• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.213-219
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• 2003

As the 2-D hydraulic experimental results for the submerged rubble-mound structure, we have concerned with their stability/function characteristics of structures by the effects of wave force, scour/deposition at the toe and wave transmission ratio at the lee-side sea. And as to investigate the variation characteristics of wave transmission ratio which depended to a geometrical structure of the submerged breakwater profiles, the critical conditions for the depth of submergence and crest width obviously presented. In summary, there results lead us to the conclusions that the wave control capabilities of submerged breakwaters by the variation of the submergence depth is high about 4 time degrees at the efficiency than the that of crest width. The destruction of covering block at the crest generated at the region which located between maximum damage curve, it maximum damage/failure station from the toe of the structure were 0.2L. As the wave transmission coefficient and the slope of the structure increase, the damage/failure ratio and the maximum scour depth at the toe was extended, respectively. When maximum scour depth happened. The destruction of covering block which located at the toe generated at the front slope destruction. Finally, it was found from the results that the optimization of structure may be obtained by the efficiently decision of the submergence depth and crest width in the permissible range of wave transmission ratio.

• 복식
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• 제52권5호
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• pp.31-45
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• 2002

In this paper. the focus is laid on identifying preferred wedding dress image and its co-relationship with self image of female university students. the biggest potential customer group in the industry. As for the research method. it conducted both review of literature and empirical research method. Through the former approach, four main research questions were derived : 1) What is the preferred wedding dress image of female university students\ulcorner 2) What is the relationship between real self-image and preferred wedding dress image\ulcorner and 3) that between ideal self-image and preferred wedding dress image\ulcorner 4)What is the relationship between the consistency level of the two self-images and preferred wedding dress image\ulcorner In the empirical mode of research, 404 surveys were counted in the final analysis among 450 questionnaires completed by female undergraduate students in Seoul and Chun-an city. Collected data analyzed using factor analysis. frequency analysis. descriptive analysis. scheffe test. multiple-regression analysis and t-test. Results are as follows: first, the sophisticated image was most preferred among female students, followed by elegant splendor. lovable and chaste, feminine and decorative, and characteristic and sexy image. This result indicates how wedding dress trend has a keen sensibility to general fashion trend just like the trend of outfits for everyday life. Secondly, the research results indicated consistent level of co-relationship among the real and ideal self-image and the preference of wedding dress image. And the last the level of consistence between the ideal self-image and the real self-image directly related to the preference level of wedding dress image, showing almost no significance.

• 한국자동차공학회논문집
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• 제6권2호
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• pp.12-20
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• 1998

Exter ballistics of a typical high-speed projectile is studied through a flow-visualization experiment and an unstructured grid Navier-Srokes computation. Experiment produced a schlieren photograph that adequately shows the characteristic features of this complex flow, namely two kinds of oblique cone shocks and turbulent wake developing into the downstream. A hybrid scheme of finite volume-element method is used to simulate the compressible Reynolds-Averaged Navier-Stok- es solution on unstructured grids. Osher's approximate Riemann solver is used to discretize the cinvection term. Higher-order spatial accuracy is obtained by MUSCL extension and van Albada ty- pe flux limiter is used to stabilize the numerical oscillation near the solution discontinuity. Accurate Gakerkin method is used to discretize the viscous term. Explict fourth-order Runge-Kutta method is used for the time-stepping, which simplifies the application of MUSCL extension. A two-layer k-$\varepsilon$ turbulence model is used to simulate the turbulent wakes accurately. Axisymmetric folw and two-dimensional flow with an angle of attack have been computed. Grid-dependency is also checked by carrying out the computation with doubled meshes. 2-D calculation shows that effect of angle of attack on the flow field is negligible. Axi-symmetric results of the computation agrees well with the flow visualization. Primary oblique shock is represented within 2-3 meshes in numerical results, and the varicose mode of the vortex shedding is clearly captured in the turbulent wake region.

