• 한국표면공학회지
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• 제43권2호
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• pp.80-85
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• 2010

The surfaces of WC-Co and SCM415 were etched to form a micro size protrusion for oil based ultra low friction applications using an ion bombardment process in a filtered vacuum arc plasma. WC-Co species showed that a self-patterned surface was available by the ion bombarding process due to the difference of sputtering yield of WC and Co. And the increasing rate of roughness was 0.6 nm/min at -600 V substrate bias voltage. The increasing rate of roughness of SCM415 species was 1.5 nm/min at -800 V, but the selfpatterning effect as shown in WC-Co was not appeared. When the SCM415 species pretreated by electrical discharge machining is etched, the increasing rate of roughness increased from 1.5 nm/min to 40 nm/min at -800 V substrate bias voltage and the uniform surface treatment was available.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.67-75
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• 2007

This study intends to the adequacy inspection of the room temperature variation rate that is available in the building heat performance evaluation index, so we performed the sensitivity analysis about the room temperature variation rate and the energy consumption in the room. For these purpose, we supposed the models which are composed of the various window area, insulation thickness and ventilation rate. Then we analyzed the simulation using the ESP-r and Seoul weather data. In this research, the pattern of the increasing & decreasing rate of annual load according to the change of the various design factors is similar to the pattern of increasing & decreasing rate of not the K-values but the room temperature variation rate. Also we derive the optimum value of the various design factors and the room temperature variation rate in this analysis model. Further study is to be required the development of convenient tool to use in the real design.

• 전자공학회논문지S
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• 제35S권7호
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• pp.14-21
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• 1998

In providing with low speed multimedia services, a call blocking rate is greatly varied according to the transmission rate, and thereofr, the call blocking rate is remarkably increased for a service having a high transmission rate compared to a service having a low transmission rate. This paper presents three methods of solving this problem; Packing Scheme in which available channels distributed to each frequency channel are concentrated on one frequency channel and a call having a high transmission rate is assigned to the frequency channel; Queuing Scheme in which queuing is assigned to calls under service is temporarily reduced and a call having a high transmission rate is allowed. The result of performance analysis for 13 Kbps and 128 Kbps service through computer simulation showed that the call blocking rate for 128 Kbpx service was reduced by tens of percent accoring to loads.

• 한국토양비료학회지
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• 제32권3호
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• pp.261-267
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• 1999

본 연구는 인이 축적된 토양을 대상으로 작물 연속 재배에 따른 토양 유효 인 함량의 경시적 변화를 고찰함은 물론 이를 근거로 하여 인이 축적된 토양이 작물생장 적정 수준 이상의 인을 공급할 수 있는 기간을 예측하여 토양에 축적된 인의 효율적 이용에 기여하고자 수행되었다. 공시 토양은 인이 과잉 집적됨으로써 10% 미만의 시비인 회수율을 보였으며, 인 무처리구의 작물 생산량은 추천시비량을 시비한 경우의 88% 이상으로 나타나 시비 수준에 따른 작물체 생장 차이는 없었던 것으로 판단할 수 있었다. 인산질 비료를 무시비한 상태에서 연속 4회 작물 재배한 후에도 토양 유효인은 여전히 높은 수준 (Bray 1-P : $410{\sim}610mg\;P\;kg^{-1}$, Olsen-P : $284{\sim}401mg\;P\;kg^{-1}$, Lancaster-P : $368{\sim}524mg\;P\;kg^{-1}$, 가용성인: $37{\sim}55mg\;P\;kg^{-1}$)을 유지하였다. 토양 유효인의 감소량과 작물에 의해 흡수된 인 사이에는 유의성있는 상관관계 (Bray 1-P : $R^2=0.536^{**}{\sim}0.761^{**}$, Olsen-P : $R^2=0.642^{**}{\sim}0.774^{**}$, Lancaster-P : $R^2=0.513^{**}{\sim}0.797^{**}$)가 있었다. Soil 1 유효인 감소량(y)과 작물흡수한 인(x) 사이에 상관식은 다음과 같았다. Bray 1-P : y = 149.7x + 102.7 Lancaster-P : y = 209.2x-140.2 Olsen-P : y = 260.8x + 19.9 인 무처리구 토양의 유효인 함량(C)이 작물 재배회수(N)에 따라 감소하는 경향은 1차 반응 속도 방정식으로 나타낼 수 있었으며, 이 식을 통해서 유효인이 초기함량의 절반이나 인 유효도 한계 치까지 감소하는 데 소요되는 작물 재배 회수를 예측할 수 있었다. Soil 1의 유효인 감소 속도 방정식은 다음과 같았다. Bray 1-P : In(C) = -0.12N + 6.96 r=-0.991, Lancaster - P : In(C) = -0.14N + 6.88 r=-0.938. Olsen-P : In(C) = -0.07N + 6.37 r=-0.959.

