• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.139-142
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• 2004

Nickel base superalloys are widely used for high temperature applications due to heat resisting capability and corrosion resistance at high temperatures. Superalloys with many strengthening alloying elements are frequently used in powder form to alleviate harmful effects of alloy segregation. HIP (hot isostatic pressing) and DB (diffusion bonding) as a form of solid-state bonding process is used to make turbine components, such as integrated turbine rotors. HIP/DB process requires many technical overcomes related to dimensional changes as well as microstructural control. In this research, HIP/DB process for nickel base superalloys, Udimet 720 and MM 247, were investigated with a view to control the dimensional change during the consolidation process. Simple disc-shaped cans were used to select the conceptual die design for the control of the dimensional change especially in radial direction. The change in the shape of consolidated shape was investigated using commercial FE code with constitutive equations fur low temperature plasticity deformation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.171-174
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• 2004

Superalloys with many strengthening alloying elements are frequently used in powder form to alleviate harmful effects of alloy segregation. HIP (hot isostatic pressing) and DB (diffusion bonding) as a form of solid-state bonding process is often used to make turbine components, such as integrated turbine rotors. HIP/DB process requires many technical overcomes related to dimensional changes as well as microstructural control. In this research, HIP/DB process for nickel base superalloys, Udimet 720, were investigated with a view to control the dimensional change during the consolidation process. Simple disc-shaped cans were used to select the conceptual die design for the control of the dimensional change especially in radial direction. The change in the shape of consolidated shape was investigated using commercial FE code with constitutive equations for low temperature plasticity and creep deformation.

• 대한교통학회지
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• 제11권2호
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• pp.27-44
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• 1993

The purpose of this study is to classify the regional structure of Pusan based on socio-economic phenomena in 1979 and 1991, and to analyze correlations between the regional structure change and traffic demend. To formalize the land-use by each zone, the Principal Component Analysis were performed by using 15 socio-sconomic variables. As a result of the analysis, five land-use factors(i.e., official, residential, commercial, manufactural, and other functions) in 1979 and four factors(i. e., residential, 3rd industrial, manufactural, and other functions) in 1991 were extracted as main regional structure components. It was proved that there is strong correlations between the regional structure change and traffic demand by using Quantification Theory II and also by testing correlation coefficient.

• Computers and Concrete
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• 제8권5호
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• pp.491-510
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• 2011

Before deciding if structures exposed to high temperature are to be repaired or demolished, their final state should be carefully examined. Destructive and non-destructive testing methods are generally applied for this purpose. Compressive strength and color change in mortars are observed as a result of the effects of high temperature. In this study, ordinary and pozzolan-added mortar samples were produced using different aggregates, and exposed to 100, 200, 300, 600, 900 and $1200^{\circ}C$. The samples were divided into two groups and cooled to room temperature in water and air separately. Compression tests were carried out on these samples, and the color change was evaluated by the Munsell Color System. The relationships between the change in compressive strength and color of mortars were determined by using a multi-layered feed-forward Neural Network model trained with the back-propagation algorithm. The results showed that providing accurate estimates of compressive strength by using the color components and ultrasonic pulse velocity design parameters were possible using the approach adopted in this study.

• 한국멀티미디어학회논문지
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• 제18권2호
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• pp.138-148
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• 2015

Object detection methods based on background learning are widely used in video surveillance. However, when a car runs with headlights on, these methods are likely to detect the car region and the area illuminated by the headlights as one connected change region. This paper describes a method of separating the car region from the area illuminated by the headlights. First, we detect change regions with a background learning method, and extract blobs, connected components in the detected change region. If a blob is larger than the maximum object size, we extract candidate object regions from the blob by clustering the intensity histogram of the frame difference between the mean of background images and an input image. Finally, we compute the similarity between the mean of background images and the input image within each candidate region and select a candidate region with weak similarity as an object region.

• 한국운동역학회지
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• 제25권2호
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• pp.157-165
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• 2015

Object : The goals of this research were to make Performance Enhanced Model(PE) taken the largest performance index (PI) through artificial variation of principle components calculated by principle component analysis for trial data, and to verify the effect through comparing kinematic factors between trial data (Raw) and PE. Method : Ten subjects (5 men, 5 women) were recruited and 80% of their maximal record was considered. The PI is a regression equation. In order to develop PE, we extracted Principle components from trial position data (by Principle Components Analysis (PCA)). Before PCA, we made 17 position data to 3 row matrix according to components. We calculated 3 eigen value (principle components) through PCA. And except Y (medial-lateral direction) component (because motion of Y component is small), principle components of X (anterior-posterior direction) and Z (vertical direction) components were changed as following. Changed principle components = principle components + principle components ${\times}$ k. After changing the each principle component, we reconstructed position data using the changed principle components and calculated performance index (PI). A Paired t-test was used to compare Raw data and Performance Enhanced Model data. The level of statistical significance was set at $p{\leq}0.05$. Result : The PI was significantly increased about 12.9kg at PE ($101.92{\pm}6.25$) when compared to the Raw data ($91.29{\pm}7.10$). It means that performance can be increased by optimizing 3D positions. The difference of kinematic factors as follows : the movement distance of the bar from start to lock out was significantly larger (about 1cm) for PE, the width of anterior-posterior bar position in full phase was significantly wider (about 1.3cm) for PE and the horizontal displacement toward the weightlifter after beginning of descent from maximal height was significantly greater (about 0.4cm) for PE. Additionally, the minimum knee angle in the 2-pull phase was significantly smaller (approximately 2.7cm) for the PE compared to that of the Raw. PE was decided at proximal position from the Raw (origin point (0,0)) of PC variation). Conclusion : PI was decided at proximal position from the Raw (origin point (0,0)) of PC variation). This means that Performance Enhanced Model was decided by similar motion to the Raw without a great change. Therefore, weightlifters could be accept Performance Enhanced Model easily, comfortably and without large stress. The Performance Enhance Model can provide training direction for athletes to improve their weightlifting records.

