• 한국방재안전학회논문집
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• 제12권2호
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• pp.47-56
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• 2019

주차장 화재 시 다량의 연기 발생으로 소방대원이 화점에 진입하기 곤란한 문제점을 극복하고자 최근 주차장 환기 목적으로 설치된 급 배기팬과 유인팬(Jet fan)을 이용하여 연기를 배출하는 방법을 이용하고 있다. 본 연구에서는 급배기팬만 동작하는 조건과 유인팬이 함께 동작하는 2가지 조건에서 연기층의 유동변화를 CCTV를 이용하여 관찰하였으며, 또한 hot smoke test가 주차장 환기 성능평가 방법으로서의 적정성을 평가하기 위해 플럼 주위의 온도를 Alpert eq.과 비교 분석하였다. 그 결과 jet fan을 동시에 동작시키는 경우 연기층이 교란될 수 있음을 확인할 수 있었으며, 그로인하여 초기 피난 장애 우려가 있을 것을 것으로 분석되었다. 다만, jet fan이 추가로 작동됨에 따라 배기성능은 향상되는 것을 관찰용 CCTV로 확인할 수 있었으며, 이는 진압전술을 펴는데 도움이 될 것으로 판단된다. 플럼 주변의 온도를 측정하여 Alpert eq과 비교한 결과 Plume 중심축에서 약 $2^{\circ}C$ 낮고 연기가 배출되는 방향으로 8 m에서는 $9.0^{\circ}C$ 높은 것으로 분석되었다. Plume 주변의 온도 측정 결과는 AS 4391-1999의 예상 최대 온도보다 낮았고 실험으로 인한 예상 온도 위험을 초과하지 않았다. 이 결과와 같이 고온 연기 시험의 진행으로 인한 온도 위험성이 예측 가능하기 때문에 관련 기준이 없는 주차장의 연기 제어 성능 평가를 위한 일반적인 평가 방법 중 하나로 활용 가능할 것이다.

• 대기
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• 제27권3호
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• pp.317-329
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• 2017

Ocean mixed layer (OML) depth affects diurnal cycle of sea surface temperature (SST) induced by change of solar radiation absorption and heat budget in ocean. The diurnal SST variation can lead to convection over the ocean, which can impact on localized precipitation both over coastal and inland. In this study, we investigate the OML characteristics affecting the diurnal cycle of SST for the Korean Peninsula and surrounding areas. To analyze OML characteristics, HYCOM oceanic mixed layer depth (MLD) and wind field at 10 m from ERA-interim during 2008~2016 are used. In the winter, MLD is deeply formed when the strong wind field is located on perpendicular to continental slope over deep seafloor areas. Besides, cooling SST-induced vertical mixing in OML is reinforced by dry cold air originated from Siberia. The OML in summer is shallowly distributed about 20 m. In order to estimate the impact of OML model in high resolution NWP model, four experimental simulations are performed. At this time, the prognostic scheme of skin SST is applied in NWP to simulate diurnal SST. The simulation results show that CNTL (off-OML) overestimates diurnal cycle of SST, while EXPs (on-OML) indicate similar results to observations. The prediction performance for precipitation of EXPs shows improvement compared with CNTL over coastal as well as inland. This results suggest that the application of the OML model in summer season can contribute to improving the prediction for performance of SST and precipitation over coastal area and inland.

• 한국세라믹학회지
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• 제47권1호
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• pp.26-38
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• 2010

Degradation in Solid Oxide Fuel Cell performance can be ascribed to the following fundamental processes from the materials chemical point of view; that is, diffusion in solids and reaction with gaseous impurities. For SOFC materials, diffusion in solids is usually slow in operation temperatures $800\sim1000^{\circ}C$. Even at $800^{\circ}C$, however, a few processes are rapid enough to lead to some degradations; namely, Sr diffusion in doped ceria, cation diffusion in cathode materials, diffusion related with metal corrosion, and sintering of nickel anodes. For gaseous impurities, chromium containing vapors are important to know how the chemical stability of cathode materials is related with degradation of performance. For LSM as the most stable cathode among the perovskite-type cathodes, electrochemical reduction reaction of $CrO_3$(g) at the electrochemically active sites is crucial, whereas the rest of the cathodes have the $SrCrO_4$ formation at the point where cathodes meet with the gases, leading to rather complicated processes to the degradations, depending on the amount and distribution of reacted Cr component. These features can be easily generalized to other impurities in air or to the reaction of nickel anodes with gaseous impurities in anode atmosphere.