• Geomechanics and Engineering
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• 제13권6호
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• pp.963-975
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• 2017

Improvement of soft clay deposit by preloading with vertical drains is one of the most popular techniques followed worldwide. These drains accelerate the rate of consolidation by shortening the drainage path. Although the analytical and numerical solutions available are mostly based on equal strain hypothesis, the adoption of free strain analysis is more realistic because of the flexible nature of the imposed surcharge loading, especially for the embankment loading used for transport infrastructure. In this paper, a numerical model has been developed based on free strain hypothesis for understanding the behaviour of soft ground improvement by vertical drain with preloading. The unit cell analogy is used and the effect of smear has been incorporated. The model has been validated by comparing with available field test results and thereafter, a hypothetical case study is done using the available field data for soft clay deposit existing in the eastern part of Australia and important conclusions are drawn therefrom.

• 한국의학물리학회지:의학물리
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• 제31권2호
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• pp.9-19
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• 2020

Purpose: This study aims to develop a multi-purpose electron beam irradiation device for preclinical research and material testing using the research electron linear accelerator installed at the Dongnam Institute of Radiological and Medical Sciences. Methods: The fabricated irradiation device comprises a dual scattering foil and collimator. The correct scattering foil thickness, in terms of the energy loss and beam profile uniformity, was determined using Monte Carlo calculations. The ion-chamber and radiochromic films were used to determine the reference dose-rate (Gy/s) and beam profiles as functions of the source to surface distance (SSD) and pulse frequency. Results: The dose-rates for the electron beams were evaluated for the range from 59.16 Gy/s to 5.22 cGy/s at SSDs of 40-120 cm, by controlling the pulse frequency. Furthermore, uniform dose distributions in the electron fields were achieved up to approximately 10 cm in diameter. An empirical formula for the systematic dose-rate calculation for the irradiation system was established using the measured data. Conclusions: A wide dose-rate range electron beam irradiation device was successfully developed in this study. The pre-clinical studies relating to FLASH radiotherapy to the conventional level were made available. Additionally, material studies were made available using a quantified irradiation system. Future studies are required to improve the energy, dose-rate, and field uniformity of the irradiation system.

• 한국토양비료학회지
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• 제45권1호
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• pp.86-92
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• 2012

To promote the practical use of livestock manure compost (LC) for paddy rice cultivation, the fertilization efficiency of nutrients in LCs was investigated compared to that of chemical fertilizer. This experiment was conducted at rice field in Hwaseong, Korea, with 6 treatments by each of 3 kinds of tested LCs, cattle manure compost (CaC), swine manure compost (SwC) and chicken manure compost (ChC). The treatments consisted of 3 application levels of LCs and 3 chemical fertilizer treatments having the same application levels with LCs. $NH_4$-N content in soil became higher according to the increase in the urea application rate, while it became lower in LC plots than in urea plots, and statistically had no significant difference among LC plots. There was a close relationship between phosphate fertilization rate and the increment of soil available phosphate content after experiment resulting y = 0.1788x - 6.169 ($R^2=0.9425$) when applied fused superphosphate fertilizer, and y = 0.0662x - 2.689 ($R^2=0.9315$) when applied LC at the equivalent rates to phosphate input (x: phosphate application rate, kg $ha^{-1}$, y: increment in soil available phosphate content, mg $kg^{-1}$). And from these two equations, the correlation on the phosphate application rate between fused superphosphate fertilizer and LC could be obtained as y = 2.7056x - 52.492 (x: $P_2O_5$ application rate of fused superphosphate, kg $ha^{-1}$, y: $P_2O_5$ application rate of LC, kg $ha^{-1}$). Plant height, number of tillers, nutrients uptake by rice, and rice yield showed higher levels in N 100% and N 150% application plots of chemical fertilizers, while every LC plots exhibited lower values and no significant difference among them. Relative nitrogen fertilization efficiencies of LCs compared to urea was 12.3% for CaC, 8.8 for SwC and 24.6 for ChC, respectively.

