• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1998.09a
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• pp.20-23
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• 1998

현재 해운대 해빈의 사빈이 유실되고 있지만, 이에 대한 연구는 미흡한 상태에 있다. 또한 현장 관측자료의 결핍으로 해운대 해빈 부근의 해수순환패턴과 표사이동을 포함한 해빈변형기작의 규명이 곤란하다. 따라서 해안선 부근의 파랑을 관측하여 실제 현장에서의 연안류 및 연근해 해수순환계의 존재를 밝히고, 그와 관련하여 해안선 부근의 표사이동 양상을 밝히고자 한다. 해운데 해빈에서 파랑의 물입자 운동을 관측하기 위하여 3, 5, 8, 10월에 11, 8, 7, 12개의 정점을 정하여 유속을 측정하였다. (중략)

• Nuclear Engineering and Technology
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• v.1 no.2
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• pp.103-106
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• 1969

A new representation for the Dirac equation, which may be appropriate to describe the interaction of the charged particle with the electric field, is derived by introducing a gauge-independent unitary transformation. It is shown that in this representation the effective Hamiltonian without potentials has a new feature in the non-relativistic limit.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1322-1328
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• 2005

The circulation flows passing through the Ekman boundary layer on the rotating disk and transfer the angular momentum into the interior region of the container. Consequently, the circulation enhances the momentum transfer and the interior fluid is divided by a propagating shear front. This investigation focuses on computer vision and image processing technique for analysis of Non-Newtonian Fluids. To visualize marching velocity shear front for the transient flow, a particular shaped particles and light are used. To validate the proposed method, quantitative image are compared with the optical data acquired by a direct measurement of LDV (Laser Doppler Velocimetry).

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.190-204
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• 2010

This study firstly examined the socioeconomic and health factors associated with infiltration of private health insurance. Secondly, we compared health behavior, outpatient and inpatient use of private health insured with uninsured. The method of this study is that secondary analysis of the 2008 Korea National Health and Nutrition Survey was conducted for 7178 respondents aged 19 over. We use the logistic regression and t-test for data analysis. The first dependent variable was dichotomy which is divided to private health insured or uninsured and the second dependent variable was the presence and frequency of outpatient and inpatient use. The descriptive variables was gender, age, marital status, income, education, occupation, type of national health insurance, residential area, self confidence of health, prevalence rate of common disease, activity limitation, drinking and smoking status. The result of the major findings are as follows. First, 59 under aged person, married person, people in the higher brackets of income, national employee insured were more likely to infiltrate private health insurance. The poor self confidence of health, activity limitation, person with hypertension or allergic rhinitis and smoker were negatively related in infiltrating private health insurance. Second, private health insured did more preventive behavior such as self-paid health examination, cancer screening, regular exercise than uninsured. Third, private health insured was positively related with the presence of outpatient use and frequency of inpatient use

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.5
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• pp.512-517
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• 2014

This paper describes the development of new sweeping machine based on Cyclone Technology, which maintains constant suction power and uses it in a industrial applications as a method for dust removed from grinding work. The performance of a cyclone separator is determined by the turbulence characteristics and particle-particle interaction. To achieve this goal, we design cyclone technology based dust separator for sweeping machine has been proposed as a system which is suitable to work utilizing dust suction alternative to conventional manual system. and Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the working fluid that flow into cyclone dust separator in order to design optimal structure of the sweeping machine. The validation of cyclone model with CFD is carried out by comparing with experimental results.

• Journal of the Korean Institute of Gas
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• v.13 no.5
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• pp.7-14
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• 2009

This study describes to analyze the pressure drop characteristics for the air-particle flow in pneumatic coal powder conveying system and to proper design of the orifice located in the system to enhance combustion efficiency in furnace of the coal-fired power plant. Usually the system consists of the straight type pipe, the curved type pipe and the elbow, which cause increase of the pressure drop. In this study, the pressure drop arised in the system with straight and curved type pipes is analyzed with interactions of motion of air flow and particles. It is realized that total pressure drop increases with increasing of the pipe length and the angle of curved type pipe due to friction loss of air and particles in the system. The program for analysis of the pressure drop and optimum design of the orifice size for air flow control in the system is developed. The result is also compared with the existing system.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.95-95
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• 2022

