• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.108-108
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• 2018

상수관의 노후화 혹은 공사 중 작업자의 실수, 또는 자연재해 등에 의해 상수관망 내 파손 관이 발생할 경우 파손된 관의 보수 및 교체 작업을 위해서는 파손 관과 인접한 밸브를 차폐하게 된다. 이로 인하여 관망의 일부 지역에 물 공급이 차단되는 단수구역이 발생하게 되며, 단수구역은 밸브를 닫음으로 인해 파손 관과 함께 격리되는 직접고립지역(segment)과 직접고립지역을 차폐함으로써 의도치 않게 수원으로부터 물 공급이 차단되는 간접고립지역(unintended isolation)으로 구분할 수 있다. 간접고립지역은 차폐된 직접고립지역으로 인해 수원으로부터의 유일한 용수공급 노선이 차단되어 발생한다. 관 파손에 의한 단수 피해를 현실적으로 모의하기 위해서는 밸브위치에 따른 단수구역을 정확히 산정할 필요가 있다. 단수구역은 파손관의 위치뿐만 아니라 차단 밸브의 개수 및 위치에 따라 달라진다. 따라서, 관 파손에 의한 단수피해를 최소화하기 위해서는 각 관로의 파손확률과 절점의 중요도를 고려하여, 적절한 밸브의 위치를 선정해야 한다. 본 연구에서는 관 파손에 따른 단수상황을 모의하여 파손 관에 의한 직, 간접 단수구역을 탐색한 후, 단수용량을 파악하고 이를 최소화하기 위한 밸브의 적정 위치를 최적화 알고리즘을 이용하여 결정하는 방안을 제시하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.6
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• pp.71-80
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• 2005

In the near future, various aplications on the Internet will be based on the multicast group communication, so that the efficient group key management is essential for managing the frequent group join and leave events. In this paper, we propose several batch rekeying schemes extended from conventional individual rekeying schemes, and analyze the efficiencies of them in terms of both the number of encryption and one-way hash function as well as multicast message size. Considering multiple member leaves, a probabilistic approach is need to compute the average computational amounts for rekeying.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.696-698
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• 2022

게임에서는 장애물이 가로 막고 있을 때 길 찾기 알고리즘이 요구된다. Path Finding Method 는 길과 장애물을 고려하여 목적지까지의 경로를 찾는 방법을 말한다. A^* 알고리즘은 이런 복잡한 미로 찾기에 최적화된 Path Finding 알고리즘이다. 하지만, 모바일 같은 저비용 기기에서 A^* 알고리즘을 사용하기엔 단순한 지형에서도 연산 부하가 발생할 수 있다. 본 논문에서는 가상의 공간에서 Grid를 구축하여, 통행이 가능한 곳과 불가능한 곳을 나누어 최종 지점에 도달할 수 있도록 하는 방식을 제안한다. 본 논문에서 제시한 Path Finding Method 는 최종 지점이 막다른 길인 경우 가장 가까운 이동 가능한 경로로 길을 안내하도록 설계하여 예외 상황에 대처했다. 대표적인 길 찾기 알고리즘인 Dijkstra 알고리즘은 최소 비용을 고려해서 최단으로 가는 거리를 비교하여 길을 나타낼 수 있다. 하지만, Dijkstra 알고리즘 경우 비용이 양수가 아닌 음수의 경우 무한 루프에 빠지는 등 결과 값이 제대로 나오지 않을 수 있다. 본 논문에서 제안한 Path Finding Method 는 최소 비용을 노드별로 비교하는 방식이 아닌 초기 비용을 알 수 없는 분야에 쉽게 사용할 수 있다. 본 논문에서는 제안한 Path Finding Method 를 적용하여 Web 게임을 제작하는 것에 성공하였다. 향후, Path Finding Method 결과에 위치 정렬 알고리즘을 적용하여, 중복된 지역을 가는 확률을 최소화하면서 정리된 Path 가 돌출되도록 연구할 예정이다. 본 논문의 Path Finding Method 은 게임 개발 분야에 적극 기여되길 바란다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.15-17
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• 2022

In order to minimize surplus parts in ball bearing selective assembly systems, it is necessary to optimize the selection probability by grasping the dimensional distribution of each part. But the use of a complex system causes delays in the production process. In this paper, we propose cluster priority selection algorithm that can quickly and simply determine the selection priority in ball bearing selective assembly system. In addition, we assume the simulated situation with the data collected in the actual ball bearing selective assembly process, and evaluate the incidence of surplus part and runtime by simulating the cluster priority selection algorithm and the exiting algorithm. As a result of the simulation, the cluster priority selection algorithm generated 83.8% less surplus parts, and 39.7% less runtime than the existing algorithm.