• Journal of Preventive Medicine and Public Health
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• 제41권2호
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• pp.107-114
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• 2008

Objectives : The aim of this study is to investigate the association between obesity indices(body mass index, weight, waist-hip ratio and waist circumference) in adolescents and the carotid intima-media thickness (C-IMT) in early adulthood. We also wanted to identify the best predictor for C-IMT among these obesity indices. Methods : This study used community-based prospective cohort study, known as the Kangwha Study, and the data we used were from subjects who were 16-years old in 1996 (defined as "adolescence") and 25 years-old in 2005 (defined as "early adulthood"). The 256 subjects (113 men and 143 women) who were used for analysis participated in both follow-ups, and they underwent B-mode ultrasonography of the carotid arteries at the early adulthood follow-up. Obesity indices were defined as the body mass index, weight, waist-hip ratio and waist circumference. The C-IMT was defined as the mean of the maximal IMT of each common carotid artery. The C-IMT and obesity indices associations were evaluated via multivariable regression, logistic regression and the receiver-operator characteristic curve analyses. Results : In men, all the obesity indices in adolescence were showed to have statistically significant positive association with C-IMT in early adulthood. However, no such relationship was showed in women. On multiple regression and logistic regression analysis, the waist-hip ratio showed the biggest relationship with the C-IMT among the 4 obesity indices. However, there were no statistical significant differences and no best predictor was found. For the women, the obesity incidences and C-IMT showed no relationships. Conclusions : This study suggested that obesity in adolescence was related to an increase C-IMT in healthy young Korean men.

• 한국소음진동공학회논문집
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• 제25권12호
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• pp.830-842
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• 2015

This paper aims to develop a SI(structural identification) technique using the kinetic energy optimization technique(KEOT) and the direct matrix updating method(DMUM) to decide on optimal location of sensors and to update FE model respectively, which ultimately contributes to a composition of more effective SHM. Owing to the characteristic structural flexing behavior of cable bridges, which makes them vulnerable to any vibration, systematic and continuous structural health monitoring (SHM) is pivotal for them. Since it is necessary to select optimal measurement locations with the fewest possible measurements and also to accurately assess the structural state of a bridge for the development of an effective SHM, a SI technique is as much important to accurately determine the modal parameters of the current structure based on the data optimally obtained. In this study, the KEOT was utilized to determine the optimal measurement locations, while the DMUM was utilized for FE model updating. As a result of experiment, the required number of measurement locations derived from KEOT based on the target mode was reduced by approximately 80 % compared to the initial number of measurement locations. Moreover, compared to the eigenvalue of the modal experiment, an improved FE model with a margin of error of less than 1 % was derived from DMUM. Finally, the SI technique for long-span bridges proposed in this study, which utilizes both KEOT and DMUM, is proven effective in minimizing the number of sensors while accurately determining the structural dynamic characteristics.

• 대한교통학회지
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• 제24권3호
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• pp.197-205
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• 2006

본 연구에서는 복합대중교통체계 하에서 환승을 명확하게 반영하면서 신교통수단의 수요를 분석할 수 있는 분석기법을 제안하였다. 제안된 분석방법은 통행특성별로 그룹을 나누어 각 그룹별로 별도의 적합한 교통수요모형을 적용함으로써 좀 더 현실적인 교통수요분석이 가능하도록 하였다. 구체적으로 신교통수단만 이용하는 통행수요(신교통수단 노선구간 내 통행), 신교통수단을 이용하여 출발하거나 도착하는 통행수요(신교통수단 노선구간 내-외부 통행), 신교통수단의 노선을 통과하는 통행수요(신교통수단 노선구간 통과 통행)로 구분하여 통행의 특성별로 적합한 교통수요분석방법을 별도로 적용할 것을 제안하였다. 또한 본 연구에서는 신교통수단 정책과 같이 승용차에서 대중교통으로의 수단 전환이 가능한 정책 분석에서 사업 시행시와 사업 미시행시 간의 수단별 O/D 값에 차이가 있을 때에도 동일한 지표에 의해 일관된 정책평가 결과를 제시할 수 있는 통행시간 편익산출 방법도 제안하였다.

