• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.236-236
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• 2011

본 연구 축전 결합형 고주파 플라즈마(CCP) 식각장비에 펄스 직류(Pulse DC) 전원을 인가하여 오실로스코프(oscilloscope)를 분석하여 전기적 특성을 평가하는 것이다. 펄스 직류전원 플라즈마 시스템에서는 다양한 변수를 이해하여야 한다. 본 실험에서 사용한 공정 변수는 Pulsed DC Voltage 300~500 V, Pulsed DC reverse time $0.5{\sim}2.0{\mu}s$, Pulsed DC Frequency 100~250 kHz 이었다. 실험 결과를 정리하면 1) Pulsed DC Voltage 가 증가할수록 Input voltage의 최대값은 336~520 V, 최소값은 -544~-920 V로 변하여 피크 투 피크 (peak to peak)값은 880~1460 V로 증가였다. Input current 또한 최대값은 1.88~2.88 A, 최소값은 -0.84~-1.28 A로 변하여 피크 투피크 값은 2.88~4.24 A로 증가하였다. 이는 척에 인가되는 전류와 파워의 증가를 의미한다. 2) Pulsed DC reverse time이 증가하면 Input voltage와 Input current값이 증가했다 (Input voltage의 피크 투 피크 값은 1200~1440 V, Input current의 피크 투 피크 값은 3.56~4.56 A). 3) Pulsed DC frequency가 증가하면 주기가 짧아져 Input voltage와 Input current값이 증가 한다 (Input voltage의 피크 투 피크 값은 900~1320 V, Input current의 피크 투 피크 값은 2.36~3.64 A). 결론적으로 펄스 직류 플라즈마의 다양한 전기적 변수들은 반응기 내부에 인가되는 Input voltage와 Input current의 값에 큰 영향을 준다는 것을 알 수 있었다.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.21-29
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• 2015

This paper proposes a novel two-tier optimization approach for decision making in many-objective problems. Because the Pareto-optimal solution ratio increases exponentially with an increasing number of objectives, simply finding the Pareto-optimal solutions is not sufficient for decision making in many-objective problems. In other words, it is necessary to discriminate the more preferable solutions from the other solutions. In the proposed approach, user preference-oriented as well as diverse Pareto-optimal solutions can be obtained as candidate solutions by introducing an additional tier of optimization. The second tier of optimization employs the corresponding secondary objectives, global evaluation and crowding distance, which were proposed in previous works, to represent the users preference to a solution and the crowdedness around a solution, respectively. To demonstrate the effectiveness of the proposed approach, decision making for some benchmark functions is conducted, and the outcomes with and without the proposed approach are compared. The experimental results demonstrate that the decisions are successfully made with consideration of the users preference through the proposed approach.

• Spatial Information Research
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• v.19 no.1
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• pp.13-19
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• 2011

As an urbanization is in progress, the change of the planimetric features and topography including high-rise residential buildings commonly occur. The change of the planimetric features and topography causes occurrence of the strong wind and wind speed increase or decrease due to the effect of planimetric features and topography on the windward side even though the wind blows with the same speed. In the design standard, this change by wind speed is defined as the velocity pressure exposure coefficient, the value of coefficient is estimated and reflected by ground surface roughness, but in a reality, ground surface roughness is determined in accordance with the subjective judgement of designer and then the velocity pressure exposure coefficient is estimated, moreover the research and data for classification of ground surface roughness are insufficient. In this paper, we will estimate the velocity pressure exposure coefficient by the quantified method for classifying ground surface roughness by using GIS according to the height of a building targeting area where high-rise residential buildings are built lately. When the structure subjected to wind load is designed, reasonability of design and safety of structure will be more improved by using the estimation method of velocity pressure exposure coefficient presented in this study.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.413-420
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• 2019

