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Development of four-equation turbulence model for prediction of mixed convective heat transfer on a flat plate (수평평판위 의 혼합대류 열전말 계산 을 위한 4-방정식 모델 의 개발)

  • 성형진;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.7 no.2
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    • pp.193-203
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    • 1983
  • The mixed convective heat transfer problems are characterized by the relatively significant contribution of buoyancy force to the transport processes of momentum and heat. Past analytical studies on this kind of problems have been carried out by employing either the conventional R-.epsilon. turbulence model which includes constant turbulent Prandtl number .sigma.$_{+}$ 1 or an extended R-.epsilon. turbulence model which takes account of the buoyancy effect in appropriate length scale equations. But in the latter case, the temperature variance .the+a.$^{2}$ over bar is approximated by a model under local equilibrium condition and the time scale ratio between velocity and temperature is assumed to be constant. These approximation is known to break down when the buoyancy effect is dominant. The present study is aimed at development of new computational turbulence closure level which can be applied to this rather complex turbulent process. The temperature variance is obtained directly by solving its dynamic transport equation and the time scale ratio which is variable in space is computed by a solution of a dynamic equation for the rate of scalar dissipation .epsilon.$_{\thetod}$ It was found that the computational results are in good agreement with available experimental data of wide range of unstable conditions.

A Comparative Study on Furniture Design Guidelines for the Elderly (노인주택 가구 디자인의 지침 비교)

  • Rhee, Ji-Sook
    • Korean Journal of Human Ecology
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    • v.16 no.6
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    • pp.1243-1250
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    • 2007
  • The purpose of this study was to compare government guidelines and foreign guidelines related to furniture design for elderly. Future elderly will increasingly accustomed to the provisions of improved housing, education and welfare in comparison with our forebears. Also, there will be upgrading and different need for elderly furniture in our market. The results were as follows. The height of bed was based on the height of wheelchair seat, commonly. A adjustable bed was recommended for abled and disabled elderly. A pull-down shelf, drawer, empty space under chest, folding or sliding door in wardrobe and so on were recommended as a elderly furniture. It were good adjustable sink on human scale. There were need the empty space under sink for wheelchair users, one-touch or lever faucet, etc. There have given a little furniture design guidelines for elderly in Korea until now. But those guidelines haven't been considered enough human scale of elderly including wheelchair user. Because the close investigations have not made about abled and disabled elderly for their furniture design. So first of all, the government should be examined elderly physical size more accurately for elderly furniture design. The guideline for elderly furniture design should be for abled elderly and the disabled, too.

Review of Operational Multi-Scale Environment Model with Grid Adaptivity

  • Kang, Sung-Dae
    • Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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    • v.10 no.S_1
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    • pp.23-28
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    • 2001
  • A new numerical weather prediction and dispersion model, the Operational Multi-scale Environment model with Grid Adaptivity(OMEGA) including an embedded Atmospheric Dispersion Model(ADM), is introduced as a next generation atmospheric simulation system for real-time hazard predictions, such as severe weather or the transport of hazardous release. OMEGA is based on an unstructured grid that can facilitate a continuously varying horizontal grid resolution ranging from 100 km down to 1 km and a vertical resolution from 20 -30 meters in the boundary layer to 1 km in the free atmosphere. OMEGA is also naturally scale spanning and time. In particular, the unstructured grid cells in the horizontal dimension can increase the local resolution to better capture the topography or important physical features of the atmospheric circulation and cloud dynamics. This means the OMEGA can readily adapt its grid to a stationary surface, terrain features, or dynamic features in an evolving weather pattern. While adaptive numerical techniques have yet to be extensively applied in atmospheric models, the OMEGA model is the first to exploit the adaptive nature of an unstructured gridding technique for atmospheric simulation and real-time hazard prediction. The purpose of this paper is to provide a detailed description of the OMEGA model, the OMEGA system, and a detailed comparison of OMEGA forecast results with observed data.

