• 한국농공학회지
• /
• 제31권1호
• /
• pp.117-130
• /
• 1989

In this study, an implicit one-dimensional model, DWRM(Dynamic Wave Routing Model) was developed by using the four-point weighted difference method. By applying the developed model to the Keum River, the parameters were calibrated and the model applicability was tested through the comparison between observed and computed water levels. In addition, the effects of the construction of an estuary dam to the flood wave were estimated as a result of the model application. The results of the study can be summarized as follows; 1. The roughness coefficients were evaluated by comparison between observed and computed water level at Jindu, Gyuam and Ganggyeung station in 1985. The Root Mean Squares for water level differences between observed and computed values were 0.10, 0.11, 0. 29m and the differences of peak flood levels were 0.07, 0.02, 0. 07m at each station. Since the evaluated roughness coefficients were within the range of 0.029-0.041 showing the realistic value for the general condition of rivers, it can be concluded that the calibration has been completed. 2. By the application of model using the calibrated roughness coefficients, the R. M. S. for water level differences were 0.16, 0.24, 0. 24m and the differences of peak flood level were 0.17, 0.13,0.08 m at each station. The arrival time of peak flood at each station and the stage-discharge relationship at Gongju station agreed well with the observed values. Therefore, it was concluded that the model could be applied to the Keum River. 3. The model was applied under conditions before and after the construction of the estuary dam. The 50-year frequency flood which had 7, 800m$^3$/sec of peak flood was used as the upstream condition, and the spring tide and the neap tide were used as the downstream condition. As the results of the application, no change of the peak flood level was showed in the upper reaches of 19.2km upstream from the estuary dam. For areas near 9.6km upstream from the estuary dam, the change of the peak flood level under the condition before and after the construction was 0. 2m. However considering the assumptions for the boundary conditions of downstream, the change of peak flood level would be decreased.

• Korean Chemical Engineering Research
• /
• 제58권1호
• /
• pp.113-121
• /
• 2020

실로퓨트에 대한 Taxus chinensis 유래 7-에피-10-디아세틸파클리탁셀의 흡착을 회분식 실험에서 연구하였다. 흡착 평형 데이터를 Langmuir, Freundlich, Temkin 및 Dubinin-Radushkevich 등온흡착식에 적용한 결과, Langmuir 등온흡착식이 가장 높은 정확도를 나타내었다. 흡착 용량은 온도가 증가함에 따라 감소하였으며, 실로퓨트에 대한 7-에피-10-디아세틸파클리탁셀의 흡착은 적합한 물리적 공정이었다. 흡착 데이터는 유사 이차 동역학 모델과 매우 잘 일치하였으며, 경계층 확산과 입자 내 확산은 흡착 과정에 거의 영향을 미치지 않았다. 실로퓨트에 대한 7-에피-10-디아세틸파클리탁셀 흡착 과정은 발열이며 비자발적이었다. 또한, 등량흡착열은 흡착량에 의존하지 않아 흡착제의 표면 에너지가 균일함을 알 수 있었다.

• 한국해안해양공학회지
• /
• 제8권1호
• /
• pp.44-51
• /
• 1996

해안선에서 장파의 처오름높이의 정확한 산정은 공학적인 측면에서 매우 중요하다. 본 논문에서는 크노이드파 이론을 이용하여 장파의 처오름높이에 관한 연구를 하였다. 크노이드파는 파형이 복잡하여 발생과 처오름높이 산정이 매우 어렵다. 본 연구에서는 경계요소법을 이용하여 급경사 지형에서 크노이드파의 처오름높이를 계산한다. 일반적으로 크노이드파의 처오름높이는 동일한 파고를 갖는 고립파의 처오름높이보다는 작지만, 동일한 파고와 파장을 갖는 정현파의 것보다는 항상 크다. 크노이드파의 처오를높이는 또한 파장이 상대적으로 짧을 경우에는 파장에 따라 단순히 증가하지 않으며, 파장이 매우 커지면 고립파의 처오름높이에 점근적으로 접근한다. 경계요소법에 의해 계산된 크노이드파의 처오름높이는 기존의 수리실험 결과와 대체로 일치한다.

