• 대한수학회논문집
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• 제22권2호
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• pp.277-287
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• 2007

We prove that if a graph G of bounded degree has finitely many p-hyperbolic ends($1) in which every bounded energy finite p-harmonic function is asymptotically constant for almost every path, then the set $\mathcal{HBD}_p(G)$ of all bounded energy finite p-harmonic functions on G is in one to one corresponding to $\mathbf{R}^l$, where $l$ is the number of p-hyperbolic ends of G. Furthermore, we prove that if a graph G' is roughly isometric to G, then $\mathcal{HBD}_p(G')$ is also in an one to one correspondence with $\mathbf{R}^l$.

• 산업경영시스템학회지
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• 제23권59호
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• pp.1-10
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• 2000

The traveling salesman problem is a representative NP-Complete problem. It needs lots of time to get a solution as the number of city increase. So, we need an efficient heuristic algorithm that gets good solution in a short time. Almost edges that participate in optimal path have somewhat low value cost. This paper discusses the property of nearest neighbor and 3-opt. This paper uses nearest neighbor's property to select candidate edge. Candidate edge is a set of edge that has high probability to improve cycle path. We insert edge that is one of candidate edge into intial cycle path. As two cities are connected. It does not satisfy hamiltonian cycle's rule that every city must be visited and departed only one time. This paper uses 3-opt's method to sustain hamiltonian cycle while inserting edge into cycle path. This paper presents a highly efficient heuristic algorithm verified by numerous experiments.

• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.164-170
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• 1997

Via hydrosilation-alkenylation approach using hydrosilanes (HSiMeCl2 and HSiCl3) and allylmagnesium bromide with siloxane tetramer (MeCH2=CHSiO)4 as core molecule, noble carbosilane dendrimers with 12, 24, 48 and 96 allylic end groups have been prepared. The reaction path of the repetitive alkenylation and hydrosilation was monitored by means of NMR spectroscopic measurements. Every step for the formation of dendrimer provided almost quantitative yields as pure dendrimers. Based on the observation of UV spectroscopic measurements of Gn (n=1-4) molecules containing allylic end groups, the maximal molal absorption coefficients (εmax) at λmax and the number of double bonds proved an exponentially increased correlation.

• 한국정보과학회논문지:정보통신
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• 제29권4호
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• pp.386-396
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• 2002

본 논문은 신경망을 이용한 최단 경로 문제를 풀기 위해 흡필드 신경망(Hopfield Neural Network)을 변형한 준최적 라우팅 알고리즘(suboptimal routing algorithm)을 다룬다. 이 알고리즘은 기존의 흡필드 신경망 알고리즘과는 달리 뉴런(neuron)의 진화를 위해 모든 주변 뉴런 정보뿐만 아니라, 상관 관계성이 높은 자신의 뉴런 정보도 동시에 이용함으로써, 수렴 성능 및 경로의 최적성을 향상하고자 하였다. 이 알고리즘의 수렴 속도는 흡필드 신경망을 이용하는 기존의 알고리즘보다 더 우수하며, 탐색 경로의 최적성도 높다는 것을 컴퓨터 시뮬레이션을 통해 확인한다. 이 결과는 거의 모든 출발지와 도착지 쌍에 대해 기존의 흡필드 신경망 기반의 최단 경로 탐색 알고리즘에 비해 네트워크 토폴로지에 비교적 덜 민감한 것으로 나타난다. 따라서, mobile ad-hoc network과 같이 네트워크 토폴로지가 시변하는 다중-흡 무선 패킷망(Multi-hop Packet Radio Network)에서의 경로 설정 알고리즘을 구현하는데 유용할 것으로 보인다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.77-81
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• 2002

A new method of optimal blank shape design using the initial nodal velocity (INOV) has been proposed for the drawings of arbitrary shaped cups. With the given information of tool shape and the final product shape, corresponding initial blank shape has been found from the motion of boundary nodes. Although the sensitivity method, the past work of Hynbo Shim and Kichan Son, has been proved to be excellent method to find optimal blank shapes, the method has a problem that a couple of deformation analysis is required at each design step and it also exhibits an abnormal behaviors in the rigid body rotation prevailing region. In the present method INOV, only a single deformation analysis per each design stage is required. Drawings of practical products as well as oil-pan have been chosen as the examples. At every case the optimal blank shapes have been obtained only after a few times of modification without predetermined deformation path. The deformed shape with predicted optimal blank almost coincides with the target shape at every case. Through the investigation the INOV is found to be very effective in the arbitrary shaped drawing process design.

• 소성∙가공
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• 제11권6호
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• pp.487-494
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• 2002

A new method of optimal blank shape design using the initial nodal velocity (INOV) has been proposed for the drawings of arbitrary shaped cups. With the given information of tool shape and the final product shape, corresponding initial blank shape has been found from the motion of boundary nodes. Although the sensitivity method, the past work of the present authors, has been proved to be excellent method to find optimal blank shapes, the method has a problem that a couple of deformation analysis is required at each design step and it also exhibits an abnormal behaviors in the rigid body rotation prevailing region. In the present method INOV, only a single deformation analysis per each design stage is required. Drawings of practical products as well as oil-pan, have been chosen as the examples. At every case the optimal blank shapes have been obtained only after a few times of modification without predetermined deformation path. The deformed shape with predicted optimal blank almost coincides with the target shape at every case. Through the investigation the INOV is found to be very effective in the arbitrary shaped drawing process design.

