• Nuclear Engineering and Technology
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• 제49권5호
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• pp.979-988
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• 2017

The feasibility of cooling in a pressurized heavy water reactor after a large break loss-of-coolant accident has been analyzed using Multidimensional Analysis of Reactor Safety-KINS Standard code during the recirculation phase. Through evaluation of sensitivity of the fuel channel temperature to various effective recirculation flow areas, it is determined that proper cooling of the fuel channels in the broken loop is feasible if the effective flow area remains above approximately 70% of the nominal flow area. When the flow area is reduced by more than approximately 25% of the nominal value, however, incipience of boiling is expected, after which the thermal integrity of the fuel channel can be threatened. In addition, if a dramatic reduction of the recirculation flow occurs, excursions and frequent fluctuations of temperature in the fuel channels are likely to be unavoidable, and thus damage to the fuel channels would be anticipated. To resolve this, emergency coolant supply through the newly installed external injection path can be used as one alternative means of cooling, enabling fuel channel integrity to be maintained and permanently preventing severe accident conditions. Thus, the external injection flow required to guarantee fuel channel coolability has been estimated.

• Journal of Biosystems Engineering
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• 제30권4호
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• pp.195-201
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• 2005

The output of Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, several kinds of combined wire screen meshes were used. The results are summarized as follows; The packed meshes with high mesh no. in the side of heater part of regenerator showed effective than the packed meshes with low mesh no. in the side of cooler part of regenerator. The temperature difference and pressure drop of the regenerator were not made by the specific surface area of wire screen meshes but by the minimum free-flow area to the total frontal area. Among the No. 150 single screen meshes, 200-60 combined meshes, the 200-150-100 combined meshes showed the highest in effectiveness.

• 한방비만학회지
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• 제12권1호
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• pp.20-32
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• 2012

Object The purpose of this study is to evaluate the effect of far-infrared (FIR) therapy on weight loss. Method Thirty five participants (BMI ${\geq}25kg/m^2$) were recruited. Body weight, Waist circumference (WC), Bio Impedance Analysis (BIA), abdominal fat Computer Tomography (CT) scanning were evaluated. Results of 25 women were analyzed. Result After 6 weeks of FIR therapy, there was significant efficacy on obese women in body weight, WC, Body fat mass (BFM), and Visceral fat area (VFA). But there was no efficacy in Total fat area (TFA), and Subcutaneous fat area (SFA). Conclusion This study suggests that FIR therapy might be an effective way to promote weight and abdominal visceral fat loss in Korean obese women.

• Restorative Dentistry and Endodontics
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• 제38권2호
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• pp.59-64
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• 2013

Apical surgery cuts off the apical root and the crown-to-root ratio becomes unfavorable. Crown-to-root ratio has been applied to periodontally compromised teeth. Apical root resection is a different matter from periodontal bone loss. The purpose of this paper is to review the validity of crown-to-root ratio in the apically resected teeth. Most roots have conical shape and the root surface area of coronal part is wider than apical part of the same length. Therefore loss of alveolar bone support from apical resection is much less than its linear length.The maximum stress from mastication concentrates on the cervical area and the minimum stress was found on the apical 1/3 area. Therefore apical root resection is not so harmful as periodontal bone loss. Osteotomy for apical resection reduces longitudinal width of the buccal bone and increases the risk of endo-perio communication which leads to failure. Endodontic microsurgery is able to realize 0 degree or shallow bevel and precise length of root resection, and minimize the longitudinal width of osteotomy. The crown-to-root ratio is not valid in evaluating the prosthodontic prognosis of the apically resected teeth. Accurate execution of endodontic microsurgery to preserve the buccal bone is essential to avoid endo-perio communication.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권6호
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• pp.440-448
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• 2012

Purpose: The purpose of this study was to evaluate marginal bone loss of the alveolar crest on implants with or without guided bone regeneration and variables that have influenced. Methods: The clinical evaluation were performed for survival rate and marginal bone loss of 161 endosseous implants installed with guided bone regeneration (GBR) in 83 patients from September 2009 to October 2010 in relation to sex and age of patients, position of implant, implant system, length and diameter of implant. Study group (n=42) implant with GBR procedure, control group (n=41) implant without GBR technique. Simultaneous GBR approach using resorbable membranes combined with autogenous bone graft or freeze-dried bone allograft or combination. Radiographic examinations were conducted at healing abutment connection and latest visit. Marginal bone level was measured. Results: Mean marginal bone loss was 0.73 mm in study group, 0.63 mm in control group. Implants in maxillary anterior area (1.21 mm) were statistically significant in study group (P<0.05), maxillary posterior area (0.81 mm) in control group (P<0.05). Mean marginal bone loss 1.47 mm for implants with diameter 3.4 mm, 0.83 mm for implants of control group with diameter 4.0 mm (P<0.05). Some graft materials showed an increased marginal bone loss but no statistically significant influence of sex, implant type or length. Conclusion: According to these findings, this study demonstrated the amount of marginal bone loss around implant has maintained a relative stable during follow-up periods. We conclude that implants with GBR had similar survival rate and crestal bone level compared with implants in native bone.