• 한국재료학회지
• /
• 제20권3호
• /
• pp.137-141
• /
• 2010

The $(1-x)La_{0.7}Sr_{0.3}MnO_3(LSMO)/xZnFe_2O_4$(ZFO) (x = 0, 0.01, 0.03, 0.06 and 0.09) composites were prepared by a conventional solid-state reaction method. We investigated the structural properties, magnetic properties and electrical transport properties of (1-x)LSMO/xZFO composites using X-ray diffraction (XRD), scanning electron microscopy (SEM), field-cooled dc magnetization and magnetoresistance (MR) measurements. The XRD and SEM results indicate that LSMO and ZFO coexist in the composites and the ZFO mostly segregates at the grain boundaries of LSMO, which agreed well with the results of the magnetic measurements. The resistivity of the samples increased by the increase of the ZFO doping level. A clear metal-to-insulator (M-I) transition was observed at 360K in pure LSMO. The introduction of ZFO further downshifted the transition temperature (350K-160K) while the transition disappeared in the sample (x = 0.09) and it presented insulating/semiconducting behavior in the measured temperature range (100K to 400K). The MR was measured in the presence of the 10kOe field. Compared with pure LSMO, the enhancement of low-field magnetoresistance (LFMR) was observed in the composites. It was clearly observed that the magnetoresistance effect of x = 0.03 was enhanced at room temperature range. These phenomena can be explained using the double-exchange (DE) mechanism, the grain boundary effect and the intrinsic transport properties together.

• Steel and Composite Structures
• /
• 제25권6호
• /
• pp.671-684
• /
• 2017

Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

• 대한예방한의학회지
• /
• 제7권1호
• /
• pp.17-28
• /
• 2003

We met results like the followings through the literatures and questionnaires about the tasks and solutions about the insurance fee of packed medical herbs. 1) It's turned out that 74.8% of herb doctors agrees to the insurance fee of packed medical herbs. However, in comparison with the same survey of the herb doctor association the percentage of general approval went somewhat lower, and especially the percentage of 'positive approval' became notably lower$(43.7%{\rightarrow}26.5%)$ and the percentage of 'active objection' raised about 2 times$(6.8%{\rightarrow}12.9%)$. Inquiring into the approval reasons on the insurance fee application of packed medical herbs some heads such as 'development toward treatment medical science' and 'decrease of publics burden' were higher than the one of 'management income and expenditure.' 2) As a result of the research, 36.0% of the patients and 42.8% of the residents recognized that the pay range of Chinese herb health insurance is narrow. They recognized that less people have the experiences of Chinese medical hospital use and internal application of the packed medical herbs as they are older, men rather than women. 85.4% of the patients and 74.9% of the residents agreed on the insurance pay of packed medical herbs. It's shown that they agree on the Chinese medical hospital use more as the economic standard is lower, on the insurance pay as they have ever taken the packed medical herbs. In the aspect of increase of insurance fee, 66.7% of the patients and 44.3% of the residents agreed on the insurance pay of packed medical herbs, and 18.1% and 36.1% disagreed on the insurance pay of packed medical herbs. The main objective reason why they disagree on the insurance pay of packed medical herbs was 'because the insurance fee goes up higher,' which answered 95.2% of the patients and 78.8% of the residents. 7.22% of the patients and 1.80% of the residents answered that they can pay more insurance fee in case of the insurance pay of packed medical herbs. However, in the priority order of the insurance pay, it hold the 5th position between 2 target research groups which was less than medical examination, charges for hospital accommodation and taking MRI. 3) According to the result of analysis about the cost of packed medical herbs, current practice price is 115,000 won and the average prime cost of a packed medical herb is 73,000 to 106,000 won. It's examined that the herb doctors regard that 95,000 won will be reasonable when the packed medical herb is payed in insurance. However, it was found out that the public generally thinks that the price would be appropriate on the level of 30,000 to 40,000 won and the percentage of the answers of 20,000 won to 30,000 was fairly high. 4) the central system of a prescription should be change into the central system of demonstration and the sick and wounded. 5) To solve this problem, the government should regulate it to pass by the circulation gradation of [importer, $peasantry{\rightarrow}manufacturer{\rightarrow}wholesaler{\rightarrow}distributor$(Chinese medical hospital, pharmacy dispensary of Chinese medicine)]And it should intervene into the quality and the circulation steps of Chinese medicine through 'the office or organization which is in charge of certification of Chinese medicine' and 'the office or organization which is in charge of the circulation of Chinese medicine.' And some actions such as simple severance, lavation, drying should be included into the conception of manufacture and the boundary between food and medical supplies should be made at a manufactory. And the regulation of standardized goods at one's own house should be improved so that, the peasantry can sell the materials of Chinese medicine only to the manufacturer. 6) In company with the insurance pay of packed medical herbs, the study about the separation of dispensary from medical practice in the Chinese medicine should be accomplished.

