• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.7-14
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• 2002

In this paper, neutral networks are used to build models of oxide film etched In CHF$_3$/CF$_4$ with a magnetically enhanced reactive ion etcher(MERIE). A statistical 2$\^$4-1/ experimental design plus one center point was used to characterize relationships between process factors and etch responses. The factors that were varied include radio frequence(rf) power, pressure, CHF$_3$ and CF$_4$ flow rates. Resultant 9 experiments were used to train neural networks and trained networks were subsequently tested on its appropriateness using additionally conducted 8 experiments. A total of 17 experiments were thus conducted for this modeling. The etch responses modeled are dc bias voltage, etch rate and etch uniformity A qualitative, good agreement was obtained between predicted and observed behaviors.

• 한국환경과학회지
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• 제23권9호
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• pp.1655-1662
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• 2014

A comprehensive fractionation technique was applied to a set of water samples obtained along drinking water treatment process with ozonation and biological activated carbon (BAC) process to obtain detailed profiles of dissolved organic matter (DOM) and to evaluate the haloacetic acid (HAA) formation potentials of these DOM fractions. The results indicated that coagulation-sedimentation-sand filtration treatment showed limited ability to remove hydrophilic fraction (28%), while removal of hydrophobic and transphilic fraction were 57% and 40%, respectively. And ozonation and BAC treatment showed limited ability to remove hydrophobic fractions (6%), while removal of hydrophilic and transphilic fractions were 25% and 18%. The haloacetic acid formation potential (HAAFP)/dissolved organic carbon (DOC) of hydrophilic fraction was the highest along the treatment train and HAAFP/DOC of hydrophilic fraction was higher than hydrophobic and transphilic fraction as 23%~30%, because of better removal for hydrophobic fraction both in concentration and reactivity.

• 한국항해항만학회지
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• 제30권3호
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• pp.181-187
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• 2006

선형파 이론에 의한 파랑스펙트럼 분포에 의해서는 30m 크기의 파랑은 현실적으로 거의 발생 불가능하다고 인식되어 왔다. 그러나 최근의 위성 영상을 이용한 조사에 의해 3주간의 기간 동안 25m 이상의 거대파가 10개 이상 관측됨에 따라 실해역에서 빈번히 마주칠 수 있는 현상임이 입증되었으며 이에 따라 지금까지 원인 불명으로 치부되어 왔던 많은 해양 재난이 거대파에 의해 발생했던 것으로 추정되고 있다. 거대파의 발생 원인으로는 파군 형성과 관련한 파고분포 특성의 변화, 전파하는 파군의 비선형 공명간섭 등이 제기되고 있으나, 그 출현의 복잡성과 자료의 부족 등으로 아직 명확하게 해명되지 못하고 있다. 본 연구에서는 실해역에서 발생하는 거대파의 실태 및 선형 및 비선형 파랑집중 이론에 근거한 거대파 발생 기구를 고찰하였으며, 비선형 파랑전파를 모사할 수 있는 수치모형을 개발하여 비선형 파랑 집중에 의한 거대 파랑의 형성을 모사하였다.

• 한국지반공학회논문집
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• 제29권1호
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• pp.5-12
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• 2013

철도노반에서 임계속도효과는 시간영역에서의 유사-공진현상으로서 차량의 주행속도와 노반표면파의 군속도대역이 중첩되면서 에너지가 증폭되는 현상을 의미한다. 과거에는 열차의 주행속도가 낮고 지반의 군속도가 높았기 때문에 문제가 되지 않았으나, 열차속도가 고속화되면서 임계속도효과가 궤도틀림에 영향을 미치는 것으로 보고되고 있다. 현재까지는 임계속도에 대하여 주로 이론적인 분석만 제시되었는데 실질적인 임계속도효과를 효율적으로 평가하기 위해서는 궤도 및 노반의 지지강성을 현장조건과 유사하게 고려하는 것이 필요하다. 그래서 본 논문에서는 유한요소해석을 이용하여 궤도 및 노반의 지지조건을 고려한 임계속도해석을 수행하였다. 궤도조건은 자갈궤도와 콘크리트궤도로 구분하였으며 노반의 지지강성은 10~300MPa범위에서의 임계속도영향을 평가하였다. 해석결과 노반의 지지강성에 따른 변형증폭을 확인하였으며, 궤도지지조건에 대한 임계속도영향도 매우 큰 것으로 나타났다.