• 한국항해학회지
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• 제22권3호
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• pp.73-92
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• 1998

Today the number of high school drop-outs is increasing , and also it is serious social problems. But almost factor analyses on the drop-outs are projected by questionnaire. This paper find out by the real data form the concerned documents what factors of drop-outs are. In order to accomplish this study purpose, the methodology are used such as Fequency Analysis, Correlation Analysis, Crosstabulation Analysis. Through the this study this paper could siome suggestions as followings. The first , all education authority should analysis what factors of drop-outs and what drop-out situation is . The second, every teacher should counsel with all problem students sincerely regarding to their characters, future occupations, life course and etc. The third, the most and worst important factors of drop-out is runaway. Because it is very difficult for teacher to teach, lead and guide a runaway student, therefore thepreventino of runaway is efficient for reducing of drop-outs. The fouth, the students violating rules are retrained propoerly in view of guide for good path. The fifth, besides of the above factors. there are drop-out factors such as the health, disease, dafety accidents . All parents. teachers, and students should try their best to solve. To the end, education authority try to encourage teachers to do their role with maximum sense of duty.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.753-760
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• 2007

For protection of the cylinder wall of the ball mill for grinding raw ore. the inner side of the cylinder is covered with rubber liner. The rubber is easily worn down because the rubber relatively soft compared with raw ore. So the rubber liner in the ball mill cylinder must be replaced almost every year and the cost for replacing rubber liner formidable. In this paper, for reducing or excluding the cost of replacing rubber liner the basalt liner is designed. The basalt materials are generally harder than raw ore and the basalt liner in the ball mill does not wear down and so it can be used almost permanently. The concave surfaces are made on the liner of the ball mill and the liner in the cylinder wall plays also the role of raising the steel balls mixed in the raw ore. The section profiles of the concave surface have an important effect on the performance of the ball mill. The deep concave grooves raise the steel balls to high levels and give the large potential energy to the steel balls impacting to the raw ore. But if the concave grooves are too deep. the steel balls raised too high by the concave grooves fly along the parabolic path and reach to the other side of cylinder wall and so the steel balls do not play the roles of grinding the raw ore. The forces acting to a steel ball in a concave groove of the cylinder liner are also analyzed in this paper. The formulas calculating the height and the impact point of the steel ball are introduced and presented. Based to these formulas, the optimum section profiles of the basalt liner are presented.

• 전기학회논문지P
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• 제59권2호
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• pp.191-196
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• 2010

The electricity distribution system in Korea is adopting a multi-grounding system. Protection of this distribution system against lightning is performed by installing overhead ground wires over the high voltage wires, and connecting the overhead ground wires to the ground every 200 m. The ground resistance in this system is limited not to exceed $50\Omega$ and overhead ground wire and neutral wire are multiple parallel lines. Although overhead ground wire and neutral wire are installed in different locations on the same pole, this circuit configuration has duplicated functions of providing a return path for unbalanced currents and protecting the distribution system against induced lightning. Therefore, the purpose of this study is to analyze the induced lightning shielding effect according to the neutral wire installation structure of a 22.9kV distribution line in order to present a new 22.9kV distribution line structure model and characteristics. This study calculated induced lightning voltage by performing numerical analysis when an overhead ground wire is present in the multi-grounding type 22.9kV distribution line structure, and calculated the induced lightning shielding effect based on this calculated induced lightning voltage. In addition, this study proposed and analyzed an improved distribution line model allowing the use of both overhead wire and neutral wire to be installed in the current distribution lines. The result of MATLAB simulation using the conditions applied by Yokoyama showed almost no difference between the induced lightning voltage developed in the current line and that developed in the proposed line. This signifies that shielding the induced lightning voltage through overhead wire makes no difference between current and proposed distribution line structures. That is, this study found that the ground resistance of the overhead wire had an effect on the induced lightning voltage, and that the induced lightning shielding effect of overhead wire is small.

• 한국통신학회논문지
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• 제29권7A호
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• pp.748-755
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• 2004

본 논문에서는 나카가미-m 다중 경로 페이딩 환경에서 MC/DS-CDMA 시스템에 하이브리드 SC/MRC 기법을 적용하여 MRC 기법이 적용된 경우와 비교, 분석하였다. 분석결과. 각 반송파의 입력 다이버시티 가지 수(L)가 3이고 선택된 가지 수( Lc)가 2인 경우 Lc=2 일 때의 MRC 기법보다는 성능이 우수하지만 Lc=3일 때의 MRC 기법을 적용한 경우보다는 성능이 떨어짐을 알 수 있었다. 그러나. 페이딩 지수가 낮을 경우 즉, 환경이 열악해질수록 Lc=3일 때의 MRC 기법과 하이브리드 SC/MRC-(2/3) 다이버시티 기법의 성능이 거의 같음을 확인 할 수 있었고 Lc=4일 때의 MRC 기법과 하이브리드 SC/MRC-(2/4) 다이버시티 기법인 경우도 유사한 성능을 가짐을 확인하였다. 따라서 MC/DS-CDMA 시스템에서 모든 다이버시티 가지에 대해 비트 동기 및 페이딩 진폭, 위상동기를 요구하는 MRC 다이버시티 기법보다는 이를 필요로 하지 않는 SC기법의 장점과 성능이 우수한 MRC 기법의 장점을 이용한 하이브리드 SC/MRC 기법을 적용함으로써 복잡도는 줄이면서 MRC 기법을 사용한 경우의 성능에 근접함을 확인하였다.