• 한국초등수학교육학회지
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• 제19권4호
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• pp.563-588
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• 2015

초등학교에서는 여러 가지 이유로 교수학적 변환이 불가피하다. 수학에서는 덧셈과 곱셈은 이항연산, 뺄셈과 나눗셈은 단항연산으로 다루고 있는 반면, 초등에서는 사칙연산 모두를 이항연산으로 취급하는 교수학적 변환을 시도한다. 그런데 사칙연산의 개념을 '익힌다는 것'은 개념이 어떻게 도입되는가가 더 중요하게 부각된다는 점에서 개념을 이해하는 것과는 다르다. 이에 본 연구에서는 자연수와 분수의 사칙연산을 개념 익히기(개념이 어떻게 도입되고 있는지와 연산 선택의 문제)와 연산 사이의 연결이라는 두 가지 관점으로 분석하여, 자연수와 분수의 사칙연산 지도와 관련된 몇 가지 시사점을 도출하였다. 분수의 나눗셈에서는 상황을 바탕으로 연산을 선택하지 않고 곧장 분수의 곱셈과의 연결을 시도했다는 것과 분수의 나눗셈을 그 자체로 이해하기 위해서는 5학년 2학기와 6학년 1학기에 걸쳐 제시되어 있는 분수의 나눗셈을 통합해야 한다는 것 등이 그것들이다. 이는 후속 교과서 개발 시 유용한 참고자료가 될 것으로 판단된다.

• 한국경영과학회지
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• 제22권4호
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• pp.17-35
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• 1997

This paper considers the efficient design of routing path and wavelength assignment in the single-hop WDM optical transport networks. The connection demands between node-pairs are given and a connection between a pair of nodes must be made by only one lightpath. It is assumed that no wavelength conversion is allowed and the physical topology of the network and the number of available wavelengths of a physical link are also given. This paper proposes the method to route a path and assign a wavelength to the path, which guarantees fairness to every node pair. In order to guarantee fairness and maximize connections, an optimization model is established, which successively maximizes minimum connection ratio to the demand of each node pair. A heuristic algorithm with polynomial iterations is developed for the problem since the problem is NP-hard. The heuristic algorithm is implemented and applied to the networks with real problem sizes. The results of the application are compared with GAMS/OSL.

• 한국수학교육학회지시리즈A:수학교육
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• 제45권3호
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• pp.275-293
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• 2006

The purpose of this study was to analyze the connection between students' errors and prior knowledge as an attempt to design an efficient teaching method in decimal computation. A survey on decimal computations was conducted in two 6th grade elementary school classrooms. Error patterns on decimal computations were analyzed and clinical interviews were conducted with 8 students according to their error patterns. Main errors resulted from the insufficient understanding of prior knowledge such as place value, connection between decimals and fractions, meaning of operations, and computation principles of fractions. In order to help students overcome such obstacles, a teaching experiment was designed in a manner that strengthens a profound understanding of prior knowledge related to decimal computations, and connects such knowledge to actual decimal calculations. This study showed that well-designed lesson plans with base-ten blocks might decrease students' errors by helping them understand decimals and connect their prior knowledge to decimal operations.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.822-828
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• 2005

Customer satisfaction becomes one of the important managerial concerns associated with corporate competency in current competitive environment for Internet communication service companies. Hence, it is demanding to improve a company's customer satisfaction through the total quality management perspective. In practice, engineers as well as the management hope to find major quality characteristics with Internet communication network that is closely related to customer satisfaction, consequently aiming to the raise of their company's customer satisfaction. This paper presents an empirical relationship analysis between network quality characteristics and customer satisfaction on Internet communication. Methodologically, the relationship analysis framework is based on the regression variable selection procedures. In this framework, it is implemented that; 1) iterative model building; and 2) consistent criteria application to statistical tests for selecting significant variables. A case study shows that; 1) the customer satisfaction on the network connection seems to be more closely related to the network quality characteristics compared with the customer satisfaction on the network speed; and 2) the download disconnection rate has relatively evident relationship with the customer satisfaction on the network connection.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2008년도 추계학술대회 및 정기총회
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• pp.348-352
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• 2008

KJCCS(Korean Joint Command & Control System) is a system that integrate each military tactics C4ISR into JCS(Joint Chiefs of Staff) level. It is established in major CP(Commanding Post) and provides all battlefield situation in real time by sharing that between connection troops. The objective of this study is to suggest a way for the measurement of force improvement effectiveness of KJCCS. C2 model is applied to measure force improvement effectiveness of KJCCS. This study will be also present a requirement logic for C4ISR system acquisition later.

