• 환경위생공학
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• 제13권3호
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• pp.113-120
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• 1998

For a microbial control of a plant pathogenic Pseudomonas syringae, Bacillus sp. strain BT182-3 was isolated. The strain BT182-3 had a growth inhibition against P. syringae not only on agar plate but also on cultured broth. After heat treatment at $40^{\cird}C$ and $80^{\cird}C$ for 30min, the lytic substance from the strain BT182-3 had about 52% remaining activity and 17% remaining activity, respectively. The optimal pH and temperature of the lytic substance was 6.0 and $28^{\cird}C$, respectively. Germination ratio of healthy radish seeds was 87% at $25^{\cird}C$ for 5 days in 0.8% saline, and that of the radish seeds infected with P. syringae was 67%, while that of the radish seeds treated with cultured broth of the strain BT182-3 was 90%. The 5-days healthy radish seedlings were 3.90cm at high and the seedlings infected with P. syringae were 3.06cm at high, while the seedlings treated with cultured broth of the strain BT182-3 were 4.30cm at high. The growth of the radish seedlings infected with P. syringae was inhibited after cultivation for 40days on pots, while the growth of the infected radish seedlings with P. syringae was recovered at stem length, root length and total weight at the same as the healthy seedlings after treatment of a lytic substance from the strain BT182-3.

• 한국재료학회지
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• 제18권5호
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• pp.272-276
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• 2008

In submicron MOSFET devices, maintaining the ratio between the channel length (L) and the channel depth (D) at 3 : 1 or larger is known to be critical in preventing deleterious short-channel effects. In this study, n-type SOI-MOSFETs with a channel length of $0.1\;{\mu}m$ and a Si film thickness (channel depth) of $0.033\;{\mu}m$ (L : D = 3 : 1) were virtually fabricated using a TSUPREM-4 process simulator. To form functioning transistors on the very thin Si film, a protective layer of $0.08\;{\mu}m$-thick surface oxide was deposited prior to the source/drain ion implantation so as to dampen the speed of the incoming As ions. The p-type boron doping concentration of the Si film, in which the device channel is formed, was used as the key variable in the process simulation. The finished devices were electrically tested with a Medici device simulator. The result showed that, for a given channel doping concentration of $1.9{\sim}2.5\;{\times}\;10^{18}\;cm^{-3}$, the threshold voltage was $0.5{\sim}0.7\;V$, and the subthreshold swing was $70{\sim}80\;mV/dec$. These value ranges are all fairly reasonable and should form a 'magic region' in which SOI-MOSFETs run optimally.

• Steel and Composite Structures
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• 제3권4호
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• pp.261-275
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• 2003

Truss members built-up with double angles back-to-back have monosymmetric cross-section and twisting always accompanies flexion upon the onset of buckling about the axis of symmetry. Approximate formulae for calculating the buckling capacity are presented in this paper for routine design purpose. For a member susceptible only to flexural buckling, its optimal cross-section should consist of slender plate elements so as to get larger radius of gyration. But, occurrence of twisting changes the situation owing to the weakness of thin plates in resisting torsion. Criteria for limiting the leg slenderness are discussed herein. Truss web members in compression are usually considered as hinged at both ends for out-of-plane buckling. In case one (or both) end of member is not supported laterally by bracing member, its adjoining members have to provide an elastic support of adequate stiffness in order not to underdesign the member. The stiffness provided by either compression or tension chords in different cases is analyzed, and the effect of initial crookedness of compression chord is taken into account. Formulae are presented to compute the required stiffness of chord member and to determine the effective length factor for inadequately constrained compressive diagonals.

• 한국소음진동공학회논문집
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• 제13권2호
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• pp.83-91
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• 2003