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A Multi-Resolution Database Model for Management of Vector Geodata in Vehicle Dynamic Route Guidance System (동적 경로안내시스템에서 벡터 지오데이터의 관리를 위한 다중 해상도 모델)

  • Joo, Yong-Jin;Park, Soo-Hong
    • Journal of Korean Society for Geospatial Information Science
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    • v.18 no.4
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    • pp.101-107
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    • 2010
  • The aim of this paper is to come up with a methodology of constructing an efficient model for multiple representations which can manage and reconcile real-time data about large-scale roads in Vector Domain. In other words, we suggested framework based on a bottom-up approach, which is allowed to integrate data from the network of the lowest level sequentially and perform automated matching in order to produce variable-scale map. Finally, we applied designed multi-LoD model to in-vehicle application.

The effects of active release technique on the gluteus medius for pain relief in persons with chronic low back pain

  • Tak, Sajin;Lee, Yongwoo;Choi, Wonjae;Lee, Gyuchang
    • Physical Therapy Rehabilitation Science
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    • v.2 no.1
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    • pp.27-30
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    • 2013
  • Objective: Low back pain is a primary of source of dysfunction and economic costs. Gluteus medius muscle co-activation and activity pattern change caused the low back pain. Active release technique (ART) is a patented, non-invasive, soft tissue treatment process that both locates and breaks down the scar tissue and adhesions. The purpose of this study was to assess the effects on chronic low back pain using ART on gluteus medius so that suggest usable treatment method for treating chronic low back pain. Design: One group pretest-posttest design. Methods: Twelve patients with chronic low back pain were participated in this study. Subjects in ART group were received 2 times a week for 3 weeks treatments with either ART on gluteus medius muscle trigger points. Outcome measures were conducted by pain intensity with a pain visual analogue scale and pressure pain threshold on gluteus medius. Results: Completion of the intervention, the visual analogue scale was decreased in ART group (p<0.05). Also pressure pain threshold was decreased in ART group (p<0.05). Conclusions: Our results suggest that the response to ART may be usable to treat low back pain. ART was presented to reduce pain level of low back in people with chronic low back pain. Further study is required to management for low back pain due to gluteus medius and more ART study.

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Development of Onboard Scales to Measure the Weight of Trucks (상용차량의 하중을 측정하기 위한 탑재형 자중계 개발)

  • Seo, Myoung Kook;Shin, Hee Yong;Lee, Ho Yeon;Ko, Jea Il;Tumenjargal, Enkhbaatar
    • Journal of Drive and Control
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    • v.18 no.1
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    • pp.9-16
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    • 2021
  • Overloaded vehicles increase the maintenance cost of road structures, and they are a major factor in causing damage to the roads and bridges. In addition, overloaded vehicles compromise the braking capability of the vehicle; thus, threatening the safety of the driver. In order to prevent overloading of vehicles, the government is cracking down on the roads by using a device that measures the weight of vehicles. But this process is inconvenient because the place where the equipment is installed is far away from where the cargo is loaded. Due to the limitations of these fixed weighing devices, there is a growing need for technology that can monitor vehicle weight distribution and overload conditions in real time. In this work, we develop an onboard scale that can measure the load (weight) of trucks in real time. The onboard scale consists of high sensors, a signal processing unit, and a display, and it measures the load using height-displacement of the vehicle's leaf spring suspension.

Effect of Side Walking Training on Balance Confidence, Falls Efficacy and Fall Risk in Acute Stroke Patients: A Randomized Controlled Pilot Study (측방보행 훈련이 급성기 뇌졸중 환자의 균형 자신감, 낙상 효능감, 낙상 위험도에 미치는 영향: 무작위 대조 예비 연구)

  • Joo, Min-Cheol;Jung, Kyeoung-Man
    • Quality Improvement in Health Care
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    • v.27 no.1
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    • pp.43-50
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    • 2021
  • Purpose: The aim of this study was to determine the effect of side walking on balance confidence, falls efficacy and fall risk in acute stroke patients. Methods: The study included 14 patients with acute stroke who were randomly allocated to a side walking group (Experimental group, N=7) and a forward walking group (Control group, N=7). Both groups performed the exercise 5 times a week for 2 weeks. Outcomes were assessed using Korean-Activities-specific Balance Confidence Scale (K-ABC), Korean-Fall Efficacy Scale (K-FES), Korean-Fullerton Advanced Balance Scale (K-FAB). Results: After 2 weeks of training, both groups showed significantly improved ABC, FES, FAB (p<.05 in both groups). However, the ABC, FES, FAB in the experimental group was significantly better than in the control group (p<.05). Conclusion: These findings indicate that side walking training may be effective at improving balance confidence and decreasing fall down risk in early stroke patients. Therefore, side walking training may be recommended as an intervention in reducing the incidence of falls in acute stroke patient.