The purpose of the present study is to develop a model for predicting hypercholesterolemia using an integrated set of body fat mass variables based on machine learning techniques, beyond the study of the association between body fat mass and hypercholesterolemia. For this study, a total of six models were created using two variable subset selection methods and machine learning algorithms based on the Korea National Health and Nutrition Examination Survey (KNHANES) data. Among the various body fat mass variables, we found that trunk fat mass was the best variable for predicting hypercholesterolemia. Furthermore, we obtained the area under the receiver operating characteristic curve value of 0.739 and the Matthews correlation coefficient value of 0.36 in the model using the correlation-based feature subset selection and naive Bayes algorithm. Our findings are expected to be used as important information in the field of disease prediction in large-scale screening and public health research.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.104-104
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• 2003

본 포스터에서는 다목적 위성 2호의 주 탑재체인 MSC(Multi-Spectral Camera)가 TDI(Time Delayed Integration) 방식을 채택함에 따라, TDI에 의해 MSC 영상 자료가 어떻게 영향을 받게 되는 지를 연구한 내용을 설명한다. MSC는 지상 해상도가 1m인 고해상도에서 영상을 촬영하기 때문에 상대적으로 입사 광량이 부족한 문제를 안고 있음에 따라 32 line의 TDI 방식을 사용한다. TDI 방식을 사용하여 MSC에서 직하방향으로 영상을 촬영할 경우, 영상의 가운데 pixel에서 멀어질수록 TDI에 의해 영상의 MTF 값이 떨어지는 결과가 발생한다. 또한, 다목적 위성 2호는 Roll 축을 중심으로 $\pm$30도 Pitch 축을 중심으로 $\pm$30도 tilt를 하여 영상을 촬영하도록 운영될 예정이기 때문에 더더욱 TDI에 의채 영상의 MTF 값이 떨어지는 결과가 발생하게 된다. 이외에도 TDI는 다목적 위성 2호의 고도가 감소하거나, Yaw 축의 변화, Jitter 등에 의해서도 영상의 MTF 값이 감소하게 된다. 물론 MSC CCD pixel의 sampling rate인 Line Rate 값을 각각의 경우에 따라 적절한 값을 부여함으로써 TDI에 의한 MTF 값의 감소를 많은 부분은 수습할 수 있으나 완벽한 보정은 힘든 상황이다.

• Journal of the Korean GEO-environmental Society
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• v.22 no.2
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• pp.5-13
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• 2021

In this study, as the production of high-strength steel pipes due to the development of steel materials, the stability and applicability of the soil nailing method using high-strength steel pipes were evaluated. Rebars used as reinforcement in the soil nailing method are the same in order to determine the behavioral characteristics and the effect of increasing the reinforcement when replacing it with a high-strength steel pipe of a diameter, a field test were conducted to confirm the stability. As a result of the tensile test, the measured strain is smaller than the strain in the theoretical equation, so it can be seen that the behavior is similar to that of the soil nailing method using rebars. As a result of the displacement measurement, the displacement of the high-strength steel pipe is larger than that of the rebars is considered to be the effect of the internal grouting effect of the steel pipe and the decrease in the cross-sectional area. In the case of using high-strength steel pipes for the soil nailing method, it is judged that the field applicability is good by improving stability and workability through member performance and weight reduction.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.93-101
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• 2017

The distribution of inter-annual variation in temperature would help evaluate the likelihood of a climatic risk and assess suitable zones of crops under climate change. In this study, we evaluated two methods to estimate the standard deviation of temperature in the areas where weather information is limited. We calculated the monthly standard deviation of temperature by collecting temperature at 0600 and 1500 local standard time from 10 automated weather stations (AWS). These weather stations were installed in the range of 8 to 1,073m above sea level within a mountainous catchment for 2011-2015. The observed values were compared with estimates, which were calculated using a geospatial correction scheme to derive the site-specific temperature. Those estimates explained 88 and 86% of the temperature variations at 0600 and 1500 LST, respectively. However, it often underestimated the temperatures. In the spring and fall, it tended to had different variance (e.g., increasing or decreasing pattern) from lower to higher elevation with the observed values. A regression analysis was also conducted to quantify the relationship between the standard deviation in temperature and the topography. The regression equation explained a relatively large variation of the monthly standard deviation when lapse-rate corrected temperature, basic topographical variables (e.g., slope, and aspect) and topographical variables related to temperature (e.g., thermal belt, cold air drainage, and brightness index) were used. The coefficient of determination for the regression analysis ranged between 0.46 and 0.98. It was expected that the regression model could account for 70% of the spatial variation of the standard deviation when the monthly standard deviation was predicted by using the minimum-maximum effective range of topographical variables for the area.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.101-108
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• 2005