• 산업경영시스템학회지
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• 제39권2호
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• pp.103-112
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• 2016

As supply chains are globalized, multinational companies are trying to optimize distribution networks using a hub and spoke structure. In this hub and spoke network structure, multinational companies locate regional distribution centers at hub airports, which serve demands in their corresponding regions. Especially when customers put higher priority on the service lead-time, hinterlands of international hub airports become ideal candidate locations for the regional hub distribution centers. By utilizing excellent airport and logistics services from hub airports, regional distribution centers in the hub airports can match supply with demand efficiently. In addition, regional hub distribution centers may increase air cargo volume of each airport, which is helpful in the current extremely competitive airport industry. In this paper, we classified locational preferences into three primary categories including demand, service and risk and applied the analytic hierarchy process methodology to prioritize factors of locational preferences. Primary preference factors include secondary factors. Demand factor contains access to current and prospect markets. Service factor comprises airport and logistics perspectives. Service factor in terms of airport operations includes secondary factors such as airport service and connectivity. Service factor in terms of logistics operations contains infrastructure and logistics operations efficiency. Risk factor consists of country and business risks. We also evaluated competitiveness of Asian hub airports in terms of candidate location for regional hub distribution centers. The candidate hub airports include Singapore, Hong Kong, Shanghai, Narita and Incheon. Based on the analytic hierarchy process analysis, we derived strategic implications for hub airports to attract multinational companies' regional hub distribution centers.

• The Journal of Korean Physical Therapy
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• 제17권3호
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• pp.297-310
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• 2005

Open kinetic chain exercise has lost favour in rehabilitation after cruciate ligament reconstruction due to concerns that this exercise is harmful to the graft and will be less effective in improving function. Therefore rehabilitation has focused over the past decade on closed kinetic chain exercise. Open kinetic chain and closed kinetic chain exercises were compared for their effects on proprioception, muscle strength and knee instability in the early period of cruciate ligament reconstruction rehabilitation. The study subjects were 14 patients in 28weeks from cruciate reconstruction surgery(11 male, 3 female; mean age = 44.36 years). Closed kinetic chain exercise group used ball, balance pad and air cushion, to perform weightbearing exercises and the open kinetic chain exercise group used elastic rope and N-K table, to perform non-weightbearing exercises. Between tests, subjects trained 5 times per week for 2 weeks. Statistical analysis was by Wilcoxon signed rank test and Mann Whitney U test. In result, this study shows that both open and closed kinetic chain exercise programs lead to an improved muscle strength and Lysholm score. But there was no improvement in proprioception at both exercises. Closed versus open kinetic chain exercise in early period of rehabilitation after cruciate ligament reconstruction surgery do not differ in their effects on knee proprioception, muscle strength and instability. But the effect of closed kinetic chain exercises was showed more improvement than open kinetic chain exercises between pre-post exercises. Therefore further study is required to assess effect of both groups in more long period.

• 대한방사선치료학회지
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• 제19권2호
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• pp.99-106
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• 2007

