• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.185-191
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• 2023

To the exact cover problem that remains NP-complete to which no polynomial time algorithm is made available, this paper proposes a linear time algorithm that yields an optimal solution. The proposed algorithm makes use of the set cover problem's major feature which states that "no identical element shall be included in more than one covering set". To satisfy this criterion, the proposed algorithm initially selects a subset with the minimum cardinality and deletes those that contain the cardinality identical to that of the selected subset. This process is repeatedly performed on remaining subsets until the final solution is obtained. Provided that the solution is unattainable, it selects subsets with the maximum cardinality and repeats the same process. The proposed algorithm has not only obtained the optimal solution with ease but also proved its wide applicability on N-queens problems, hence disproving the NP-completeness of the exact cover problem.

• The Journal of the Korean dental association
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• v.41 no.8 s.411
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• pp.552-557
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• 2003

치아 삭제의 원리 중 변연과 관련된 조건들과 다양한 보철물 마무리에 따른 특성을 살펴보고 완전 도재관의 변연 각도에 따른 적합도와 응력분포에 대한 실험 결과를 참고해 적절한 변연 디자인 선택시에 도움이 되고자 한다. 성공적인 보철물 변연은 마무리선에 정확히 맞아야하는 fitness(cement의 노출 최소), 환자와 술자의 입장에서 청결 가능한 부위에 위치되어야 하는 location, 그리고 교합력에 충분히 저항할 수 있는 stress를 만족할 수 있어야 할 것이다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.234-237
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• 2003

SPKI 권한 인증서를 이용한 기존의 방식은 각 사용자마다 임의적으로 인증서를 발행할 수 있기 때문에 상위객체에 접근권한이 불가능한 데이터에도 접근권한을 줄 수 있다. 그래서 중요한 문서에 대한 보안이 완전하지 못하다. 따라서 본 논문에서는 강제적 접근제어 모델을 기반으로 하여 서버에서 보안레벨에 따라 등급을 나누고 인증서 내에 접근권한을 명시해 줌으로써 접근권한을 추가하거나 삭제할 수 있다. 이는 강제적 모델에 유연성을 제공해주고 서버에서 하는 역할을 줄일 수 있으며, 높은 등급의 정보가 낮은 등급의 객체로 흐르는 것을 막아주므로 기존의 방식보다 좀 더 안전한 접근제어 메커니즘을 제공한다. 또한, 서버에서 XML로 접근제어 레벨을 정의해주므로 여러 플랫폼에서 사용 가능한 이점을 지닌다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.263-269
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• 2014

In this paper, I disprove Hadwiger conjecture of the vertex coloring problem, which asserts that "All $K_k$-minor free graphs can be colored with k-1 number of colors, i.e., ${\chi}(G)=k$ given $K_k$-minor." Pursuant to Hadwiger conjecture, one shall obtain an NP-complete k-minor to determine ${\chi}(G)=k$, and solve another NP-complete vertex coloring problem as a means to color vertices. In order to disprove Hadwiger conjecture in this paper, I propose an algorithm of linear time complexity O(V) that yields the exact solution to the vertex coloring problem. The proposed algorithm assigns vertex with the minimum degree to the Maximum Independent Set (MIS) and repeats this process on a simplified graph derived by deleting adjacent edges to the MIS vertex so as to finally obtain an MIS with a single color. Next, it repeats the process on a simplified graph derived by deleting edges of the MIS vertex to obtain an MIS whose number of vertex color corresponds to ${\chi}(G)=k$. Also presented in this paper using the proposed algorithm is an additional algorithm that searches solution of ${\chi}^{{\prime}{\prime}}(G)$, the total chromatic number, which also remains NP-complete. When applied to a $K_4$-minor graph, the proposed algorithm has obtained ${\chi}(G)=3$ instead of ${\chi}(G)=4$, proving that the Hadwiger conjecture is not universally applicable to all the graphs. The proposed algorithm, however, is a simple algorithm that directly obtains an independent set minor of ${\chi}(G)=k$ to assign an equal color to the vertices of each independent set without having to determine minors in the first place.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.24 no.2
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• pp.122-133
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• 2015