• 한국환경보건학회지
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• 제48권2호
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• pp.66-74
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• 2022

Background: The health effects of particulate matter (PM_2.5) bonded with various harmful chemicals differ based on their composition, so investigating and managing their concentrations and composition is vital for long-term management. As industrial complexes emit considerable quantities of pollutants, higher PM_2.5 concentrations and chemical component effects are expected than in other places. Objectives: We investigated the concentration distribution ratios of PM_2.5 chemical components to provide basic data to inform future major emissions control and PM_2.5 reduction measures in industrial complexes. Methods: We monitored five sites near the Ansan and Siheung industrial complexes from August 2020 to July 2021. Samples were collected and analyzed twice per week in spring/winter and once per week in summer/autumn according to the National Institute of Environmental Research in the Ministry of Environments' Air Pollution Monitoring Network Installation and Operation Guidelines. We investigated and compared composition ratios of 29 ions, carbon, and elemental components in PM_2.5. Results: The analysis of PM_2.5 components at the five sites revealed that ion components accounted for the greatest total mass at approximately 50% while carbon components and elemental components contributed 23~28% and 8~10%, respectively. Among the ionic components, NO₃^- occupies the greatest proportion. OC occupies the greatest proportion of the carbon components and sulphur occupies the greatest proportion of elemental components. Conclusions: This study investigated the concentration distribution ratios of PM_2.5 chemical components in industrial complexes. We believe these results provide basic chemical component concentration ratio data for establishing future air management policies and plans for the Ansan and Siheung industrial complexes.

• 한국항만경제학회지
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• 제24권4호
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• pp.47-70
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• 2008

본 연구의 목적은 확률적 생산변경함수를 이용하여 총요소생산성 성장을 도출하고 그 내부요소를 기술효율성 변화, 기술진보, 규모효율변화, 배분적 효율변화로 구분하여 생산성 성장의 요인을 파악해 보고자 함이다. 1990-2003년간 항만물류산업의 총요소생산성 증가율은 연간 0.019 (1.9%)로서 전산업의 증가율 0.010보다 높다. 그 내부의 주된 기여요인은 기술진보이고 기술효율성변화는 감소하였다. 총요소생산성의 주된 기여요인으로는 항만산업은 배분효율성, 해운산업은 기술진보, 수송장비산업은 규모효율변화를 들 수 있다. 총요소생산성 변화는 1990년대 후반이후에 감소하는 추이를 보였다. 항만물류산업은 전산업에 비하여 매우 낮은 수준의 기술효율성수준을 보여주고 있고 산출탄력성 관점에서는 1990-2003년간 자본의 탄력성(0.391)이 노동의 탄력성(0.227)보다 높지만 규모에 대한 보수는 0.618로서 최적규모에 상당히 벗어나 있다.

• 한국시뮬레이션학회논문지
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• 제15권2호
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• pp.23-29
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• 2006

본 논문은 인터넷을 통해 제공되는 VoD나 MoD 등의 멀티미디어 스트림 서비스를 위한 인터넷 스트림 서버의 사용자 요구사항을 성능 측면에서 만족시키는 방안에 대해 연구한 것이다. 본 연구의 대상인 인터넷 멀티미디어 스트림 서버는 동시에 50명의 사용자에게 화면이 끊어지지 않고 연속적으로 서비스를 제공하는 것이 목표이다. 본 논문은 이러한 요구 사항을 만족시키기 위한 설계 개념 및 동작 방식에 대해 소개하고, 설계된 멀티미디어 스트림 서버를 대상으로 성능을 시뮬레이션을 통하여 분석하며 시스템 요소 변화에 따른 성능 민감도를 분석하였다. 이는 멀티미디어 스트림 서버를 개발 하는 과정에서 시스템 성능에 큰 영향을 미치는 시스템 구성 요소를 분석하여 사용자 요구사항을 만족시키는 최적의 시스템을 설계 개발하기 위해 필요한 작업이다. 그리고, 성능 민감도 분석을 통해 사용자의 서비스 요구 패턴 변화에 대해 멀티미디어 스트림 서버가 보여주는 서비스 지연 확률을 분석하였고, PCI bus와 같은 중요 시스템 요소의 사용률도 분석하였으며, 시스템 자원을 추가로 투입할 때 나타나는 시스템 성능 변화도 분석하였다.

• 대한가정학회지
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• 제31권4호
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• pp.115-132
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• 1993

This study was designed with the purpose to analyze the factor structure of family life events and to clear the influence of related variables on family life events. The frequence of experienced events and the degree of importance of events which were the constituent components of family life events was estimated by the 650 married woman in Kangju. The results were as follows: 1. 15 factors of family life events derived by factor analysis: F.1「Expenditure and economic loss」, F.2「Growth and change of children」, F.3「Change of family structure」, F.4「Family's change」, F.5「Change of life level」, F.6「Family's social problem」, F.7「Need of care」, F.8「Family's health」, F.9「Marital relationship」, F.10「Family's social damage」, F.11「Breach with acquaintance」, F.12「Financial difficulties」F.13「Husband's problem」, F.14「Housewives' social activity」, F.15「Kinship's support」. 2. There frequence of experienced family life events such as expenditure and economic loss and breach with acquaintance was highest. 3. The degree of importance about experienced family life events such as growth and change of children was highest. 4. Age, family life cycle have significantly differenced on the degree of importance and the frequence of experienced events. 5. Education's level, family size, income, housewives' employment and family structure have differently differenced on the degree of importance and the frequence of experienced events according event factor.