• Asian Journal of Atmospheric Environment
• /
• 제8권3호
• /
• pp.162-174
• /
• 2014

An abnormal decrease in ozonesonde sensor signal occurred during air-pollution study campaigns in November 2011 and March 2012 in Mexico City Metropolitan Area (MCMA). Sharp drops in sensor signal around 5 km above sea level and above were observed in November 2011, and a reduction of signal over a broad range of altitude was observed in the convective boundary layer in March 2012. Circumstantial evidence indicated that $SO_2$ gas interfered with the electrochemical concentration cell (ECC) ozone sensors in the ozonesonde and that this interference was the cause of the reduced sensor signal output. The sharp drops in November 2011 were attributed to the $SO_2$ plume from Popocat$\acute{e}$petl volcano southeast of MCMA. Experiments on the response of the ECC sensor to representative atmospheric trace gases showed that only $SO_2$ could cause the observed abrupt drops in sensor signal. The vertical profile of the plume reproduced by a Lagrangian particle diffusion simulation supported this finding. A near-ground reduction in the sensor signal in March 2012 was attributed to an $SO_2$ plume from the Tula industrial complex north-west of MCMA. Before and at the time of ozonesonde launch, intermittent high $SO_2$ concentrations were recorded at ground-level monitoring stations north of MCMA. The difference between the $O_3$ concentration measured by the ozonesonde and that recorded by a UV-based $O_3$ monitor was consistent with the $SO_2$ concentration recorded by a UV-based monitor on the ground. The vertical profiles of the plumes estimated by Lagrangian particle diffusion simulation agreed fairly well with the observed profile. Statistical analysis of the wind field in MCMA revealed that the effect Popocat$\acute{e}$petl was most likely to have occurred from June to October, whereas the effect of the industries north of MCMA, including the Tula complex, was predicted to occur throughout the year.

