• 환경영향평가
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• 제31권5호
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• pp.334-342
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• 2022

대기환경보전법이 강화되면서 야외저탄장을 옥내화 함으로써 외부로 날리는 비산먼지는 감소했지만, 저탄장에서 발생하는 석탄 비산먼지와 유해물질들을 단순히 격리함으로서 이러한 물질들이 내부에 축적되어 또 다른 문제를 야기할 수 있다. 본 연구는 이를 해결하기 위해 운영 중인 옥내 저탄장을 선정하여 내부 기류 흐름 양상과 환기량을 분석하였다. 옥내저탄장 내부 기류는 전반적으로 지형적으로 산 쪽에 접한 남서쪽으로 이동하는 경향을 보였다. 그리고 바다와 접한 북쪽 루버에서는 해풍에 의한 기류가 유입되고 있었다. 옥내저탄장 내부로 유입되는 총 유량은 918,691m³/h, 시간당 자연환기 횟수는 0.6회로 나타났다. 연구 결과를 바탕으로 내부 기류가 집중되는 위치에 강제 환기장치를 설치하는 것을 제안한다.

• 한국농촌건축학회논문집
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• 제15권4호
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• pp.95-102
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• 2013

Recently (2010), South Korea's aging rate is 11%. and expected to be 32.3% in 2040, and Japan's aging rate in 2010 is 23%, and in 2040 is expected to be 34.5%. As aging progresses, it is increasing with the elderly person with dementia. However, elderly welfare facilities are insufficient. To take care stability of elderly people with mental and physical disabilities, we need to prepare a lot of welfare facilities for the elderly. Whenever physical conditions and service needs change of the disability elderly, Elderly are forced to move to the other facility. They move from familiar places, beloved local base to unfamiliar places. They are under a lot of stress in order to adapt to new environment. This research is to check out the possibility of the systems and the effectiveness of various services and the flexibility of management in Japan. Takurosyo is responsible for a variety function of elderly medical welfare facilities. Within a short time, our country, has entered into a super-aged society, elderly health and welfare facilities are needed. However, because it requires enormous financial, it is difficult to build a new building in reality, However, if remodeling existing buildings, We can build many low-cost small-scale multi-functional welfare facilities such as the takurosyo. Such that facility would be available to us.

• 노동경제논집
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• 제28권1호
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• pp.105-133
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• 2005

우리나라에서는 대기업을 중심으로 한 노조기업과 대다수 비노조기업 간의 경제적 간극이 매우 크고 그것이 근래에 더욱 확대되었다는 인식이 퍼져있는데, 본 연구는 그 같은 인식이 실제로 경제적인 근거를 갖고 있는지를 검증하고자 하였다. 사업체에 노동조합이 존재하는가의 여부에 따른 임금격차로 측정한 노조의 임금프리미엄은 1990년대에 들어 안정적인 수준을 유지하고 있었으나 외환위기 이후 급증한 것으로 나타난다. 또한 비노조 부문과 비교해서 노조 부문에서는 초과노동의 비중이 크고 근속연수가 길며 그 격차가 꾸준히 증대되어 온 반면, 신규 입직자의 비중은 낮고 상대적인 크기도 계속 감소해 왔다는 점도 확인된다. 이 같은 결과들은 노조가 강제하는 시장균형과 노동조합이 없었을 경우의 '경쟁균형' 간에 존재하는 간격이 최근에 크게 확대되어 왔음을 제시한다.

• 한국정밀공학회지
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• 제28권3호
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• pp.383-388
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• 2011

The cold hollow cathode gas ion source is under development for multi aperture focused ion beam (FIB) system. In this paper, we describe the cold hollow cathode ion source design and the general ion source performance using Ar gas. The glow discharge characteristics and the ion beam current density at various operation conditions are investigated. This ion source can generate maximum ion beam current density of approximately 120 mA/$cm^2$ at ion beam potential of 10 kV. In order to effectively transport the energetic ions generated from the ion source to the multi-aperture focused ion beam(FIB) system, the einzel lens system for ion beam focusing is designed and evaluated. The ions ejected from the ion source can be forced to move near parallel to the beam axis by adjusting the potentials of the einzel lenses.

• 대한기계학회논문집B
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• 제23권5호
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• pp.687-694
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• 1999

An experimental study was carried out in two laboratory-scale reactors to investigate the effect of heating rate on the behavior of flame front in a pulverized coal flame. Each. reactors had different heating mechanisms. For reactor A losing large heat through transparent quartz wall. pulverized coal particles were ignited by secondary air of 1050K. Flame front could be visualized through the transparent wall. Reactor B was insulated with castable refractory to minimize the heat loss through the reactor wall and accompanied with secondary air of 573K. Flame front was estimated from the gas temperature and species concentration measured using R-type thermocouple(Pt-Pt/Rh 13%) and gas chromatograph at various coal-air ratios and swirl intensities. The flame front position was closely related with the magnitude of heating rate. The heating rate for lifted flame was of the order of $10^4$ to $10^5K/s$ and for coal Ignition at least over $10^4K/s$. The heating mechanism had little impact on the extinction limits. The weak swirl number of 0.68 forced the flame front to move toward the upstream by the rapid mixing of coal and air. The primary/secondary momentum ratio was an inappropriate variable to distinct the liftoff of flame.