남극에 상주하는 여러 과학기지 근처 해역에서 5 mm 이하의 크기를 가지는 미세플라스틱이 다량 발견되고 있으며, 그에 따라 과학기지에서 방출하는 방류수가 미세플라스틱의 지역 소스로 여겨지고 있다. 현재는 미세플라스틱의 오염 수준을 이해하는 정도에서 그쳤으며, 미세플라스틱의 물리적인 운송 메커니즘을 이해하고자 하는 시도는 상대적으로 부족한 실정이다. 남극 세종과학기지 근처에서도 미세플라스틱이 발견됨에 따라 본 연구에서는 과학기지 인근인 마리안 소만(Marian Cove)에서의 미세플라스틱 운송 메커니즘을 확인하고자 한다. 연구 대상 지역에서 미세플라스틱의 체류 시간은 짧기 때문에, 미세플라스틱에 생물오손 또는 풍화작용이 일어나기에는 충분하지 않은 시간이다. 따라서, 마리안 소만에서 발견된 미세플라스틱에 대해 연직 속도에 따라 확실히 가라앉는 그룹과 확실히 떠오르는 그룹으로 나누어 입자의 이송 메커니즘을 파악하였다. 해수 유동 모델과 파랑 모델을 결합하여 마리안 소만의 해수 흐름을 재현하였으며, 과학기지 방류 구 위치에서 방출된 미세플라스틱의 이송 경로는 라그랑지안 입자 추적(Lagrangian Particle Tracking) 방법을 이용하였다. 본 연구에서는 미세플라스틱의 궤적을 설명하기 위해 입자의 이송에 영향을 주는 힘을 결정할 수 있는 무차원 수 HK angle을 제안하였으며, 이를 이용하여 마리안 소만에서의 미세플라스틱 이송을 설명하였다. 대상 해역 내에서 확실히 떠오르는 그룹은 표층 흐름을 따라 해안선에 도달하였으며, 확실히 가라앉는 그룹은 방출 직후 빠르게 가라 앉으며 방출 위치 근처인 해저에 집적되었다. HK angle에 따르면, 마리안 소만의 연직 흐름이 강할 경우에는 미세플라스틱의 특성에 관계없이 해수 흐름을 따라 이송됨을 확인하였다. 더 나아가, 조석에 따라 미세플라스틱의 방출 시간을 달리하고, 방출 위치를 달리하여 모의함으로써 마리안 소만과 같이 작은 만에서 미세플라스틱 오염도를 줄이기 위한 적절한 방류수 방출 시간 및 위치를 제안하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.4
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• pp.352-359
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• 2012

An experiment was carried out to figure out the turbulence flow characteristics in the wake of the transom stern's 2-dimensional section by 2-frame grey level cross correlation PIV method at Re= $3.5{\times}10^3$, Re= $7.0{\times}10^3$. The angles of transom stern are $45^{\circ}$(Model "A"), $90^{\circ}$(Model "B") and $135^{\circ}$(Model "C") respectively. The depth of wetted surface is 40mm from free surface. Strong turbulence intensity appears at the interaction between the flow separation of the bottom of a model and the free surface. This study provides statistic flow information such as turbulence intensity, Reynolds stress and turbulence kinetic energy. Model C type (Raked transom) has low Reynolds stress and turbulence kinetic energy.

• Journal of the Korean Chemical Society
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• v.47 no.3
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• pp.265-272
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• 2003

This study investigated the types of analogies that 7th graders generated to explain three states of matter, the difference of analogies by achievement level, and the misconceptions that might be induced from the analogies. The results revealed that many students made the enriched and storytelling analogies with concrete materials or events from their everyday experiences. However, they made analogies without considering causal relationship such as the change of particular arrangement based on latent heat or molecular movement. The students of high achievement level considered the arrangement and the movement of molecules and made the enriched and storytelling analogies more than the students of low achievement level. The students made the analogies that might induce misconceptions such that the molecules don't move in solid state or the particles could be changed according to the states.

• Resources Recycling
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• v.31 no.6
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• pp.36-43
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• 2022

The general screen used to separate the particle size of recycled aggregate has restrictions when dealing with moisturized materials because of the blockage phenomenon. Therefore, in this study, to improve the separation efficiency of the conventional screen, the excellence of additional vibrating device based on spring was decided by a simulation experiment based on the discrete element method (DEM). The motion characteristic was investigated by analyzing the displacement, amplitude, and strain angle based on the spring design. Further, the particle motion was simulated by applying spring motion. The material flow and separation efficiency of the screen applied spring were confirmed as 9.2 kg/s and 97 %, respectively. Consequently, the improvement in the screen applied with blockage prevention spring was confirmed by comparing with the conventional screen.