Pantograph design Process must be considered in terms of stability of aerodynamics and reduction of aeroacoustics. Furthermore pantograph needs to be insensible to severe circumstance condition like typhoon, tunnel, a change of season. In this paper, robust design of panhead sections is conducted based on the Taguchi's design of experiment method. In the aeroacoustic noise analysis, an acoustic analogy using the Ffowcs Williams and Hawkings(FW-H) equation is used to calculate the flow induced sound pressure level in aeroacoustics. From the near-field CFD analysis data, the far-field noise is predicted at the positions of 25 m away from Pantograph. Based on aerodynamic(CFD) and aeroacoustic(FW-H) analysis data, the optimal sizing and Positioning of panhead elements are determined using robust design optimization method. Design parameters such as thickness, length and radius are controllable factors, while outdoor air temperature and atmospheric pressure are considered as uncontrollable factors in the context of Taguchi's approach. A number of CFD simulation and aeroacoustic analysis are performed based on orthogonal arrays. In this paper, two-step optimization method is used as a parameter design procedure. It is executed using signal to noise(S/N) ratio and analysis of means(ANOM) method. So Thus, an optimal level of design parameters Is extracted to minimize the disconnection ration between contact strips and catenary system, and reduce the far-field aeroacoustic noise.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1438-1441
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• 2005

To establish of standard technique of nano-length measurement in 2D plane, new AFM system has been designed. In this system, measurement uncertainty is dominantly affected by the Abbe error of XY scanning stage. No linear stage is perfectly straight; in other words, every scanning stage is subject to tilting, pitch and yaw motion. In this paper, an AFM system with minimum offset of XY sensing is designed. And XY scanning stage is designed to minimize rotation angle because Abbe errors occur through the multiply of offset and rotation angle. To minimize the rotation angle optimal design has performed by maximizing the stiffness ratio of motion direction to the parasitic motion direction of each stage. This paper describes the design scheme of full AFM system, especially about XY stage. Full range of fabricated XY scanner is $100um\times{100um}$. And tilting, pitch and yaw motion are measured by autocollimator to evaluate the performance of XY stage. Using this AFM system, 3um pitch specimen was measured. As a result, the uncertainty of total system has been evaluated.

• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.756-762
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• 2001

As a component for a recirculating aquaculture system, a new strain of denitrifying bacterium was isolated from municipal sewage. The isolate was motile by means of one polar flagellum, catalase-positive, and a Gram-negative rod-shaped cell measuring $0.5-0.6{\mu}m$ in width and $1.3-1.9{\mu}m$ in length. The isolate was identified as Pseudomonas fluorescens and produced dinitrogen gas via the reduction of nitrate. The optimal growth conditions (pH, temperature, carbon source, and C/N ratio) of the isolate were found to be 6.8, $30^{\circ}C$, malate, and 3, respectively. Under optimal growth conditions of P. fluorescens, dinitrogen gas was first detected in the exponential growth phase, then a small amount of nitrite was developed and converted to dinitrogen gas in the stationary phase. Pseudomonas fluorescens cells were immobilized in modified polyvinyl alcohol (PVA) gel beads, and the maximum denitrification rate was measured as $36.6 {\mu}lN_2h^-1$ per bead with an optimum cell loading of $20mg {\mu}l^-1$ and $2\%$ sodium alginate added to the PVA gel. The operating stability of the modified PVA gel beads remained unchanged for up to 43 repeated batches.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.258-261
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• 2003

액체로켓 엔진에 사용되는 가스발생기의 최적설계와 연소해석을 수행하였다. 추진제는 RP-1/LOx 이고, open cycle터보펌프 시스템을 사용하였으며, 가스발생기는 농후(fuel-rich)연소를 적용하였다. 최적설계의 목적함수는 주연소실의 비추력이 최대가 되는 것으로 하였다. 설계변수는 가스발생기의 O/F비, 유량(mass flow rate into gas generator), 터빈 노즐 출구 각, 부분분사비, 그리고 터빈 원주속도로서 이들을 이용하여 가스발생기의 열역학적 성능을 계산하였고, 설계제한조건인 가스발생기 연소실 총온도와 터빈-펌프의 출력일치(matching)를 만족하면서 목적함수를 최대화 할 수 있는 가스발생기의 형상과 성능조건을 확인하였다. 연소해석을 통하여 난류고리 장착에 따른 연소가스의 혼합길이와 연소실 직경을 검토하고, 반경방향의 온도분포 등을 살펴보았다.

