• Transactions of the Korean hydrogen and new energy society
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• v.22 no.6
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• pp.895-904
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• 2011

Stratified charge has been thought as one of the ways to avoid a sharp pressure rise on HCCI combustion. The purpose of this study is to evaluate the potential of stratified charge for reducing PRR on HCCI combustion. The pre-mixture with thermal, mixing and EGR stratifications is charged in Rapid Compression Machine. After that, the pre-mixture is compressed and in that process, in-cylinder gas pressure and temperature are analyzed. Additionally numerical calculation with multi-zones modeling is run to know the potential of stratified charge for reducing PRR.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.150-155
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• 1999

비행 Simulator는 조종사가 실제 비행할 때와 같은 느낌을 받도록 구성되어야 하는데 조종사가 비행을 느끼게 되는 것은 여러 가지 감각기관을 통한 종합적인 느낌이다. 시각을 위하여 계기가 현재 비행 상태를 표시해야되고 외부 경치에서 고도, 속도, 자세 및 상승률을 감지하여야 한다. 이런 외부상태를 표시하기 위해서는 조종사의 Stick조작에 의한 비행기의 위치 변화와 속도 등을 실시간으로 계산하여 Graphic Engine과 Actuator로 데이터를 전송하여야 한다. 이러한 Parameter를 결정하기 위해서는 조정사의 조작에 의한 stick의 위치와 그로 인한 항공기의 자세 그리고 상태와 비행 속도 등에 따라 결정되며, 대상 항공기에 대한 제원으로 부터 조종사가 조종간의 이동크기와 조종면의 각 변위와의 관계를 계산하여 위치, 방향과 높이에 관한 Parameter를 계산해 줄 수 있는 방법 구현하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.529-532
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• 2010

본 연구에서는 철근가격 급등과 배근시공도 작성 인력 부족에 대비하여 SDM# 제품군을 사용하여 이음/정착을 고려한 3차원 철근 배근 자동화 기술(RAP)로 철근 배근 자동생성 및 배근시공도 작성 시스템을 개발하였다. 최근 철근가격 급등으로 인한 공사원가상승/인건비 상승/배근시공도 작성 인력 부족 등의 기존현황의 문제점 등을 SDM# 제품군의 철근 배근 자동화 기술(RAP)을 이용하여 자동 철근배근/배근시공도 작성/정밀 골조물량 산출/인력절감/시공 정밀도 향상/골조 공사비 절감 등의 효과와 기존의 현장가공으로 인한 철근 손실률 8%를 공장가공을 적용함으로써 3% 수준으로 낮출 수 있어 5% 내외의 절감효과를 얻을 수 있다. 철근현장가공에서 공장가공 전환으로 골조물량 절감을 기대할 수 있고, 이음/정착/응력분포가 고려된 3차원 철근 배근 자동화 기술(RAP)을 이용하여 자동배근 알고리즘에 의한 배근시공도/가공도 작성 효율을 높이고, 기술 자립을 통해 건설시공 분야의 기술력 향상을 기대할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.936-938
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• 2013

늘어나는 항공 수요의 증가로 인하여 항공 트래픽은 날로 증가하고 있으며, 이에 따라 항공기의 사고 가능성이 점차 늘어나고 있다. 항공기를 안전하게 관제하기 위하여는 항공기의 향후 이동 경로와 그때의 고도와 속도, 예상 도착 시간을 사전에 연산하는 궤도 모델링 기법이 필수적으로 요구되고 있다. 이에 본 논문에서는 궤도 모델링에 필수적으로 사용되는 항공기의 이동 속도와 그때의 고도 계산 알고리즘을 제안하고 환경 파라미터의 변화에 따라 이동 속도가 변경됨을 확인하였다.

• Journal of Chest Surgery
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• v.31 no.5
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• pp.456-465
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• 1998

Cardiopulmonary bypass(CPB) in children is associated with the accumulation of body water after cardiac operation, as a consequence of an inflammatory capillary leak. Following work by Elliott in 1991, modified ultrafiltration(MUF) was introduced after bypass as a means of hemoconcentrating patients and a potential way of removing water from the tissues. We have carried out a prospective randomized study of 20 children undergoing open heart surgery, comparing MUF with nonfiltered controls. MUF was carried out for a mean of 18.9 minutes after completion of CPB to a hematocrit of 37.1%(mean). The mean water volulme removed by the ultrafiltration was 38.4 ml/kg and the mean blood volume retransfused from the oxygenator during the ultrafiltration was 32.1 ml/kg. Fluid balance, hemodynamics, hematocrit, osmolarity and dosage of drug treatment were recorded for 4∼12 hours postoperatively. The results were analyzed using Student t-test and ANOVA, comparing controls(n=10) to MUF(n=10). Blood loss(ml/kg/24hr) was 14.5(mean) in MUF versus 13.7 in controls; blood transfused(ml/kg/24hr) 6.6 in MUF versus 15.2 in controls; plasma transfused(ml/kg/24hr) 65.7 in MUF versus 59.6 in controls. There was rise in arterial blood pressure and hematocrit during MUF. Percent rise of systolic blood pressure was 28.8% in MUF versus 18.7% in controls(p=0.366); percent rise of diastolic blood pressure was 28.8% in MUF versus 8.5% in controls(p=0.135); and percent rise of mean blood pressure was 36.2% in MUF versus 8.2% in controls (p=0.086). Percent rise of hematocrit was 40.0% in MUF versus 23.5% in controls(p=0.002). There was no significant difference in the inotropic requirement and the postoperative serum osmolarity between two groups. The number of days on the ventilator, the duration of stay in the intensive care unit, and the postoperative hospital stay were not significantly different between the two groups.