• Journal of Periodontal and Implant Science
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• 제33권3호
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• pp.383-393
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• 2003

The aim of this retrospective study was to compare the amount of marginal bone loss between upper anterior area and upper posterior area with 71 upper single-tooth restorations on 2 stage machined $Br{{\aa}}nemark$ implants since Jan 1995. The second aim was to compare the bone defect group which had dehiscence and fenetration and the others in the upper anterior region. The results were as follows. 1. The most frequent reason of missing tooth in the upper anterior region was trauma by 61%. While upper posterior region showed various reasons such as congenital missing, advanced periodontitis, trauma. 2. Peri-implantitis with fistula occurred 1 of 41 implants in the upper anterior group in 1 year after loading and 2 of 32 implants in the upper posterior group failed before loading. The 1 year success rate of upper anterior group was 97.56 %, and 93.75 % for upper posterior group. 3. The mean marginal bone loss in the upper anterior group was 0.44${\pm}$0.25 mm, while 0.57${\pm}$0.32 mm in the upper posterior group. There was statistically significant difference in the amount of mean marginal bone loss (P${\pm}$0.10 mm at one year, and 0.48${\pm}$0.26 mm for the control group. No statistically significant difference of mean marginal bone loss was showen between bone defect group and the others at implantation. According to the results, the upper anterior region showed less marginal bone loss than the upper posterior region. In case of missing single upper tooth, careful consideration on recipient residual ridge to determine proper implant diameter and length, sufficient healing time, proper loading would lead to implant success. Single tooth implants in the maxilla seemed to be an alternative to fixed partial dentures without damage to adjacent teeth.

• 환경영향평가
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• 제17권4호
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• pp.243-253
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• 2008

The purpose of this study was to simulate the reduction effect of soil loss in the Yongdam reservoir watershed using SWAT model. To evaluate accuracy for flow and sediment yield of SWAT model, calibration was performed for the period from Jan. 2002 to Dec. 2003, and the verification for Jan. 2005 to Dec. 2005. The calibration and the verification were carried out using data observed at the Cheoncheon gaging station. The $R^2$ and EI values in terms of a flow were 0.8 and 0.78 respectively for calibration, whereas they for verification were 0.88 and 0.86 respectively. In terms of a sediment yield, they were 0.7 and 0.48 respectively for calibration, whereas for verification were 0.64 and 0.54 respectively. As a results from model simulation, annual mean soil loss rates in terms of forest, paddy and upland were 0.02 ton/ha/yr, 0.15 ton/ha/yr and 7.58 ton/ha/yr, respectively. The results show that the land use type of a upland has more significant impact on a total soil loss as well as a sediment yield than other types of land use. The sediment delivery ratio was determined to be about 0.35. In this study 2 land cover change scenarios for upland area were considered. These scenarios were used an input to SWAT model in order to evaluate their impact on soil loss and sediment delivery. The results show that a reduction of the upland area would reduce the soil loss and sediment yield.

• 한국안광학회지
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• 제10권4호
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• pp.329-337
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• 2005

본 연구에서는 지역에 따른 어린이들의 색각이상 유병율을 보고자 했다. 연구대상자는 4개 지역의 3-6 학년 초등학생들을 대상으로 하였다. 혈중 납과 요중 수은은 원자흡광분석기로 측정을 하였으며, 모든 연구대상자들은 CDC와 ATSDR 권고기준 이하였다. 색각검사는 Lanthony D-15 desaturated panel test를 이용하였으며, 정량적 평가와 정성적 평가를 동시에 시행하였다. 연구결과 공단지역 어린이들은 다른 지역에 비해 높은 색혼돈지수와 유병율을 보였다. 환경오염노출과 관련해서는 혈중 납과 요중 수은과의 연관성은 찾을 수 없었다. 따라서 본 연구결과 공단지역 어린이들의 색각이상에는 다른 영향요인이 작용했을 것으로 본다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1249-1253
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• 2005

This paper presents a method to model the path loss characteristics in microwave urban line-of-sight (LOS) propagation. We propose new upper- and lower-bound models for the LOS path loss using fuzzy linear regression (FLR). The spread of upper- and lower-bound of FLR depends on max and min value of a sample path loss data while the conventional upper- and lower-bound models, the spread of the bound intervals are fixed and do not depend on the sample path loss data. Comparison of our models to conventional upper- and lower-bound models indicate that improvements in accuracy over the conventional models are achieved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.760-761
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• 2008

This paper deals with the core loss as well as torque characteristics according to the change of stator shape in an interior permanent magnet synchronous motor (IPMSM). The finite element method and functional core loss data obtained by the steinmetz equation are used in order to estimate the core loss. To minimize the core loss caused by the shape of tooth tip, slot-area and volume of permanent magnet, those are all the same in each model. In the end, the ratio between tooth width and yoke thickness to minimize the core loss in the IPMSM is presented in this paper.