The requirements for the successful treatment of all-ceramic restorations are not so different from the ones of conventional restorations. "The provisional restoration followed by an adequate tooth reduction" and "the accurately fitting prostheses with corresponding to final impression" can be the examples of them. Nevertheless, the one which all-ceramic restorations are distinguished from conventional restorations is the additional procedure of so called "bonding". In addition to the application of resin cement between "inner surface of restoration and outer surface of abutment", bonding technology can be also applied to the treatment process of "Post and Core" in particular if the abutments are non-vital teeth. Core build-up for all-ceramic crown is conducted with fiber post and tooth colored composite by considering the properties of the restorations transmitting light. We know well that a vital abutment is easier than a non-vital one to get the targeted goals for clinical success in connection with esthetics and structure. The creation of "Post and Core" with bonding technique is a decisive factor for a long-term success if the abutment is non-vital tooth with dentinal collapse. I would like to share my clinical experience about "post & core build-up and all-ceramic restoration bonding" out of several success strategies of all-ceramic crown with this review article.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.103-108
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• 2024

Kakuro puzzles are NP-complete problems where no way to solve puzzles in polynomial time is known. Until now, a brute-force search method or a linear programming method has been applied to substitute all possible cases. This paper finds a magic rule, a rule for box sizes and unfilled numbers according to sum clues. Based on the magic rule, numbers that cannot enter empty cells were deleted from the box for row and column sum clues. Next, numbers that cannot enter the box were deleted based on the sum clue value. Finally, cells with only a single number were confirmed as clues. As a result of applying the proposed algorithm to seven benchmarking experimental data, it was shown that solutions could be obtained for all problems.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.4
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• pp.65-73
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• 1997

This paper proposes a new method of the structure pruning of dynamic recurrent neural networks (DRNN) using evolutionary computations. In general, evolutionary computations are population-based search methods, therefore it is very useful when several different properties of neural networks need to be optimized. In order to prune the structure of the DRNN in this paper, we used the evolutionary programming that searches the structure and weight of the DRNN and evolution strategies which train the weight of neuron and pruned the net structure. An addition or elimination of the hidden-layer's node of the DRNN is decided by mutation probability. Its strategy is as follows, the node which has mhnimum sum of input weights is eliminated and a node is added by predesignated probability function. In this case, the weight is connected to the other nodes according to the probability in all cases which can in- 11:ract to the other nodes. The proposed pruning scheme is exemplified on the stabilization and position control of the inverted-pendulum system and visual servoing of a robot manipulator and the effc: ctiveness of the proposed method is demonstrated by numerical simulations.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.1
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• pp.80-90
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• 2022

With the development of digital dentistry, it is being applied in various ways of dental treatment. This case report presents the definitive prosthesis designed in advance with a re-established vertical dimension and the digital technology, which determined the amount of tooth preparation, in order to preserve as much tooth structure as possible in a patient with pathological wear of the posterior teeth and loss of vertical dimension. For accurate tooth preparation, the guides of the occlusal and axial surfaces were digitally and additively manufactured. Then, aesthetics and anterior guidance were established at the provisional stage. The information of the provisional restoration was delivered to the definitive stage by double scanning. The digital technology, including the virtual planning and the guided tooth removal, produced the definitive restorations satisfactory to both the patient and clinician.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.377-378
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• 2014

컴퓨터 시스템을 기반으로 이루어지는 범죄 행위로부터 법적인 보호를 받기 위해 관련 법안이 개정되고 이를 수용하기 위한 컴퓨터 포렌식 지원 기술이 다각도로 연구되고 있다. 그러나 시스템 침해자의 시스템 공격 후 본인 흔적을 지우고 나가는 경우 침해자 추출이 어렵다. 또한 휘발성 정보의 손실이 발생하며 디스크에 저장된 비휘발성 정보의 경우 파일의 삭제 및 생성에 의해 디스크 저장영역의 중복된 사용으로 완전한 정보를 추출하는데 문제를 가지고 있다. 이러한 문제를 해결하기 위해 본 연구에서는 시스템 침해자의 공격 형태 및 상황, 환경을 유추하기 위해 행위자를 중심으로 휘발성의 정보를 수집하여 공격 당시의 시나리오의 재현이 가능한 컴퓨터시스템 블랙박스를 설계하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.215-218
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• 2021

심캐시(Shimcache, AppCompatCache) 파일은 Windows 운영체제에서 응용 어플리케이션 간의 운영체제 버전 호환성 이슈를 관리하는 파일이다. 호환성 문제가 발생한 응용 어플리케이션에 대한 정보가 심캐시에 기록되며 프리패치 (Prefetch) 파일이나 레지스트리의 UserAssist 키 등과 같이 응용 어플리케이션의 실행 흔적을 기록한다는 점에서 포렌식적 관점에서 중요한 아티팩트이다. 본 논문에서는 심캐시의 구조를 분석하여 심캐시 파일을 통해 얻을 수 있는 응용 어플리케이션의 정보를 소개하고, 기존 툴 상용도구의 개선을 통해 완전 삭제 등 안티 포렌식 도구의 실행 흔적을 탐지하는 방법을 제시한다.