• 디지털콘텐츠학회 논문지
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• 제9권3호
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• pp.433-439
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• 2008

온라인 게임에서 동영상은 게임을 홍보하는 중요한 수단이며, 게임 진행에 많은 도움을 준다. 이 경우에 동영상은 저장 공간의 효율적인 사용과 네트워크 자원의 효율성을 위해 가변 비트율 형태로 압축된다. 적응형 대역폭 할당은 게임 동영상에 대한 전송 계획을 세우고 이 계획에 의한 전송률이 가용 전송률보다 큰 경우에 가용 전송률을 만족시킬 때까지 일부 프레임을 폐기시켜서 전송하는 방법이다. 이때, 적응형 대역폭 할당 방법에서의 평가 요소들은 전송률을 설정하는데 크게 영향을 준 프레임들의 폐기 순서에 따라 크게 달라질 수 있다. 본 논문에서는 이를 살펴보기 위하여 전송 계획에 사용되는 CBA, MCBA, MVBA, [6]], [7]의 알고리즘들을 적응형 대역폭 할당 방법의 전송 계획으로 각각 적용하여 다양한 프레임 폐기 방법들로 성능을 평가한다.

• 한국정보처리학회논문지
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• 제4권10호
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• pp.2605-2614
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• 1997

최근 고속 데이터 서비스에 대한 수요가 증대됨에 따라 이를 위한 효율적인 서비스에 대한 관심이 집중되고 있다. ATM 망에서는 고속전송과 트래픽 다중화를 하기 때문에 반응제어 보다는 예방제어에 중점을 두고 있으나, 망 내에서 데이터 트래픽의 예측할 수 없는 통계적 흐름과 버스등환 특성은 망에 제공되는 서비스 품질을 떨어뜨리고 과잉 밀집에 의해 폭주가 발생할 수 있다. 따라서 반응적 제어 방법이 연구되어 왔다. 특히 ATM Forum에서는 새로운 ATM 서비스인 ABR(Available Bit Rate) 서비스의 트래픽 관리에 대한 표준화를 위해 많은 노력을 기울였다. ABR트래픽은 현재 셀의 상태 정보와 더불어 feedback 된 정보를 사용하여 트래픽 흐름을 제어하므로 사용자에게 체계적이고 동적으로 대역을 할당할 수 있게 되었다. 본 논문에서는 최근 ATM Forum에서 ABR 트래픽을 지원하는 방식으로 채택된 Rate 기법에 이중 임계치 버퍼 개념을 적용하여 ABR 트래픽 전송시의 성능 향상 기법을 제안하였다. 이중 임계치 버퍼는 버퍼내에 2개의 임계치를 설정하여 전송율 조절을 2곳에서 가능하게 한다.

• 한국연초학회지
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• 제6권2호
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• pp.155-168
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• 1984

Field test were conducted to select the best method for soil phosphorus test and to obtain the critical levels of each method for P fertilizer recommendations based on tobacco production. Truog method was recognized to be the mort suitable one for soil P test. N. Carolina, Bray No.1 and Olsen methods were followed in order. Bray No. 2 and Lancaster methods showed the least satisfaction. The critical levels of available P by lancaster, Bray No. 1, N. Carolina,01sen, and Truog methods were 55ppm, 32ppm, 21ppm, 19ppm, and 22ppm, respectively. Below the critical level a large yield response can be expected with 10kg $P_2O_5$/10a, above critical level little or no response is expected. In soils the more the initial available p, the more available P was carried over, while the more the total amount of silt and clay, the less the residual P was found. The increase in residual P by 10kg of $P_2O_5$ was greater than that of 5kg/10a. The chemical composition and the price of the cured leaf were not affected by the $P_2O_5$ application, indicating that the increase in the rate of $P_2O_5$ application would not exert on the quality of tobacco.