 응용통계연구 Vol.22 No.3

사회가 민주화, 선진화되어감에 따라 합리적인 정책과정의 중요성이 강조되어 이른바, 증거기반 정책(evidence-based policy) 이 정책 분야에서의 중요한 화두로 떠오르게 되었다. 증거기반 정책, 그 중에서도 통계에 기반을 둔 정책에 관한 관심이 고조되고 있기는 하지만 구체적인 정책분야에서 통계가 어떻게 사용되고 있는지에 대한 구체적인 사례들이 소개된 것은 그다지 많지 않다. 본 연구의 목적은, 현재 국민은행이 작성하여 공표하는 주택가격지수가 구축, 발전되어 온 과정을 더듬으면서 구체적으로 통계가 어떻게 주택정책의 기반으로 활용되어 왔는지를 조명하는데 있다. 시기별 주택가격지수의 통계적 특징 및 문제점들을 지적하고, 이러한 문제점들이 개선되는 과정을 살펴본다. 아울러 주택가격지수가 구체적인 부동산 관련 정책과정에서 어떻게 활용 되는지를 소개한다. Democratization and advancement of a society requires the Government's commitment to evidence-based policy. Though statistic is known as one of the best available evidence, there has been only a few case studies to tell real stories about using statistics for policy making. The object of this study is to suggest some real stories about using the Housing Purchase Price Survey for some property policies. By reviewing the origin and development of the survey, we evaluate the design and analysis strategies adopted in the survey. In addition, we describe how the Housing Purchase Price Indices have been used by the Government for some property policies.

국민건강영양조사 표본설계를 위한 추출틀 구축

박진우,변종석,박민규,Park, Jin-Woo,Byun, Jong-Seok,Park, Min-Kyu 한국통계학회 2010 응용통계연구 Vol.23 No.5

제 5기 국민건강영양조사(2010년.2012년)를 위한 표본설계의 여건은 과거에 비해 불리한데, 무엇보다 과거와 같은 추출틀 마련이 여의치 않다는 점이 두드러진다. 제5기 조사를 위한 표본설계 시기가 인구주택총조사 주기와 맞지 않음으로 인해 과거의 총조사 자료를 그대로 추출틀로 사용한다면 어쩔 수 없이 추출틀오차의 문제가 발생하게 될 것이기 때문이다. 이를 극복하기 위한 현실적인 방안을 마련하는 것은 실용적인 면에서 매우 절실한 문제라고 할 수 있다. 본 연구의 목적은 인구주택총조사 자료가 낡아 현재의 모집단 상황을 제대로 대표할 수 없는 상황에서 이를 극복할 수 있는 효과적인 추출틀을 마련하는 데 있다. 본 연구에서는 추출틀의 포함률을 높이기 위한 방안으로 아파트 가구와 일반가구(단독주택, 연립주택, 다세대주택 등)를 분리하여 각각에 대해 서로 다른 자료를 활용하는 방안을 도입한다. 다시 말해 표본설계를 위해 여러 개의 추출틀을 사용하는 방안을 제시한다. One of the problems in designing the fifth Korean National Health and Nutrition Examination Survey(KNHNES) is the lack of an appropriate sampling frame. Due to the significant time difference, we expect eight severe sampling frame errors if we use the sampling frame obtained from the latest population and housing census that was conducted in 2005. Thus, the construction of an appropriate sampling frame for the fifth KNHNES is crucial for a successful survey. We considered the construction of a sampling frame that overcomes the limitations of the 2005 population and housing census based frame. For the construction of eight new sampling frames, we considered the use of multiple sampling frames in which the frame for the apartment households and the frame for the general households are obtained from different sources.

탈단백 우골의 골이식 대체재로서의 특성에 대한 평가;세 종류의 골 대체재의 기본 특성에 대한 비교분석

박진우,Park, Jin-Woo 대한치주과학회 2005 Journal of Periodontal & Implant Science Vol.35 No.4

Bovine bone-derived bone substitutes are widely used for treatment of bone defects in dental and orthopedic regenerative surgery. The purpose of this study was to evaluate the basic characteristics of deproteinized bovine bone mineral as a bone graft substitute. Commercially available products from three different bovine bone minerals-Bio-Oss(GeistlichPharma, Switzerland), BBP(Oscotec. Korea), Osteograf/N-300(Dentsply Friadent Ceramed, USA) - were investigated. They were evaluated by scanning electron microscopy(SEM), energy dispersive X-ray spectrometer(EDS), surface area analysis(BET), and Kjeldahl protein analysis. Cell viability on different products was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assay. The results of this study indicated that each bone substitute displayed distinct surface properties. Furthermore, Kjeldahl protein analysis indicated that residual crude proteins are present in deproteinized bovine bone mineral. BBP showed relatively large amount of residual protein, which indicated that the possibility of disease transmission can not be safely ruled out. Based on the results of this study, it is suggested that active quality management is strongly needed in operations that involve processing bovine bone tissue for medical use.

운모기판을 이용한 다결정 Si 전이막 성장 연구

박진우,엄지혜,안병태,정영권,Park Jin Woo,Eom Ji Hye,Ahn Byung Tae,Jun Young Kwon 한국재료학회 2004 한국재료학회지 Vol.14 No.5

We investigated the growth feasibility of polycrystalline Si film on mica substrate for the transfer of the layer to a plastic substrate. The annealing temperature was limited up to $600^{\circ}C$ because of crack development in the mica substrate. Amorphous Si film was deposited on mica substrate by PECVD and was crystallized by furnace annealing. During the annealing, bubbles were formed at the Si/mica interface. The bubble formation was avoided by the Ar-plasma treatment before amorphous Si deposition. A uniform and clean polycrystalline Si film was obtained by coating $NiCl_2$ on the amorphous Si film and annealing at $500^{\circ}C$ for 10 h. The conventional Si lithography was possible on the mica substrate and the devices fabricated on the substrate could be transferred to a plastic substrate.