• 대한기계학회논문집B
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• 제37권5호
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• pp.531-538
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• 2013

원심압축기에서 볼류트는 임펠러와 디퓨저를 통해 나온 유동을 모아주는 역할을 한다. 압축기의 운전점에 따라 볼류트 내부 발생하는 와류의 세기나 패턴이 달라진다. 압축기 설부에서는 압축기의 운전점에 따라 재유입 유동의 특성이 변화하고, 이러한 특성은 압축기의 성능 및 탈설계점에서의 특성을 이해하는데 중요한 역할을 한다. 본 연구에서는 PIV를 이용하여 압축기의 운전점에 따라 볼류트 내부에 발생하는 스크롤 와류를 측정하였으며, 압축기 설부 근처에서 유동장을 측정한 결과 유량계수가 감소할수록, 설부 측에 발생하는 박리영역이 줄어들고 압축기로 재유입되는 유동이 커지는 것을 알 수 있다.

• 아시안잔디학회지
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• 제26권2호
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• pp.102-109
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• 2012

Typhula incarnata에 의한 설부병 방제를 위한 살균제의 효과를 골프코스에서 평가하였다. 살균제의 살포효과, 살균제의 혼용효과, 살균제의 살포방법에 의한 효과 및 살포시기에 의한 설부병의 방제효과에 미치는 영향을 용평 골프장에서 평가하였다. 무처리구는 3종의 살균제처리구보다 병 피해가 더욱 심각하였다. 3종의 살균제(Azoxystrobin, propiconazole, tebuconazole)는 Kentucky bluegrass 종과 creeping bentrasss 종의 잔디에서 80% 이상의 설부병을 방제하는 효과가 있었다. 2종 이상의 혼용살포에 의한 설부병의 방제효과는 Kentucky bluegrass 종에서 93% 이상 방제효과가 있었다. Azoxystrobin 살균제를 관주와 경엽살포에 대한 설부병 방제 효과는 2종의 잔디에서 모두 유의성의 차이가 없었다. 살균제 살포시기에 따른 설부병 방제 효과는 tebuconazole 살포구에서 유의성 있었다. 이른 가을에 살포하는 것이 더 효과적이었다.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1341-1347
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• 2002

In order to improve efficiency of a system with three-dimensional flow characteristics, this paper presents a new method that overcomes three-dimensional effects by using two-dimensional CFD and neural network. The method was applied to shape optimization of cut-off in a multi-blade fan/scroll system. As the entrance conditions of two-dimensional CFD, the experimental values at the positions out of the inactive zone were used. The distributions of velocity and pressure obtained by two-dimensional CFD were compared with those of three-dimensional CFD and experimental results. It was found that the distributions of velocity and pressure have qualitative similarity. The results of two-dimensional CFD were used for teaming as target values of neural network. The optimal angle and radius of cut-off were determined as 71$^{\circ}$and 0.092 times the outer diameter of impeller, respectively. It is quantified in the previous report that the optimal angle and radius of cut-off are approximately 72$^{\circ}$and 0.08 times the outer diameter of impeller, respectively.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.225-231
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• 2003

In order to improve efficiency of a system with three-dimensional flow characteristics, this paper presents a new method that overcomes three-dimensional effects by using two-dimensional CFD and response surface method. The method was applied to shape optimization of cut-off in a multi-blade fan/scroll system. As the entrance conditions of two-dimensional CFD, the experimental values at the positions out of the inactive zone were used. In order to examine the validity of the two-dimensional CFD the distributions of velocity and pressure obtained by two-dimensional CFD were compared with those of three-dimensional CFD and experimental results. It was found that the distributions of velocity and pressure show qualitatively similarity. The results of two-dimensional CFD were used for constructing the objective function with design variables using response surface method. The optimal angle and radius of cut-off were determined as $72.4^{\circ}$ and 0.092 times the outer diameter of impeller, respectively. It is quantified the previous report that the optimal angle and radius of cut-off are approximately $72^{\circ}$ and 0.08 times the outer diameter of impeller, respectively.