목 적: 방사선치료 중 환자의 자세나 해부학적 구조상 장기의 움직임과 치료 시 환자를 조준하면서 치료부위의 변화가 다양하게 발생할 수 있다. 이와 같은 요인은 종양부위나 정상조직에 대한 선량분포에 영향을 미치게 된다. 이는 치료계획용전산 화장비에 의해 계산된 선량이 실제임상 치료 시 서로 다른 선량이 조사될 수 있다. 인체의 생리학적인 움직임과 장기 내의 움직임 등은 고정기구나 정확한 환자의 치료준비에 의해서 치료조준의 정확성을 높일 수 있다. 본 연구의 목적은 토모영상을 통해 육안적종양체적(Gross tumor volume, GTV)과 장기의 치료 간에 발생하는 차이점을 평가하고자 한다. 대상 및 방법: 본원환자로서 직장풍선을 이용하여 치료하는 전립선암 환자 3명을 대상으로 하였고, 3달 동안 영상 자료를 수집 하였다. 각 환자마다 치료횟수 26회에 대한 토모영상을 획득하였고, 총 76회의 토모영상을 수집하였다. 각각의 토모영상은 전산화단층촬영모의치료(Computed tomography simulation, CT-simulation) 시의 중심점을 이용하였고, 매 치료 시 직장풍선에 60 cc의 공기주입 후 항문 가장자리에서 6 cm 깊이에 고정하여 전립선의 움직임을 고정시킨 후 치료 전에 토모영상을 획득하였다. 토모영상은 5 mm 두께로 영상을 획득하였다. 본 연구의 분석방법으로 CT-simulation와 MVCT (Megavoltage computed tomography, MVCT)의 융합을 위하여 납 볼을 이용하여, 토모치료의 3가지 영상융합방법으로 Bone technique, bone/tissue technique, full image technique을 이용하여 치료준비(setup)의 오차를 분석하였다. 영상융합은 눈에 보이는 납 볼 기준으로 융합하고, CT-simulation 시 획득한 영상에 MVCT에서 얻어진 영상을 융합하여, 뼈와 직장풍선, GTV을 매 치료 시 각각 비교하였다. 최초 CT-simulation 시 기준점을 중심으로 평균과 표준편차는 X, Y, Z, Roll에 대하여 각각의 환자를 분석하였다. 결 과: 분석결과 각각의 방법에 위해서 직장풍선의 변화는 확연히 다르게 나타났다. 정량적으로 뼈를 이용한 영상융합 결과 X방향으로 최대 8 mm, Y방향으로 4 mm의 움직임을 보였다. 직장풍선 기준으로 영상융합 한 결과 X, Y 방향으로 6 mm, 16 mm로 분석 되었다. 한 환자의 경우 16 mm 이상의 움직임을 보였는데, 이는 직장내의 공기나 분비물에 의한 움직임으로 분석 되었다. GTV 기준분석 결과 X 방향으로 2.7$\sim$6.6 mm, 4.3$\sim$7.8 mm가 Y방향으로 움직임을 보였다. 본 연구에서 Roll에 대한 분석결과 영상융합과 분석상에서 확연한 차이점은 없었다. 분석결과 뼈 기준의 분석결과 0.37$\pm0.36^{\circ}$, GTV 기준분석 결과 0.34$\pm0.38^{\circ}$의 회전을 보였다.

• 산학경영연구
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• 제21권2호
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• pp.171-194
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• 2008

항공기내의 엔터테인먼트는 항공기를 여행의 단순공간이동 차원이 아닌 문화적 공간으로 승화시키는 결정적 요소로 작용한다. 동시에 항공사간 여행 상품 자체를 차별화 하는 도구로써 고객들의 재구매 및 구전을 가능케 하는 새로운 도구로 자리매김하고 있다. 연구에서는 기내 엔터테인먼트에 대해 살펴보고 이의 만족에 미치는 영향을 물리적 환경과 엔터테인먼트 상품 즉 콘텐츠로 구분하여 기내 엔터테인먼트 만족과 이후의 재구매와 구전에 이르는 과정을 분석하였다. 연구 결과를 요약하면 다음과 같다. 첫째, 물리적 환경에 대한 긍정적 관점은 기내 엔터테인먼트 만족에 모두 유의한 영향을 미치는 것으로 나타났다. 이중 물리적 환경의 레이아웃 즉 편의성은 물리적 환경에 있어서 가장 중요한 요인으로 나타났으며, 분위기와 디자인은 중요도가 비슷하게 나타났다. 둘째, 제공된 엔터테인먼트 콘텐츠는 기내 엔터테인먼트 만족에 유의한 정의 영향이 나타났다. 셋째, 기내 엔터테인먼트 만족은 긍정적 구전과 재구매에 모두 유의한 영향을 가지고 있다고 나타났으며, 특히 재구매보다 구전에 대한 설명력이 매우 높음을 나타내고 있다. 실증 분석을 통하여 기내 물리적 환경이 기내 엔터테인먼트에 만족에 미치는 영향을 살펴본바, 기내 엔터테인먼트도 기내라는 한정된 공간에서 제공되어지는 공간적 시간적 제약을 제외하고는 여타 엔터테인먼트 산업과 마찬가지로 다양한 물리적 환경에 의해 고객 만족이 결정되는 것을 확인할 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제29권8호
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• pp.1075-1082
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• 2016

