• Journal of Korean Society of Transportation
• /
• v.23 no.4 s.82
• /
• pp.31-36
• /
• 2005

Traffic safety evaluation of a city or area on the basis of the accident rate has a limitation that its result is dependent on the characteristics of population. In this paper. we developed a methodology of taking simultaneously the population into account in evaluating the safety, and calculated the traffic safety evaluation index of 25 local governments in the metropolitan area. Based on the result of calculation of the traffic safety evaluation index, it is identified that the proposed approach is able to be an alternative to cooperatively consider various population. The correlation coefficients between the traffic safety evaluation index I(X) which is cooperatively consider the population size and road length, and population based F(P) and road length based F(L) are 0.68 and 0.92 respectively. This means that the proposed approach can overcome the limitation which safety evaluation index are differently calculated according to the characteristics of population. The methodology and traffic safety evaluation index proposed in this paper can be utilized in executing the traffic safety policies for local governments and areas.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.11
• /
• pp.763-770
• /
• 2014

In traditional routing protocols including LEACH for wireless sensor networks, nodes suffer from unbalanced energy consumption because the nodes require large transmission energy as the distance to the sink node increase. Multi-hop based routing protocols have been studied to address this problem. In existing protocols, each cluster head usually chooses the closest head as a relay node. We propose LEACH-CHT, in which cluster heads choose the path with least energy consumption to send data to the sink node. In our research, each hop, a cluster head selects the least cost path to the sink node. This method solves the looping problem efficiently as well as make it possible that a cluster head excludes other cluster heads placed farther than its location from the path, without additional energy consumption. By balancing the energy consumption among the nodes, our proposed scheme outperforms existing multi-hop schemes by up to 36% in terms of average network lifetime.

• Journal of Korea Multimedia Society
• /
• v.14 no.10
• /
• pp.1287-1302
• /
• 2011

Clustering protocol that is used in wireless sensor network is an efficient method that extends the lifetime of the network. However, when this method is applied to an environment in which collected data of the sensor node easily overlap, sensor nodes unnecessarily consumes energy. In the case of clustering technique that uses a threshold, the lifetime of the network is extended but the degree of accuracy of collected data is low. Therefore it is hard to trust the data and improvement is needed. In addition, it is hard for the clustering protocol that uses multi-hop transmission to normally collect data because the selection of a cluster head node occurs at random and therefore the link of nodes is often disconnected. Accordingly this paper suggested a cluster-formation algorithm that reduces unnecessary energy consumption and that works with an alleviated link disconnection. According to the result of performance analysis, the suggested method lets the nodes consume less energy than the existing clustering method and the transmission efficiency is increased and the entire lifetime is prolonged by about 30%.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.2
• /
• pp.281-285
• /
• 2008

Die hobbing is one of the dieblock manufacturing methods of cold forging die, which makes the upper side of dieblock indented using master punch, hobb to produce impression not using cutting work. SKD11, alloy tool steel was used as the material of dieblock and stainless sheet metal was used as product material in cold forging work. The life span of the die was 6,000 strokes. In this research, the material of dieblock was changed into SKH51, the high speed tool steel and the product material was S45C, the carbon steel in the cold forging work. The life span of the die was 21,000 strokes, which is 350% of the life span of the die using the former method.

• Korean Journal of Food Science and Technology
• /
• v.20 no.4
• /
• pp.536-540
• /
• 1988

Effects of blanching time, chemical dipping, freezing method and storage period on texture, color and yield of frozen whole and sliced mushrooms were investigated, and the results are summarized as follows; Frozen whole mushrooms blanched for 5min. had markedly tougher texture than mushrooms blanched for 1 or 2 minutes. As the storage time of frozen mushrooms increased from 3 to 6 months, shear press values increased very significantly. The texture of Freon frozen and plate frozen mushrooms was similar after 3 months storage. Blanching time did not affect texture of frozen sliced mushrooms significantly, but storage time did. The results of sensory evaluation for texture were in good agreement with shear press values. Chemical dipping methods were effective in maintaining desirable color of frozen whole and sliced mushrooms stored for 3 months. The yield of frozen whole mushrooms was significantly increased by shortening blanching time in combination with chemical dipping. Sliced mushrooms required at least 2 min. blanching, to avoid excessive breakage in mechanical slicing operation, for better yield.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.508-508
• /
• 2015

'설계홍수량 산정요령(2012, 국토교통부)'에서 홍수량 산정시 유역면적이 $250km^2$이하의 유역을 하나의 유역으로 처리하여 홍수량을 산정하도록 제시하고 있다. 이는 소유역을 많이 분할하고 하도 홍수추적 및 합성을 통하여 홍수량을 산정할 경우 단일유역에 비해 홍수량이 과대하게 산정됨으로 이에 대한 개선방안으로 제시된 산정요령이다. 홍수량 산정 방법으로 실무에서 가장 많이 사용되고 있고 '설계홍수량 산정요령'에서 채택한 모형인 Clark 단위도법에 의한 방법으로 산정된 홍수량의 크기에 미치는 민감도가 도달시간보다 저류상수가 훨씬 크므로 합리적인 저류상수 결정방법이 매우 중요하다. 저류상수를 결정하는 방법에는 여러 가지 경험공식이 적용되고 있으며 그 중 '설계홍수량 산정 요령(2012, 국토교통부)'에서는 유역면적이나 유역형상 등을 고려하고 있는 Sabol 공식을 적용하도록 하고 있다. Sabol 공식은 유역형상계수에 의해 많은 영향을 받으며, 유역형상계수는 형상이 흐름방향으로 길쭉한지 넓적한지를 나타내는 지표로서 유역 평균폭을 본류 연장으로 나눈 값으로 정의되며, 통상 유역면적을 본류 유로연장의 제곱으로 나타낸다. 따라서 유역의 형상이 폭에 비해 길면 형상계수가 1보다 작아지며 반대로 길이에 비해 폭이 넓거나 형상이 둥글면 형상계수는 1에 근접하며, 일반적으로 우리나라 하천의 형상계수는 대부분 약 0.5~0.1 정도의 범위를 나타내고 있다. 그러나, Sabol공식을 적용하여 저류상수를 산정할 경우 유역형상계수가 극히 작을 경우 홍수량이 과소하게 산정되므로 적절한 유역분할을 통해 홍수량을 보정할 필요가 있다. 따라서, 미호천 권역에서 유역형상계수가 0.1 이하인 유역을 대상으로 단일유역으로 산정한 홍수량과 적절한 유역 분할 후 홍수량을 산정하여 비교하고 비슷한 규모의 인근유역의 홍수량과 기산정된 홍수량을 비교하여 유역형상계수 0.1이하에서의 적절한 소유역 분할 기준을 제시하여 홍수량이 과대 및 과소하게 산정되지 않도록 조정하는데 있다.