• 아시안잔디학회지
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• 제21권2호
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• pp.147-154
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• 2007

2004년 3월에 전라북도에 위치한 한 골프장의 켄터키 블루그래스와 퍼레니얼 라이그래스에 설부병이 발병되었다. 감염된 잔디잎들은 서로 엉켜저 매트화 되고, 흰색에서 회백색의 균사체들로 덮여있었다. 균핵들은 잔디의 엽신, 엽초 및 관부 위에 형성되어 있었다. 이병 잎으로부터 분리된 곰팡이는 직경이 1.4 mm 미만의 밝은 핑크에서 갈색의 불규칙한 모양의 균핵과 꺽쇠연결체, 흰색의 균사체 등을 형성하여 Typhula incarnata와 같은 특징을 보였다. 분리된 T. incarnata의 균사생육 적온은 $5{\sim}15^{\circ}C$이었다. 원인균의 ribosomal RNA IST1의 부분 염기서열은 GeneBank database에 등록된 T. incarnata의 부분 염기서열과 91%로의 상동성을 보여 T. incarnata로 동정되었다. 실내 약제방제 시험결과 14개 살균제 중 iprodione, tebuconazole, polyoxin D, flutolanil, hexaconazole, tolclofos-methyl, fosetyl-Al, mepronil, pencycuron+ tebuconazole 및 fenarimol 살균제들은 추천농도에서 완전하게 균생장을 억제하였다. 포장시험에서, 이들 살균제와 thifluzamide와 thiram과 같은 살균제들은 다소 방제효능의 정도 차이는 있지만 효과적으로 잔디 설부병을 방제하였다.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1139-1147
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• 2000

This paper describes that the size of inactive zone can be directly applied to design multiblade fan/scroll system. From the experimental studies using a five hole pitot tube and smoke test, it is found that the size of inactive zone has linear relations with the mean velocity of impeller inlet and cut-off angle gives a great influences to the fan efficiency. For the practical design, a function related with geometric parameters(i.e. inner radius, cord length, cut-off clearance and cut-off angle) of fan/scroll system is suggested. By using these formulas, the size and distribution of inactive zone can be predicted without the measurements through the full domain, it can be possible to use them to know the efficiency improvement for new model designed.

• 한국유체기계학회 논문집
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• 제6권2호
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• pp.15-22
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• 2003

Comprehensive study on a centrifugal blower for air-purifier involving a few physical filters for percolation process has been accomplished for an optimal design of the air handling system. The filtering media causes a flow resistance for induced flows by a rotating impeller. The present methodology is to adopt PIV system for velocity measurements and wind tunnel connected with an anechoic chamber for total performance test of the blower. Trial prototypes for the blades of a rotor and casing are presented for satisfaction of both flow rate and noise level set by design objectives. Tapered blades with a special casing for a fan show good performance data. The results of velocity fields also explain the reason of improvements of the blower performance.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.65-68
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• 2004

The design procedure for centrifugal blower with high inlet resistance is not presented yet. Overall fluid dynamic performance is estimated for comparison between the case of atmospheric inlet condition and the present model. Detail information between blades is prepared by using a commercial program, SCRYU-Tetra. A centrifugal blower with large inlet pressure is adopted in an air purifier having filtering devices. As the inlet residence increases the flow rate of the system is decreased. In parallel, outlet area of the system affects the performance of the system in the sense of flow balance. Consequently, the flow balance between the inlet and outlet becomes an important parameter for the design of the scroll casing for the centrifugal blower with high inlet pressure.

• 한국전산유체공학회지
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• 제8권1호
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• pp.1-7
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• 2003

The present study has conducted the analysis of flows in a blower with double suction. The air handling system is for supplying air flows into a plant. The present system has a couple of impellers in axial direction for enhanced flow rate. Main interest lies on the improvements of static pressure rise and total efficiency of the system. The present treatment of the reform is to secure a spatial distance between the fan and the casing of the system and change the shape of the cut-off part. The resultant performance after the reform shows increased pressure-rise and efficiency of the system

• 대한두경부종양학회지
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• 제27권1호
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• pp.74-76
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• 2011

Ectomesenchymal chondromyxoid tumor is a rare benign tumor. It occurs uniquely on the oral cavity particularly the tongue. It was first described in 1995, and only 36 cases were reported in the literature. We report a case of ectomesenchymal chondromyxoid tumor in a 67-years-old male, who presented with an asymptomatic, firm, round shaped mass on the dorsum of the tongue. The lesion was completely excised and confirmed as ectomesenchymal chondromyxoid tumor on histopathological examination.