• Journal of Biosystems Engineering
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• 제28권1호
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• pp.35-44
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• 2003

This study was conducted to develop proper model for cold storage facility that could of for uniform heat movement and air movement f3r green grocery and improve improper design of the existing container-type cold storage facility. For that reason, new model(dome-type) cold storage facility was developed using 3-D CFD(computational fluid dynamics) simulation. The size was 6m${\times}$6m${\times}$5m. Its size and configuration were same to simulation model. Unit cooler was designed to send cold air in 4 side ways. A dome-type cold storage facility showed uniform distributions of air temperature and velocity because cold air was forced to move down along the ceiling and the wall and then circulated to the unit cooler from the central part of the floor. Dome-type cold storage facility also showed by low wind velocity, below 1 m/s that could minimized cold damage and quality deterioration.

• 한국수학교육학회지시리즈A:수학교육
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• 제52권2호
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• pp.203-215
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• 2013

We explored implications of storytelling in learning and teaching mathematics and examined examples of storytelling for deep understanding of the educational meanings of storytelling and new direction of storytelling approach to mathematics teachers. Mathematics had been commonly considered as the subject irrelevant to the narrative mode of thinking and only relevant to the paradigmatic mode of thinking that has rigorous logical forms and independent from human mind. As a result, this common sense forced a transmission pedagogy of mathematics: only the teachers as owners of the objective and logical truth of mathematics could transmit mathematical truths to students. Storytelling is highlighted as an alternative to the common teaching practices of mathematics focused only on the paradigmatic mode of thinking. Although a lot of research about the educational uses of storytelling mainly focused on the development and modification of stories, we suggested that the educational interest about storytelling should move to the elements or techniques for the positive effect of storytelling.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.867-872
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• 2009

In centrifugal oil filters particles are forced to move toward the filter casing wall by centrifugal force in the rotating oil flow and the particles are trapped and removed on the filter paper installed at the wall. In the present study, flow field of oil and particle motion in a centrifugal oil filter has been numerically calculated in order to estimate the filtering efficiency for various operating conditions. Fluent code was used for the numerical calculations. Uncoupling the oil flow and the particle motion and the use of particle tracking trajectory enabled the estimation of filtering efficiency for various particle sizes, particle density and the filter rotational speed. Higher filtering efficiency was observed for heavier and larger particles as well as higher filter rotational speed. For the typical case of the particle density of $6000kg/m^3$ and the particle size of $10{\mu}m$ at 3500 RPM, the calculated filtering efficiency per passage was 0.31.

• Ocean Systems Engineering
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• 제3권4호
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• pp.257-273
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• 2013

Top tensioned riser (TTR) is often used in a floating oil/gas production system deployed in deep water for oil/gas transport. This study focuses on the extension of the existing numerical code, known as CABLE3D, to allow for static and dynamic simulation of a TTR connected to a floating structure through a tensioner system or buoyancy can, and restrained by riser guides at different elevations. A tensioner system usually consists of three to six cylindrical tensioners. Although the stiffness of individual tensioner is assumed to be linear, the resultant stiffness of a tensioner system may be nonlinear. The vertical friction between a TTR and the hull at its riser guide is neglected assuming rollers are installed there. Near the water surface, a TTR is forced to move horizontally due to the motion of the upper deck of a floating structure as well as related riser guides. The extended CABLE3D is then integrated into a numerical code, known as COUPLE, for the simulation of the dynamic interaction among the hull of a floating structure, such as spar or TLP, its mooring system and riser system under the impact of wind, current and waves. To demonstrate the application of the extended CABLE3D and its integration with COUPLE, the numerical simulation is made for a truss spar under the impact of Hurricane "Ike". The mooring system of the spar consists of nine mooring lines and the riser system consists of six TTRs and two steel catenary risers (SCRs).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1536-1539
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• 1994

The influence due to metallic particle contaminated on spacer surface is remarkable in the decreasing of dielectric strength in $SF_6$ GIS. In relation with this problem, We studied, AC flash-over voltage characteristics and breakdown mechanism are investigated under metallic particle initiated condition in $SF_6$ gas by varying the particle position, particle shape with a plane-plane electrode. The main results arc as follows 1. The small amount of the metallic particle in the gap do not make flash-over voltage to be influence, but the significant decrease of th flash-overed voltage is result in case of the big and long size of the metallic paraticle. 2. Influence of the flash-over voltage are lowest in the mid and are highest in the electrode of metallic particle position. 3. In case of the initiated metallie particle, The more the pressure are high, the more the recluced ratio of flash-over voltage are high. 4. The metallic particle shape which results in the reduced flash-over voltage forced the critical pressure to move in to the region of low pressure. 5. The existance of the metallic particle on the upper electrode side and high pressure make the decreasing ratio of flash-over voltage bigger than that of the ground side electrode.