• Journal of Welding and Joining
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• 제33권2호
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• pp.69-77
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• 2015

High strength steels have been continually being developed to improve in fuel economy in automotive and ensure safety of passengers. New bonding and welding methods have been required for improving weldability on high strength steels. In this study, resistance spot welding and Weld-bond with nugget diameters of 4.0mm, 5.0mm, 6.0mm and 7.0mm were produced and tested, respectively. In order to confirm the effect of nugget diameters on tensile shear characteristic of the Weld-bond, tensile shear characteristics of Weld-bond were compared with those of resistance spot welding and adhesive bonding. Peak load of Weld-bond were increased as the nugget diameter increases. After appearing maximum peak load continuous fracture followed with second peak owing to load being carried by resistance spot weldment. Fracture modes of the adhesive layer in Weld-bond fractures were represented by mixed fracture mode, which are cohesive failure on adhesive part and button failure at resistance spot welds. The results showed that the tensile shear properties can be improved by applying Weld-bond on TRIP steel, and more apparent with nugget diameter higher than 5${\surd}$t.

• 한국멀티미디어학회논문지
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• 제13권4호
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• pp.575-581
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• 2010

트리밍 미디어와 압축 기술의 발전과 인터넷 사용의 확대로 디지털 음악, 비디오, 영상은 인터넷을 이용하여 사용자에게 순간적으로 배포되어질 수 있다. 하지만, 대부분 기존의 디지털 저작권의 관리는 안전하지 못하고 실시간적인 멀티미디어 응용에 의해 야기되는 데이터의 방대한 양의 처리를 빠르게 수행하지 못한다. Scalable video codec (SVC) 은 변화하는 네트워크 대역과 다양한 어플리케이션 목적에 적응 가능한 Spatial, Temporal, SNR 스케일러빌러티를 제공한다. 한편, 많은 멀티미디어 서비스에서 보안성은 인증받지 않은 사용자의 컨텐츠 접근과 분배를 제한하는 중요한 요소이다. 따라서 MPEG4-SVC에 적합한 새로운 암호화 시스템의 구현은 반드시 필요하다. 본 논문에서는 MPEG4-SVC의 스케일러빌러티 특성을 그대로 유지시켜주는 스케일러블 암호화 기술을 제안한다. 기본 레이어에는 선택적 암호화 기법을 적용하여 암호화하고 확장 레이어에는 다양한 Motion Vector Scrambling(MVS)과 인트라 모드 암호화 방법을 적용하였다. 복호화 단계에서는 각 암호화된 레이어마다 다른 암호화 키로 접근이 가능하다. 실험 결과에서 제안된 기술은 암호화 속도가 빠르고 에러에 강한 특성과 추가되는 비트스트림의 크기가 아주 적은 장점이 있다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.134-139
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• 2002

Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear power plant. However, effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. Acoustic emission(AE) has been widely used in various fields because of its extreme sensitivity, dynamic detection ability and location of growing defects. In this study, we investigated failure modes of locally wall thinned pipes and AE signals by bending test. From test results, we could be divided four types of failure modes of ovalization, crack initiation after ovalization, local buckling and crack initiation after local buckling. And fracture behaviors such as elastic region, yielding range, plastic deformation range and crack progress could be evaluated by AE counts, accumulative counts and time-frequency analysis during bending test. It is expected to be basic data that can protect a risk according to local wall thinning of pipes, as a real time test of AE.

• 한국전자통신학회논문지
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• 제8권6호
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• pp.941-947
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• 2013

본 연구는 노인들의 직업 활동과 삶의 질과의 관련성을 규명하여 노인일자리 프로그램에 기초자료를 제공하고자 국민건강영양조사 자료를 사용하여 수행하였다. 조사대상은 65세 이상 인구 1,472명을 대상으로 하였다. 조사방법은 t-test, ANOVA 그리고 다단계회귀분석을 사용하였다. 연구결과 직업을 가진 노인들의 삶의 질이 직업이 없는 노인들에 비해 삶의 질이 높게 나타났다(${\beta}=0.041$, p=0.000). 특히, 근로형태에서는 상용직이 평균0.93점(p=0.005), 근로시간은 전일제가 평균 0.91점(p=0.079), 직업분류에서는 전문직이 평균0.96(p=0.044)점으로 삶의 질이 높았다. 노인일자리 사업에서 연구결과를 고려하여 일자리사업을 수행하여 노인들의 삶의 질을 높일 필요가 있다고 생각한다.