• Journal of Chest Surgery
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• 제22권1호
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• pp.25-31
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• 1989

Forty-five patients, aged 16 months to 15.5 years mean 69 months, with a wide variety of cardiac malformations underwent the modified Fontan operation between Sep. 1986 to Aug. 1988. Nineteen patients had previously undergone palliative operations mainly modified B-T shunt. Twenty patients had a mean pulmonary artery pressure greater than 15 mmHg, with nine operative deaths. Thirteen patients had anomalies of systemic venous connection and seven patients had anomalies of pulmonary venous connection. There were eighteen patients under the age 4 years and fifteen of them survived [83.3%]. Eighteen patients had a pulmonary vascular resistance [PVR] more than 2.5U/m, and nine died [50%] whereas two of twenty-three with a PVR less than 2.5U/m died[8.6%]. PVR and anomalies of pulmonary venous connection had a significant influence on survival, but age and anomalies of systemic venous connection did not. Amount of pleural effusion drained postoperatively and PVR had positive linear correlation. Pulmonary artery pressure was not an independent predictor of outcome and pulmonary artery pressure alone should not contraindicate a Fontan procedure if PVR is low. In general, the Fontan operation should be done at a younger age less than 4 year to avoid ventricular dysfunction due to long-standing exposure to hypoxia.

• 대한전자공학회논문지TC
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• 제44권7호통권361호
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• pp.70-80
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• 2007

차세대 이동 네트워크에서는 다양한 무선 접속 기술이 공존하게 된다. 이에 따라, 다양한 무선망에서 QoS를 지원하는 분산 방식의 호 수락 제어 구조인 SmartCAC를 제안한다. 본 논문은 네트워크간 정보 수집이 필요없는 분산방식을 위하여 모바일 노드와 네트워크간의 상호동작을 이용한다. SmartCAC는 기본적으로 VHO 호와 새로운 호1의 구분이 가능하도록 함으로써 VHO 호에 핸드오프를 위해 예약된 채널을 사용할 수 있도록 한다. 또한, 효율적인 호 수락 제어를 위하여 QoS 요구와 네트워크 사용에 대한 delay와 reliability를 다룬다. 뿐만 아니라, 이종망에서 네트워크 필터링을 할 수 있도록 모바일노드의 스피드를 이용한다. 이종망의 상태정보를 알 수 없는 모바일노드가 네트워크의 상태정보를 받아 비교할 수 있도록 확장된 프로토콜을 제시하고, 시뮬레이션 연구에서 기존의 CAC 방식과 제어메시지에 의한 비용을 비교하여 37%에서 96%까지 향상되는 효과를 입증한다.

• 융합보안논문지
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• 제14권4호
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• pp.55-60
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• 2014

본 연구에서 제안하는 암호화 모듈 품질평가 체계는 ISO/IEC 9000 품질체계를 참조하여 Quality, Quality Factor, Quality Subfactor, Metric로 계층화된다. 암호화 알고리즘 실무적용 프로세스는 암호화 알고리즘 장단점 진단을 기초로 하여 암호화자산 평가, 알고리즘선택 포인트 분석, 품질 항목(quality factor) 도출, 제약조건도출, 암호모듈 품질평가체계 설계 등 5개단계로 설정한다. 이 5개 단계는 현장중심의 암호화 작업사례를 진단하여 업무에서 가장 필수적으로 수행되어야 할 작업순서를 도출한 것 이다. 2-Factor간 연계지표는 암호화 모듈의 품질항목(quality factor)을 발굴하고 이 품질 항목을 확보하는 환경인 암호화 작업의 제약조건 두가지 영역이다. 본 연구는 암호화 모듈 실무현장 적용체계를 하나의 표준화 모델로 제시한다. 우리는 정보기술 환경의 급속한 변화에 부응하여 암호화 알고리즘 개발과 현장 적용 모델을 다양하게 개발하므로서 암호화의 효율을 기대할 수 있을 것이다.

• 한국문헌정보학회지
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• 제34권3호
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• pp.5-23
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• 2000

본 연구에서는 대전지역에서 제공되는 이동도서관의 운영실태와 이용행태의 조사 분석을 통해서 이동 도서관의 운영개선과 이용활성화 방안을 모색하였다. 대전시의 32개 지역에서 운영되고 있는 이동도서관에 대하여 순회지역 및 정차시간의 적합성, 이용자환경과 대출자료유형의 관련성, 지역내의 도서대여점의 영향 등을 분석하여 자원봉사자의 활용, 모 도서관장서와의 연결, 서비스프로그램의 개발, 홍보활동의 강화 등 운영개선 방안을 제시하였다.

• International Journal of Vascular Biomedical Engineering
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• 제1권2호
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• pp.36-41
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• 2003

Both flow visualizations and computational fluid dynamics were performed to determine hemodynamics in a total cavopulmonary connection (TCPC) model for surgically correcting congenital heart defects. From magnetic resonance images, an anatomically correct glass model was fabricated to visualize steady flow. The total flow rates were 4, 6 and 8L/min and flow rates from SVC and IVC were 40:60. The flow split ratio between LPA and RPA was varied by 70:30, 60:40 and 50:50. A pressure-based finite-volume software was used to solve steady flow dynamics in TCPC models. Results showed that superior vena cava(SVC) and inferior vena cava(IVC) flow merged directly to the intra-atrial conduit, creating two large vortices. Significant swirl motions were observed in the intra-atrial conduit and pulmonary arteries. Flow collision or swirling flow resulted in energy loss in TCPC models. In addition, a large intra-atrial channel or a sharp bend in TCPC geometries could influence on energy losses. Energy conservation was efficient when flow rates in pulmonary branches were balanced. In order to increase energy efficiency in Fontan operations, it is necessary to remove a flow collision in the intra-atrial channel and a sharp bend in the pulmonary bifurcation.