• Journal of Space Technology and Applications
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• v.3 no.2
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• pp.118-143
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• 2023

Space is becoming more commercialized. Despite of its delayed start-up, space activities in Korea are attracting more nation-wide supports from both investors and government. May 25, 2023, KSLV II, also called Nuri, successfully transported, and inserted seven satellites to a sun-synchronous orbit of 550 km altitude. However, Starlink has over 4,000 satellites around this altitude for its commercial activities. Hence, it is necessary for us to constantly monitor the collision risks of these satellites against resident space objects including Starlink. Here we report a quantitative research output regarding the conjunctions, particularly between the Nuri satellites and Starlink. Our calculation shows that, on average, three times everyday, the Nuri satellites encounter Starlink within 1 km distance with the probability of collision higher than 1.0E-5. A comparative study with KOMPSAT-5, also called Arirang-5, shows that its distance of closest approach distribution significantly differs from those of Nuri satellites. We also report a quantitative analysis of collision-avoiding maneuver cost of Starlink satellites and a strategy for Korea, being a delayed starter, to speed up to position itself in the space leading countries. We used the AstroOne program for analyses and compared its output with that of Socrates Plus of Celestrak. The two line element data was used for computation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1A
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• pp.25-33
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• 2003

We derive the outage probabilities for the Erlang capacity and link margin based on handoffs in the reverse link of a CDMA system of 14.4 kbps/1.9 GHz band, calculate them with the same parameters, and then with the maximum realizable Erlang capacity analyze newly the cell coverage in different areas by the COST-231 model If it decreases from 5 % to 2 % in case of $E_b/N_0$=5 dB under a soft handoff, the result shows a very reliable link with additional increment of 0.88 dB in the margin and a high quality of service within the coverage decrease of 0.12 km, 0.25 km, and 1 km in a city, suburban, and open areas respectively on the decrease of 2 Erlang in the capacity. When the $E_b/N_0$ decreases from 7 dB to 5 dB within the outage probability of 5 %, it shows the increase of 9 Erlang and of 0.2 km in a city on the same margin of 2.8 dB. Then, comparing it with a single cell, it shows the decrease of more than 10 Erlang in the capacity, but the enlargement of 0.17 km, 0.3 km, and 1 km in them on the margin decrease of 1.31 dB, also, with a hard handoff, the soft handoff gain of the increase of 10 Erlang and of 0.22 km, 0.5 km, and 2 km on the decrease of 2.16 dB.

• Korea journal of population studies
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• v.35 no.2
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• pp.55-72
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• 2012

Few studies have done on the intergenerational relations of married women and their own parents in Japan. This study approaches the topic by examining coresidence and contact frequency between generations. The study expects the likelihood of living together (including living next door) and the extent of contact would differ by the characteristics of woman, her husband, children, her brothers and sisters, her own parents and parents-in-law. From the 2003 Survey for National Family Research in Japan, selected are 853 currently married women in their 30s and 40s whose parent and parents-in-law are alive. The analysis shows that the likelihood of living together with parents decreases as the number of brothers and sisters increases. In particular, the presence of brother substantially decreases the likelihood. Having father only alive (vs. having both parents alive) also increases the likelihood. The frequency of contact with parents is conditioned by the coresidence with parents-in-law. It also differs by the level of education and its gap between spouses. Subjective evaluation of husband's attitude toward her parents is important. As in the case of living together, the number of brothers and sisters and the survival status of parents are significant in explaining the frequency of contact with her parents. The results indicate that number of brothers and sisters as well as widowhood of parents serves as its demographic condition. The findings that the frequency of contact with parent are affected by coresidene with parents-in-law, education gap between spouses and husband's attitude toward her parents suggest that the relationship of married women with her own parents are conditioned by her husband and his parents.