• The Journal of Engineering Geology
• /
• v.29 no.3
• /
• pp.329-337
• /
• 2019

Bottled water companies in Korea are required to conduct an environmental impact assessment of their drinking water supply at least six months before the expiration of their five-year marketing and production license. The water level drawdown, production well water quality, and monitoring well observation results are the most important items that are evaluated in the assessment report. Here we evaluate the relationship between well drawdown and pumping capacity with pumping time from the production wells of bottled water manufacturers located in Cretaceous granite (site A) and Precambrian gneiss (site B). The method to reduce the pumping capacity is more effective in decreasing the drawdown than the method to simultaneously control the pumping and recovery times. Furthermore, the monitoring data from the pH monitoring sensors that were installed in Precambrian gneiss (site C) yield pH values that increase with time and eventually plateau at a certain value. We therefore propose that pH monitoring is either discontinued or improved to provide more reliable and usable results.

• Journal of Korea Multimedia Society
• /
• v.12 no.11
• /
• pp.1609-1622
• /
• 2009

In wireless sensor networks, a clustering protocol is an efficient method to prolong network lifetime. In general, it results in more energy consumption at the cluster-head node. Hence, such a protocol must changes the cluster formation and cluster-head node in each round to prolong the network lifetime. But, this method also causes large amount of energy consumption during the set-up process of cluster formation. In order to improve energy efficiency, in this paper, we propose a new clustering algorithm. In this algorithm, we exclude duplicated data of adjacent nodes and transmits the threshold value. We define a group as the sensor nodes within close proximity of each other. In a group, a node senses and transmits data at a time on the round-robin basis. In a view of whole network, group is treated as one node. During the setup phase of a round, intra clusters are formed first and then they are re-clustered(network cluster) by choosing cluster-heads(group). In the group with a cluster-head, every member node plays the role of cluster-head on the round-robin basis. Hence, we can lengthen periodic round by a factor of group size. As a result of analysis and comparison, our scheme reduces energy consumption of nodes, and improve the efficiency of communications in sensor networks compared with current clustering methods.

• Journal of Korea Multimedia Society
• /
• v.11 no.8
• /
• pp.1082-1092
• /
• 2008

In wireless sensor networks, clustering protocol such as LEACH is an efficient method to increase whole networks lifetime. However, this protocol result in high energy consumption at the cluster head node. Hence, this protocol must changes the cluster formation and cluster head node in each round to prolong the network lifetime. But this method also causes a high amount of energy consumption during the set-up process of cluster formation. In order to improve energy efficiency, in this paper, we propose a new cluster formation algorithm. In this algorithm, we define a intra cluster as the sensor nodes within close proximity of each other. In a intra cluster, a node senses and transmits data at a time on the round-robin basis. In a view of whole network, intra cluster is treated as one node. During the setup phase of a round, intra clusters are formed first and then they are re-clustered(network cluster) by choosing cluster-heads(intra clusters). In the intra cluster with a cluster-head, every member node plays the role of cluster-head on the round-robin basis. Hence, we can lengthen periodic round by a factor of intra cluster size. Also, in the steady-state phase, a node in each intra cluster senses and transmits data to its cluster-head of network cluster on the round-robin basis. As a result of analysis and comparison, our scheme reduces energy consumption of nodes, and improve the efficiency of communications in sensor networks compared with current clustering methods.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.751-756
• /
• 1998

고리 1호기 원전 수명 연장을 위한 가압열충격(Pressurized Thermal Shock : PTS) 해석은 확률론적 안전성 평가 방법에 따라 수행된다. 본 연구는 가압열충격 상세 해석 연구의 일환으로 가압열충격 해석을 위한 계통해석시 사용되는 최적 평가(Best Estimate) 방법과 기존의 PCT(Peak Cladding Temperature) 관점의 해석에 사용되는 결정론적 안전성 평가 방법간의 해석 방법론 차이에 의한 열수력 거동의 상이점을 평가하기 위함이다. 이를 위해 1998년 설치 예정인 고리 1호기 교체 증기발생기(Replacement Steam Generator ; RSG) 안전성 분석 보고서$^{[1]}$ 의 주증기관 파단사고 해석 결과와 동일한 파단 크기 및 운전 출력에 대해 최적 평가 방법론에 따라 해석된 본 연구의 해석 결과를 비교, 평가하였다. 해석 결과 전출력 소형 주증기관 파단 사고에서는 터빈 유량 모델링 및 반응도 계수, 고온 영출력 대형 파단 사고에서는 가압기 모델, 반응도 계수 및 정지여유도가 해석 방법론에 따른 열수력 거동의 차이에 영향이 큰 것으로 평가되었다