• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.93-100
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• 1998

The basic systems of spatial structures such as shells, membrane, cable-nets and tensegrity structure have been developed to create the large spaces without column. These structures may have large freedom in scale and form, and especially tensegrity structures are received much attention from the view points of their light weight and aesthetics. But There re some difficulties concerning structural stability, surface formation and construction method. One of the way to solve these problems reasonably is a combination of tensile members and rigid members. A structural system based on this concept is referred to as the "HTS ( Hybrid Tension Structure )". This is a type of flexible structural system which is unstable initially, because the cable material has little initial rigidity. As cable - dome hybrid structures is a type of HTS, the initial stress for the self- equilibrated system having stable state have to be introduced. To determine initial stress having stable state, the shape finding analysis is required before the stress - deformation analysis. In this paper, the primary objective is to derive the nonlinear finite element formula of cable and truss members considering geometric nonlinearity for shape finding of cable-dome, and to propose the method to decide the initial stress by the shape analysis of cable-dome hybrid structure with the self-equilibrated state.

• 대한수학교육학회지:수학교육학연구
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• 제16권4호
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• pp.367-386
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• 2006

본 논문에서는 구성주의 교육관의 관점에서 컴퓨터와 수학교육의 관계를 바라보는 '컴퓨터와 수학교육'에 대해 다룬다. '컴퓨터와 수학교육'은 그 필요성에 비해 최근까지 원활히 이루어지지 못했다. 그 이유는 먼저 그 구성요소들 사이의 관계가 명확하게 이해되지 못하였고, 이에 따라 구성주의에 대한 명확한 실천적 전략이 부족하였고, 서로 다른 컴퓨터 하드웨어-소프트웨어 환경들이 유기적으로 연결되지 못했기 때문이다. 이에 바람직한 '컴퓨터와 수학교육'을 위해서는 먼저 구성요소들 사이의 관계를 이해하고, 이를 바탕으로 '컴퓨터와 수학교육'의 실천적 설계 전략을 모색하며, 개별적인 소프트웨어 환경을 마이크로월드의 관점에서 통합적으로 연계시켜야 할 필요가 있다. 본 논문에서는 이러한 문제의식을 가지고 '컴퓨터와 수학교육'의 구성요소인 학생, 수학, 컴퓨터를 중심으로 관계된 이론을 고찰하여 각각에 대한 구체적 실천적 전략으로 구성주의. 함수화, 인터넷 상호작용의 원리를 도출한다. 또한 역사적으로 가장 성공적이고 대표적인 '컴퓨터와 수학교육' 환경인 Logo와 동적 기하 환경(DGS)을 이러한 관점으로 분석 고찰하여, Logo를 행동 문자 명령과 대수적 문자조작을 통해 재귀적 패턴의 탐구가 가능한 환경으로 발전시키고, 점들 사이의 기하적 관계를 다루던 DGS를 관계식과 대수기하적 탐구가 가능한 환경으로 설계, 구현한다. 나아가 Logo와 DGS의 이러한 수준 상승이 가지는 수학교육적 의미를 고찰하고, 타일 및 전개도 등의 새로운 대상을 도입하여 통합 마이크로월드를 구현한다. 본 논문에서는 Logo와 DGS, 그리고 통합 환경을 하나의 JavaMAL 인터넷 환경 속에서 통합 설계하고 이를 구현하며 나아가 그 의미를 논의한다.

• 대한수학회논문집
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• 제26권1호
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• pp.135-149
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• 2011

Using (r, s)-preopen sets [14] and pre-${\omega}_t$-closures [6], a new kind of covering property $P^t_{({\omega}_r,s)}$-closedness is introduced in a bitopological space and several characterizations via filter bases, nets and grills [30] along with various properties of such concept are investigated. Two new types of cluster sets, namely pre-(${\omega}_r$, s)t-${\theta}_f$-cluster sets and (r, s)t-${\theta}_f$-precluster sets of functions and multifunctions between two bitopological spaces are introduced. Several properties of pre-(${\omega}_r$, s)t-${\theta}_f$-cluster sets are investigated and using the degeneracy of such cluster sets, some new characterizations of some separation axioms in topological spaces or in bitopological spaces are obtained. A sufficient condition for $P^t_{({\omega}_r,s)}$-closedness has also been established in terms of pre-(${\omega}_r$, s)t-${\theta}_f$-cluster sets.