• 생물환경조절학회지
• /
• 제6권3호
• /
• pp.205-215
• /
• 1997

본 연구에서는 온실 재배 토마토 군락의 열수지에 근거한 증산모델을 구성하고 실험을 통하여 모텔에 필요한 계수의 추정과 모질의 검증을 수행하였다. 온실의 일사략과 엽-대기수증기압차(LVPD)를 매개변수로 하는 기공확산저항 추정식을 구성하여 기공작산저항 실측 자료를 이용하여 추정식의 계수를 추정하였다. 이 추정식으로 기공확산저항 변이의 80％ 이상을 설명할 수 있었으며 추정식에 이용하지 않았던 독립 자료를 이용하여 검정한 결과 추정정도가 높아 증산예측 모델의 구성식으로 이용될 수 있는 것으로 판단되었다. 반투과성 매질의 복사 흡수이론을 적용한 Stanghellini의 식을 다소 변형하여 모델의 군락 순복사 추정식으로 사용하였으며 이 추정식에 의하여 계산된 순복사량은 실측치와 잘 일치하였다. 계수 추정에 사용하지 않았던 독립 자료를 이용하여 순복사 및 기공확산저항 추정식으로 구성된 증산예측 모델의 군락온도 및 증산예측 정도를 검증하였다. 모델에 의하여 계산된 군락 온도, 순간 증산속도 및 일 총 증산량은 실측치와 잘 일치하여 본 연구에서 작성된 증산 예측 모델은 온실 재배 토마토의 환경제어, 관개제어 등에 실용적으로 활용될 수 있을 것으로 판단되었다.

• 한국산학기술학회논문지
• /
• 제19권7호
• /
• pp.265-274
• /
• 2018

빌딩, 자동차, 선박, 항공기 등에서의 곡선보 사용 증가가 이러한 구조물의 동적거동해석에 필요한 정확한 해법 발전에 괄목할 만한 기여를 해왔다. 탄성곡선 보의 안정성거동은 많은 연구자들의 한 과제분야였다. 전통적으로 미분방정식의 해법은 유한치분법이나 유한요소법으로 해결해왔다. 이러한 방법들은 복잡한 기하학적 구조 및 하중에 따른 격자점의 증가로 많은 컴퓨팅시간을 요구한다. 편미분방정식의 해를 구하기 위한 효율적인 방법 중의 하나는 미분구적법이다. 복잡한 기하학적 구조 및 하중 은 컴퓨터 용량을 과도하게 사용할 뿐만 아니라, 복합알고리즘 프로그램의 어려움을 극복하기위하여 미분구적법(DQM)이 많은 분야에 적용되어왔다. DQM을 이용하여 곡선 보의 아크 축 신장을 고려한 내 평면 좌굴을 등분포 하중 하에서 해석하였다. 다양한 매개변수 비, 경계조건, 그리고 열림 각에 따른 임계하중을 계산하였다. DQM 결과는 활용 가능한 다른 엄밀해와 비교하였다. DQM은 적은 격자점을 사용하고도 엄밀해 결과와 일치함을 보여주었다 (0.3% 미만). 다양한 변경에 따른 새로운 결과가 또한 제시 되였고, 그 결과는 곡선 보의 좌굴거동에 중요한 역할을 보여주었고, 다른 수치해석결과 혹은 실험결과비교에 사용될 수 있다.

• 청정기술
• /
• 제24권2호
• /
• pp.135-145
• /
• 2018

전 세계적으로 온실가스 배출량 저감을 위한 다양한 활동을 하고 있다. 국가별로는 UN에 개별 국가별 계획을 제출하기로 합의했으며, 기후변화와 관련한 제도를 운영하고 있다. 또한 기업들은 자체적으로 온실가스 배출량 산정 방법론 개발을 하고 있다. 본 연구에서는 환경영향 감축 효과를 산정하기 위한 방법론의 사전 연구를 수행하였고, 국제적, 국가별, 기업별로 구분하였다. 환경영향 감축 효과는 자동차 언더커버 제품과 유니소재화 제품에 적용하여 비교, 분석하였다. 제품 환경 발자국 감축 평가 방법에 따라 차이가 크게 나타났으며, 주요 원인으로는 시스템 경계의 차이, 데이터 수집 범위, 기존제품 대체량 설정 기준의 차이이다. 방법론별 결과값에 차이가 발생하기 때문에 이해관계자는 제품 환경발자국 감축 결과에 신뢰하지 못하고 있다. 이에 이해관계자가 쉽게 이해할 수 있는 수준의 제품 환경발자국 산정 방법론을 상세히 공개하도록 해야 한다. 장기적으로는 제품 발자국 평가방법의 표준화로 감축 결과에 대한 비교가 가능하게 할 필요가 있다.