• 생물환경조절학회지
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• 제33권1호
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• pp.30-36
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• 2024

최근 국내에서 개발된 송풍식 양파 줄기절단기를 수확기 양파 엽 절단에 활용할 경우 적정 작업 조건을 구명하기 위해서 이 실험을 수행하였다. 처리구 중 식물체 엽 건조가 가장 많이 진행된(엽 건조 정도 : 66.3%, 엽 수분함량 : 50.5%) 6월 20일 엽 절단 처리구에서 평균 잔여 엽장은 6.7±3.5cm로서 작업 후 적정 잔여 엽장에 해당되는 범위인 4-10cm에 포함되므로 기계 엽 절단 성능이 처리구 중 가장 우수한 것으로 판단된다. 줄기절단기 이용 양파 엽 기계 절단 시 평균 작업 속도는 0.17m·s^-1였는데, 이는 인력 엽 절단 처리구의 평균 작업 속도인 0.05m·s^-1보다 3.4배 정도 빨랐으며, 이를 통해 해당 기종을 이용하여 10a 면적을 작업할 경우에는 인력 작업(1인 기준)에 비해 2.6시간 정도를 절감할 수 있을 것으로 기대된다. 또한 기계 엽 절단 처리구에서의 손상구 발생률은 1.3%로서 인력 엽 절단 처리구의 0.0%에 비해 높았는데, 이로 인해 기계 엽 절단 처리구가 인력 엽 절단 처리구보다 저장 중 양파 구 부패율이 평균적으로 높았던 것으로 판단된다. 처리별 저장 특성을 살펴보면, 저장 8개월 후 구 부위(기부, 정부)별 부패율은 기계 엽 절단 후 잔여 엽장이 5.0cm 미만인 처리구에서 잔여 엽장이 5.0cm 이상인 처리구보다 높았다. 이는 잔여 엽 길이가 5.0cm 미만인 처리구에서는 5.0cm 이상인 처리구보다 저장 중 구 부패를 유발하는 병원균의 감염이 쉬우므로 장기 저장 시 부패율이 높은 것으로 생각된다. 본 실험 결과와 실험 기종의 성능 목표(작업 후 잔여 엽장 : 5cm) 및 양파 수확 시 적정 잔여 엽장에 관한 기존의 연구결과 등을 종합적으로 고려할 경우, 본 실험에 사용된 줄기절단기 이용 양파 엽 절단 시 양파의 적정 잔여 엽장은 5-10cm 정도일 것으로 판단된다.

• 정보처리학회논문지A
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• 제16A권6호
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• pp.509-518
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• 2009

본 논문에서는 입력 선분들 상에 위치하며, 이들을 일정한 길이로 분할하는 가상 노드 포탈을 이용하여 입력 선분들을 모두 연결하는 근사 선분 최소 신장 트리를 빠른 시간 내에 찾는 방법을 제안한다. 이 근사 선분 최소 신장 트리는 통신선, 도로 및 철도망의 연결 등에 활용될 수 있다. 3000개의 입력 선분에 대해 제안된 방법으로 생성된 근사 트리는, 포탈 간격이 0.3인 경우에 최적 선분 최소 신장 트리와 비교하여 1.8% 의 길이가 증가한 반면에 트리 생성 시간은 29.74%의 감소를 보였고, 0.75의 경우 2.96%의 길이의 증가와 39.96%의 트리 생성 시간의 절감을 보였다. 이는 약간의 길이 증가를 허용하면서 짧은 시간 내에 선분 연결 트리를 생성해야 하는 응용에 잘 적용될 수 있음을 보인다. 또한 제안 된 방법은 포탈 간격, 포탈 포기 비율 등을 외부 인자로서 조절하여, 목적에 따른 트리 길이 또는 트리 생성 시간에 중점을 둔 근사 선분 최소 신장 트리 생성이 가능함을 보인다.

• 상하수도학회지
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• 제29권5호
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• pp.559-564
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• 2015

Distribution basins are used widely in the water treatment process. Uniform distribution at the distribution basin is an important because it affect precipitation efficiency of sedimentation basin. Generally distribution basin has a free surface water and is consisted of a weir. Study result, when inflow of distribution basin is less, amount of overflow is much at the nearest weir from the inlet. But when inflow is much, amount of overflow is much at the far weir from the inlet. The difference of distribution amount at the pipe is affected by the curvature and length of the pipe. The magnitude of the effect is determined by the relative energy loss and the flow state of the distribution basin. Optimization of the response surface method for minimizing an amount of deviation of the distribution is a very useful technique to determine the optimal ratio of the valve opening.