• 한국지능시스템학회논문지
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• 제16권3호
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• pp.291-296
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• 2006

상황은 단일 사건에 의해 결정되는 경우도 있지만, 많은 경우 일련의 사건이 특정 시간 제약을 만족하면서 발생할 때 상황이 결정된다. 따라서 상황에 대한 추론은 시간 제약 조건 만족 여부와 함께 사건의 발생을 순서를 확인하는 방법으로 수행될 수 있다. 한편, 어떤 상황은 분명하게 정의되는 것이 아니라 애매한 개념을 사용하여 기술되기 때문에, 퍼지 개념을 이용한 상황 기술과 이에 대한 추론이 필요하다. 한편, 유비쿼터스 환경에서와 같이 여러 대상에 대한 상황을 유추하여 서비스를 제공해야 하는 경우에, 대상 간에 동일한 상황이 발생할 수 있기 때문에 이에 대한 고려가 필요하다. 이러한 상황 추론을 위해서 이 논문에서는 Fuzzy Colored Timed Petri net 모델이라는 상황 추론 모델에 대해서 제안한다. 제안한 모델은 Timed Petri net 성질을 이용하여 일련의 사건 발생을 모델링하고, Colored Petri net의 성질을 이용하여 다수 대상에 대한 상황 추론을 허용하며, fuzzy 토큰 개념을 이용하여 애매한 개념을 사용하여 정의된 상환에 대한 추론을 가능하게 한다.

• 대한지역사회영양학회지
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• 제26권6호
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• pp.429-440
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• 2021

Objectives: Standardized guidelines and reference points for a food security policy are necessary to guarantee that basic social safety nets work properly. Therefore, this study aimed to explore the basic concepts and detailed dimensions of food security, including the potential relevant indicators, and sought to establish standardized well-being baselines. Methods: A literature review and 14 expert roundtable discussions were carried out to analyze and extract the key concepts of food security. After determining these concepts and detailed dimensions of food security, a conceptual framework was modeled. Then, indicators for each local government that could be monitored and evaluated for each sub-area were suggested. Results: The concept of food security was defined as follows: Individuals should be provided with sufficient, safe, and quality food, which should be accessible to the community and available for use to achieve health and well-being. In addition, food security should be ensured sustainably in a changing environment. Four dimensions were suggested while conceptualizing food security. First, sufficient food, which means sufficient food supply in quantity, quality, and safety. Second, equitable food which includes creating environments in which high-quality and safe food can be purchased at an appropriate price and can be provided regardless of the socioeconomic gap. Third, healthy food which should be provided to promote people's health and happiness through the eco-friendly consumption of food. Fourth, sustainable food, which can be supplied in a sustainable manner and as part of an eco-friendly food system that considers the conservation of natural environments. Conclusions: The basic concepts and detailed areas of food security including the potential indicators proposed in this study, may be useful for developing and implementing various policies and programs to support food and nutrition security in the future.

• 한국항해학회지
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• 제21권2호
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• pp.47-58
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• 1997

The purpose of this study is to find out the impacts of VTS on the marine safety and users' opinion on the VTS which have been being operated in the port of Pohang for the last 3 years and is to suggest a guideline to the successful operation of VTS in the future. This study is based upon the questionnaire survey and the respondents include 236 masters/mates of merchant vessels who have visited the port of Pohang and 6 pilots who have been working in the port. From the questionnaire results, this study notes the following conclusions related to the VTS operations. (1) A few of the respondents (mainly foreigners) do not understand the entering procedure of the port and the fundamental concept of VTS. Accordingly, the more active VTS services have to be provided for the mariners. (2) It was found that themost dangerous factors in tehvicinity of the port were the floating materials, fishing nets, andillegal fishing activities inthe fairway. Therefore, the proper surveillance, stricter enforcement of Acts and the instructive education for the fishermen are required to avoid the risks. (3) A majority of the respondents agreed the VTS has contributed to the safety of vessel traffic, and they pointed out ' the assiatances in reduced visibililty conditions' is the most important task of VTS. The amount of 75.6% of the respondents answered that they have experienced the assistance from VTS more than 1 time since the system was established in the port of Pohang . Also 44.2% of the respondents considered they were able to avoid marine casualties such as collision, ramming or agrounding with the VTS assistances. (4) 49.2% of the respondents preferred the passive information services , while, 38.8% of them preferred the positive control advices in the case of encountering any potential risks. VTS iperators have to consider seriously when they provide the positive control advices of ship's course and speed. (5) A majority of the respondents confirmed that the prot and its approaches is suitable for the VTS coverge . To extend the service areas of the VTS and to improve radar detecting ability, the use of radar transponders are seen as the ideal method. (6) A minority of the respondents pointed out 'the improper orders or recommendatinos caused by the poor decision making' firstly, ' the language problem(sea-speaking in English)' secondly, as the deficiency of personal qualification. It seems, therefore, theat the personal efforts of the operators and systematic training programmes for them are necessary to solve the problems.