• 한국철도학회논문집
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• 제10권5호
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• pp.473-479
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• 2007

KTX 인수시험 시 차량 후미부에서 횡진동이 발생하여, 차륜의 답면구배를 1/40에서 1/20로 변경하여 횡진동 문제를 해결하였다. 그러나 차륜의 답면구배를 변경하면 차량의 임계속도 및 주행 안전성에 영향을 미치기 때문에 1/20 차륜에 대한 주행 안전성에 대한 검토 요구된다. 본 논문에서는 VAMPIRE를 이용하여 KTX 1편성 20량을 모델화하여 주행 안전성 및 임계속도를 계산하였으며, 계산결과의 타당성을 검토하기 위해서 KHST차량의 시험결과와 비교하였다. 해석결과 차륜답면이 0.3인 경우 임계속도는 375km/h이상이었으며, 차륜의 답면구배가 1/20인 경우 1/40보다 곡선 추정성이 우수한 것을 알았다. 또한 기존선 주행 시 차량의 속도향상 가능성을 파악하기 위해서 계산한 결과 직선구간에는 10%속도 향상이 가능하지만, 곡선구간에는 기존차량의 속도와 동일하게 운행하는 것이 유리하다는 것을 알았다.

• 한국소음진동공학회논문집
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• 제12권10호
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• pp.758-765
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.917-923
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the KHST test train. The object of this study was 3 kind of cars; trailer car(TT2), motorized car(TM1) and power car(TP1) and the predicted noise was calculated for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from each manufactures. Some of noise sources which were not available in project team, were chosen by experiences of ODS. Internal noise level of each car were predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated of each section of car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is floor in terms or structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TM1 are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TM1 are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• Journal of Microbiology and Biotechnology
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• 제1권2호
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• pp.136-141
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• 1991

Optimum culture conditions for the formation of nitrile hydratase by Brevibacterium sp. CH2 were investigated. Addition of ferric and ferrous ions greatly increased the nitrile hydratase formation. The effects of nitriles, amides, and acids as an inducer on the formation of nitrile hydratase were investigated. Isobutyramide was the best inducer among the tested compounds. When Brevibacterium sp. CH2 was cultivated for 23 h at $30^{\circ}C$ in a optimized medium containing 15 g of glucose, 5 g of bacto peptone, 3 g of yeast extract, 3 g of malt extract, 1 g of $KH_2$$PO_4$, 1 g of $K_2$$HPO_4$, 1 g of NaCl, 0.5 g of isobutyramide, 0.2 g of MgSO$_4$ㆍ7$H_2O$, and 0.02g of $FeSO_4$ㆍ$7H_2$O per liter of distilled water with pH controlled at 7.1, the maximum total activity was 665 units/ml of the culture broth and the specific activity was 70 units/mg of the dry cells. The medium optimization increased the specific activity of Brevibacterium sp. CH2 2.2 times.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1956-1962
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• 2010

The formation of diverse spiral waves was studied in a polyacrylamide gel membrane with ruthenium(4-vinyl-4'-methyl-2,2'-bipyridine)bis(2,2'-bipyridine)bis(hexafluorophosphate) by a gas-free Belousov-Zhabotinisky (BZ) reaction system containing 1,4-cyclohexanedione (1,4-CHD). The gel membrane was found to be receptive for observing propagating waves since a clearer wave-train is obtained during a long reaction time without any disturbance from the immobilized metal catalyst which can be dissolved into the highly acidic solution of the BZ system. The distinctive waves in the system basically depend on both $BrO_3$ and 1,4-CHD in the initial phase, and are influenced by the intensity of illumination of visible light.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.143-149
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• 2008

The present study is mainly motivated to investigate the vaporization, auto-ignition and spray combustion processes in DI diesel engine using DME and n-heptane. In order to realistically simulate the dimethyl ether (DME) spray dynamics and vaporization characteristics in high-pressure and high-temperature environment, the high-pressure vaporization model has been utilized. The interaction between chemistry and turbulence is treated by employing the Representative Interaction Flamelet (RIF) model. The detailed chemistry of 336 elementary steps and 78 chemical species is used for the DME/air reaction. Based on numerical results, the detailed discussion has been made for the distinctly different combustion characteristics of DME diesel engine in term of vaporization, ignition delay, pollutant formation, and heat release rate.