Adaptive constant false alarm rate(CFAR) algorithm is used for good detection probability as well as constant false alarm rate in clutter background. Especially, filtering technique adaptive to spatial variation is necessary for improving detection quality in non stationary clutter environment which has spatial correlation and large magnitude deviation. In this paper, we propose a two-dimensional block interpolation(TBI) adaptive CFAR algorithm that calculates the node estimate in the fred two dimensional region and subsequently determines the final estimate for each resolution cell by two-dimensional interpolation. The proposed method is efficient for filtering abnormal ejection by adopting distribution median in fixed region and also has advantage of reducing required memory space by using estimation method which gets final values after calculating the block node values. Through simulations, we show that the proposed method is superior to the traditional adaptive CFAR algorithms which are transversal or recursive in aspect of the detection performance and required memory space.

• Journal of The Geomorphological Association of Korea
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• v.18 no.4
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• pp.141-152
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• 2011

The fluctuation of inundation height due to climate change and sea level rise is expected to cause the socio-economical damage in the coastal zone. To evaluate the inundation damage in Haeundae Beach Area, the inundation height was calculated using the observed data and the range of inundated area and buildings was estimated by applying to DEM data, which was constructed with airborne LiDAR data. The range of inundated area and buildings were estimated with 5 scenario of sea level rise in the condition of minimum and maximum inundation height. When the 181cm, the area of 7.19ha and 5 buildings were expected to be inundated. As 20cm in sea level rises at the minimum of the inundation height, the area of 8.90ha and 8buildings were expected to be inundated. As 30cm, 40cm, 50cm, 60cm in sea level rise, 9.98ha and 9 buildings, 11.11ha and 11buildings, 12.41ha and 11buildings, 14.18ha and 14buildings were expected to be inundated, respectively. When the 526 cm, the area of 32.35ha and 42buildings were expected to be inundated. As 20cm, 30cm, 40cm, 50cm, 60cm in sea level rise at the maximum of the inundation height, 38.94ha and 47buildings, 42.46ha and 52buildings, 45.76ha and 58buildings, 49.51ha and 66buildings, 52.53ha and 72buildings were expected to be inundated, respectively. The leisure and industry facilities, socio-economical installation, habitation are located near by the estimated inundation area, then the inundation damage is expected to be greater scale.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.1-11
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• 2012

The equation of the step-drawdown test "$s_w=BQ+CQ^p$" written by Rorabaugh (1953) is suitable for drawdown increased non-linearly in the fractured rocks. It was found that value of root mean square error (RMSE) between observed and calculated drawdowns was very low. The calculated $C$ (well head loss coefficient) and $P$ (well head loss exponent) value of well head losses ($CQ^p$) ranged $3.689{\times}10^{-19}{\sim}5.825{\times}10^{-7}$ and 3.459~8.290, respectively. It appeared that the deeper depth in pumping well the larger drawdowns due to pumping rate increase. The well head loss in the fractured rocks, unlike that in porous media, is affected by properties of fractures (fractures of aperture, spacing, and connection) around pumping well. The $C$ and $P$ value in the well head loss is very important to interpret turbulence interval and properties of high or low permeability of fractured rock. As a result, regression analysis of $C$ and $P$ value in the well head losses identified the relationship of turbulence interval and hydraulic properties. The relationship between $C$ and $P$ value turned out very useful to interpret hydraulic properties of the fractured rocks.