Modern livestock production became highly intensive and large scaled to increase production efficiency. This production environment could add stressors affecting the health and growth of animals. Major stressors can include environment (air quality and temperature), nutrition, and infection. These stressors can reduce growth performance and alter immune systems at systemic and local levels including the gastrointestinal tract. Heat stress increases the permeability, oxidative stress, and inflammatory responses in the gut. Nutritional stress from fasting, antinutritional compounds, and toxins induces the leakage and destruction of the tight junction proteins in the gut. Fasting is shown to suppress pro-inflammatory cytokines, whereas deoxynivalenol increases the recruitment of intestinal pro-inflammatory cytokines and the level of lymphocytes in the gut. Pathogenic and viral infections such as Enterotoxigenic E. coli (ETEC) and porcine epidemic diarrhea virus can lead to loosening the intestinal epithelial barrier. On the other hand, supplementation of Lactobacillus or Saccharaomyces reduced infectious stress by ETEC. It was noted that major stressors altered the permeability of intestinal barriers and profiles of genes and proteins of pro-inflammatory cytokines and chemokines in mucosal system in pigs. However, it is not sufficient to fully explain the mechanism of the gut immune system in pigs under stress conditions. Correlation and interaction of gut and systemic immune system under major stressors should be better defined to overcome aforementioned obstacles.

• 대한기계학회논문집B
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• 제29권10호
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• pp.1156-1162
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• 2005

In this study, a noble method is proposed to prevent the edge overcoating (EOC) that may develop near the edge of the steel strip in the gas wiping process of continuous hot-dip galvanizing. In our past study (Trans. of the KSME (B), Vol. 27, No. 8, pp. $1105\~1113$), it was found that EOC is caused by the alternating vortices which are generated by the collision of two opposed jets in the region outside the steel strip. When the two opposed jets collide at an angle much less than $180^{o}$, non-alternating stable vortices are established symmetrically outside the steel strip, which lead to nearly uniform pressure on the strip surface. In order to deflect both jets downward by a certain angle, a cylinder with small diameter is installed tangentially to the exit of the lower lip of the two-dimensional jet. In order to find an optimum cylinder diameter, the three dimensional flow field is analysed numerically by using the commercial code, STAR-CD. And the coating thickness is calculated by using an integral analysis method to solve the boundary layer momentum equation. In order to compare the present noble method with the conventional baffle plate method to prevent the EOC, the flow field with a baffle plate is also calculated. The calculation results show that the tangentially installed cylinder at the bottom lip of the jet exit is more effective than the baffle plate to prevent EOC.

• 한국기계가공학회지
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• 제5권2호
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• pp.49-55
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• 2006

In the consideration of the problem occurred by certain return bender brazing welding works that depend only on handworks, the automatization of the whole production line is impossible due to the high dependency of skillful workers. In addition, it is difficult to establish a standardization due to the various heat exchanger model and irregular amount of orders, and the fault reduction is also impossible due to the severe difference in brazing conditions. It is necessary to develop a method, which quantitively analyzes the problem existed in this manual brazing welding of return benders and technically solves that problem, and to lead the improvement of the productivity and cost reduction in order to increase the business competitive power. Then, this will contribute the technical development of automatic welding for Korea's heat exchanger businesses. Thus, this study develops an automatic technology, which automatically controls the flame strength using digital control methods, for various models and produces a sample model. It is possible to increase the productivity and produce uniformed and qualified products by solving the problem existed in manual processes using the developed automatic return bender brazing system. In addition, the brazing condition can be automatically controlled according to the model and line speed, and such an economical operation can reduce the production cost. The developed system is expected to future applications not only heat exchangers in the field of refrigeration and air conditioning, but also other various industrial fields that apply heat exchangers, such as car and boiler industries.