• Journal of Korea Water Resources Association
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• v.39 no.4 s.165
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• pp.299-311
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• 2006

In this paper it is outlined the methodology of estimating the parameters of water balance analysis method for calculating recharge, using ground water level rises in monitoring well when values of specific yield of aquifer are not available. This methodology is applied for two monitoring wells of the case study area in northern area of the Jeiu Island. A water balance of soil layer of plant rooting zone is computed on a daily basis in the following manner. Diect runoff is estimated by using SCS method. Potential evapotranspiration calculated with Penman-Monteith equation is multiplied by crop coefficients($K_c$) and water stress coefficient to compute actual evapotranspiration(AET). Daily runoff and AET is subtracted from the rainfall plus the soil water storage of the previous day. Soil water remaining above soil water retention capacity(SWRC) is assumed to be recharge. Parameters such as the SCS curve number, SWRC and Kc are estimated from a linear relationship between water level rise and recharge for rainfall events. The upper threshold value of specific yield($n_m$) at the monitoring well location is derived from the relationship between rainfall and the resulting water level rise. The specific yield($n_c$) and the coefficient of determination ($R^2$) are calculated from a linear relationship between observed water level rise and calculated recharge for the different simulations. A set of parameter values with maximum value of $R^2$ is selected among parameter values with calculated specific yield($n_c$) less than the upper threshold value of specific yield($n_m$). Results applied for two monitoring wells show that the 81% of variance of the observed water level rises are explained by calculated recharge with the estimated parameters. It is shown that the data of groundwater level is useful in estimating the parameter of water balance analysis method for calculating recharge.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.4
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• pp.206-214
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• 2001

Cooling rate shows the highest as about 0.7$^{\circ}C$/hr on spring season and the lowest as about 0.3$^{\circ}C$/hr on september at plain place. The correlation coefficient between net radiation and cooling rate from sunrise to sunset was 0.63$^{**}$, It became higher to 0.90$^{**}$ when the wind speed decreased lower than 0.5 m/sec, and it decreased as the wind speed increased. On a clear and calm day, cooling rates were observed as 1.4$^{\circ}C$/hr on the plain (site 1, 2, 3), 1.2$^{\circ}C$/hr on the slope (site 4, 5) and 0.6$^{\circ}C$/hr on the top of mountain (site 6). In condition of the wind speed is 1.2~2 m/sec on a clear and calm day and the temperature on the top of mountain is lower than that of slope and plain, the temperature on the slope (site 4,5) was increased unlike our expectation.ion.

• The Journal of Engineering Geology
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• v.5 no.2
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• pp.129-138
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• 1995

To elucidate the effects of flow rate on the hydraulic fracturing property of andesite, the hydraulic fracturing tests were conducted under three flow rates. As the tests are conducted with 1ml/min, 2ml/min and 3 ml/min under the constant axial load of 40 kN, the breakdown pressures of andesite seem to be constant as 163kg/cm$^2$. The hydraulic fracturing tests were carried out under the temperatures of five stages to elucidate the effects of temperature variation on hydraulic fracturing property of granite. As the tests are carried out under the constant flow rate of 1.7ml/min, with the axial load of 40kN, the breakdown pressures of granite are 168kg/cm$^2$ at room temperature, and 124kg/cm$^2$ at 20$0^{\circ}C$. The breakdown pressure decreases about 25% than that of room temperature with increasing the temperature. Under the controlled flow rates, the initiation pressures of the microcracks of granite are well coincided with the breakdown pressures and these results are also confirmed by the levels of acoustic emission.

• Economic and Environmental Geology
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• v.53 no.5
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• pp.553-564
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• 2020

Transition between explosive and effusive eruption in Ulleung Island is observed in the Nari Scoria Deposits and Albong Trachyandesite (lava dome) origined by dome-building eruption and may be related to factors such as magma influx, ascent rate and degassing. However, the interpretation of them has not been resolved yet because the interaction between these factors is not complex but also the resulting behaviour during eruption is unpredictable. This paper focuses on the explosive and effusive activity perceived during building the Albong lava dome in Nari caldera. Samples were collected along with time from the scoria deposits and lava dome, linked to eruption stage and style of activity. Textures of groundmass feldspar microlites from these samples are quantitatively analyzed, including measurements of areal number density, mean microlite size, crystal aspect ratio, groundmass crystallinity and crystal size. The microlite textures show that shallow pre- and syn-eruptive magmatic processes acted to govern the changing behaviour during the eruption. Transition between explosive and effusive eruption was driven by the dynamics of magma ascent in the conduit, with degassing and crystallisation acting via feedback mechanisms, resulting in a cycle of effusive and explosive eruption.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.195-204
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• 2020

The purpose of this study is to look for the relationship between export weight and control volume, inland cargo, export cargo transport, ship departure. The analysis period were used for a total of 113 monthly data from January 2011 to May 2020. Data were retrieved from the Korean Statistical Information Service of the Statistics Korea. The data used in this study were performed numerical analysis, index analysis and model analysis using the rate of change from the same month of the previous year. In the trend of the increase rate, the amount of control has plummeted from 150% to 60% due to the influence of Corona 19 in the beginning of 2020. At the same time, export weight and export cargo transport also decreased. As a result of the analysis, export weight showed relatively high synchronization with export cargo transport and control volume. On the other hand, export weight and inland cargo showed relatively low synchronization. Export weight is expected to continue in 2020 after the fluctuation rate began to decrease after 2019. If we can find the point of rebound in control volume or export cargo transport in the future, we can predict the point of increase in export weight. We expect to see an increase in export weight as soon as possible.