Development of a generalized scaling law for underwater explosions using a numerical and experimental parametric study

  • Kim, Yongtae;Lee, Seunggyu;Kim, Jongchul;Ryu, Seunghwa
    • Structural Engineering and Mechanics
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    • v.77 no.3
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    • pp.305-314
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    • 2021
  • In order to reduce enormous cost of real-scale underwater explosion experiments on ships, the mechanical response of the ships have been analyzed by combining scaled-down experiments and Hopkinson's scaling law. However, the Hopkinson's scaling law is applicable only if all variables vary in an identical ratio; for example, thickness of ship, size of explosive, and distance between the explosive and the ship should vary with same ratio. Unfortunately, it is infeasible to meet such uniform scaling requirement because of environmental conditions and limitations in manufacturing scaled model systems. For the facile application of the scaling analysis, we propose a generalized scaling law that is applicable for non-uniform scaling cases in which different parts of the experiments are scaled in different ratios compared to the real-scale experiments. In order to establish such a generalized scaling law, we conducted a parametric study based on numerical simulations, and validated it with experiments and simulations. This study confirms that the initial peak value of response variables in a real-scale experiment can be predicted even when we perform a scaled experiment composed of different scaling ratios for each experimental variable.

The Research on the Cost Analysis of the Abalone Aquacultural Management in Korea (전복 양식업의 경영비 분석과 정책 시사점 연구)

  • Ock, Young-Soo
    • The Journal of Fisheries Business Administration
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    • v.46 no.2
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    • pp.13-29
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    • 2015
  • The abalone aquaculture has been very rapidly developed in Korea. Annual production quantity was less 200 tons before 2000th, it have been increased to over 9,000 tons in 2014. Also Abalone export amounts have been over 20 million dollars. The reason of rapid growth of Abalone aquaculture in Korea is due to high level profit ratio. Then now many fishing officers and other aquaculture fishers want to participate with abalone aquaculture newly. However Recent Abalone aquaculture in Korea is faced some problems. Aspects of production environmental status of fishing grounds are more aggravate, and then abalone aquaculture is exposed to various disease, and death rate of young abalone is higher. And aspect of management, the aquaculture cost is more increase. The demand of abalone also is depressing recently, this cause to come down the production price. In this viewpoint, Management analysis of abalone aquaculture in Korea is helpful for decision making of general aquaculture fisher want to participate newly. The analysis is practiced two aspects. One is index analysis, and the other is Break-even-point(BEP) analysis. The result of index analysis, average net profit rate has shown 28.0%, however the Regional difference has excessive. That is, Wando(major) has shown 39.4%, and Haenam province has shown 14.2%. On the other hand, the more scale has shown higher profit rate by aquaculture scale. And the result of BEP analysis, average has shown 93 cage number per abalone aquaculture household, and Wando(major) has shown 56 cage number, Haenam province has shown 131 cage number. The lower production abalone price of recent means higher BEP level.

Seismic performance evaluation of Precast Concrete Lining (PCL) using the 1/5 scale down model test (1/5축소 모형실험에 의한 조립식 터널라이닝 (PCL)의 내진성능 평가)

  • Lee, Yong-Jun;Chung, Hyung-Sik;Lee, Doo-Hwa;Jo, Byung-Wan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.1
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    • pp.61-70
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    • 2004
  • Precast Concrete Lining (PCL) is invented in order to resolve the problem of the cast-in-place concrete lining in Norway, However PCL could not consider the effect of earthquake because an earthquake rarely occurs in the region of Northern Europe, Consequently, the analysis of the effect of earthquake on PCL should be made before introducing PCL to Korea. The purpose of this research is to evaluate the stability of tunnel applying PCL in the case of earthquake. To evaluate the seismic performance of PCL, we used shaking table apparatus by 1/5 scale down model. The result of this research is as shows that deep tunnells satisfied for Korea seismic design criteria.

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