• Journal of Navigation and Port Research
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• v.47 no.1
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• pp.1-9
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• 2023

Many studies have analyzed marine accidents, and since marine accident information is updated every year, it is necessary to periodically analyze and identify the causes. The purpose of this study was to prevent accidents by identifying and analyzing the causes of marine accidents using previous and new data. In marine accident data, 1,921 decisions by the Korea Maritime Safety Tribunal on marine accidents on fishing ships over 16 years were collected in consideration of the specificity of fishing ships, and 1,917 cases of accident notification text history by the Ministry of Maritime Affairs and Fisheries over 3 years were collected. The decision data and text data were classified according to variables and quantified. Prior probability was calculated using a Bayesian network using the quantified data, and fishing ship marine accidents were predicted using backward propagation. Among the two collected datasets, the decision data did not provide the types of fishing ships and fishing areas, and because not all fishing ship accidents were included in the decision data, the text data were selected. The probability of a fishing ship marine accident in which engine damage would occur in the West Sea was 0.0000031%, as calculated by backward propagation. The expected effect of this study is that it is possible to analyze marine accidents suitable for the characteristics of actual fishing ships using new accident notification text data to analyze fishing ship marine accidents. In the future, we plan to conduct research on the causal relationship between variables that affect fishing ship marine accidents.

• Korean Journal of Acupuncture
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• v.24 no.1
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• pp.13-25
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• 2007

목 적 : 흡연에 따른 건강적 피해가 많이 알려져 있음에도 불구하고 특히 여성 및 청소년 계층의 흡연이 증가하고 있으며 폐암 사망자수는 급격히 늘어나고 있는 상황이다. 완전한 금연이 실패하는 주요 이유는 담배의 중독성에서 비롯되며 금단현상을 극복하지 못해 일어나는 것으로 알려져 있다. 흡연의 중독성은 담배 주요성분 중의 하나인 니코틴(nicotine)에 의해 유발되며 따라서 모든 금연 요법 및 금연 치료보조제 들은 이 니코틴 작용을 어떻게 효과적으로 억제 또는 대체하느냐에 초점을 맞추고 있다. 최근 금연치료 요법으로 한방 침이 주목 받고 있으며 본 논문을 통해 한방 침의 금연효과에 대한 신경학적 기전을 고찰하고자 한다. 방 법 : 금연을 돕는 전형적인 보조 치료제 및 치료법이 몇 종류 개발되어 사용 중에 있으며 대표적으로 니코틴 대체 요법(nicotine replacement therapy, NRT)이나 항우울제로 사용되는 bupropion 등을 들 수 있다. 이 치료 방법들은 뇌의 도파민계 신경전달 체계에 영향을 미쳐 금연 효과를 발휘하게 되는데 실질적인 금연성공확률은 그리 높지 않은 것으로 알려져 있다 따라서 침의 자극에 대한 도파민계 신경전달 조절효과를 중심으로 고찰함으로써 침의 금연효과에 대한 의과학적 기전을 설명하고자 하였다. 결 과 : 침자극은 우수한 금연효과를 가져올 수 있는 치료법으로 기존의 금연 치료요법 및 치료제 들을 보완할 수 있는 보다 확실한 치료요법 중의 하나이며 특히 금연 후에 오는 금단현상을 효과적으로 완화시키는 작용을 한다. 그리고 이 같은 효과는 부분적으로 도파민계를 비롯한 신경전달계를 조절함으로써 가능한 것으로 판단된다. 결 론 : 본 논문을 통해 니코틴에 의한 금단현상의 신경학적 기전과 금연과 관련된 신경전달체계에 대한 침자극의 효능에 대해 고찰하였으며 기존의 금연보조치료법을 대체할 수 있는 우수한 의학적 치료법으로써의 침치료법을 제시하였다.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.303-317
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• 2020

The purpose of this study is to conceptualize the process of formation by the exploration of the lives of professional golfers who grow to excellent sports leaders, categorize the concept and suggest models between categories. In order to reveal in depth the change process of the job formation, the 'grounded approach' as a qualitative study was used as a the methodological frame of this study, and snow sampling, one of nonrandom sampling was used for the selection method of the study participants. 10 study participants who are able to make positive self-expression and talk with the researcher were selected. Through grounded approach appropriate for this process research, this study could acquire following results. First, through the casual condition that is the exploration of the lives of professional golfers growing to excellent sports leaders, it connected to the central phenomena of professional instruction methods and education belief as golf leaders. In this process, the changes as new experiences for the charm of the new job and relationship formation influence as the function of a contextual condition. In addition, golf leaders tried to become a more completed golf leader through self-efforts for development and expertise attainment according to the their own situations as well as belief, and they have established the lives of firm golf leaders through the process. Second, as a result of the changes of their lives as professional golfers growing to excellent sports leaders, the paradigm of grounded approach which is abstracted as total 141 concepts, 17 subcategories, and 11 superordinate categories were composed.