• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권11호
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• pp.5253-5270
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• 2016

With device-to-device (D2D) communications, an inactive user terminal can be utilized as a relay node to support multi-hop communication so that connective experience of the cell-edge user as well as the capacity of the whole system can be significantly improved. In this paper, we investigate the spectrum sharing for a cooperative relay assisted D2D communication underlying a cellular network. We formulate a joint relay selection and channel assignment problem to maximize the throughput of the system while guaranteeing the quality of service (QoS) requirements of cellular users (CUs) and D2D users (DUs). By exploiting coalition formation game theory, we propose two algorithms to solve the problem. The first algorithm is designed based on merge and split rules while the second one is developed based on single user's movement. Both of them are proved to be stable and convergent. Simulation results are presented to show the effectiveness of the proposed algorithms.

• 한국안전학회지
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• 제27권1호
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• pp.32-43
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• 2012

"low and old age trend" is a big social national problem in korea but also in foreign countries. The Government pursues a policy for aged people to take part in construction site as labours. Low childbirth and avoidance of 3D work kinds lead to exposure of aged workers to industry work places. According to korea department of labour, it is expected that 18% of total economic activity people in 2008 to 27.2% in 2018 be increased with age of more than 55 old years. Therefore, It is needed that more countermeasures for old workers should be taken for safer work conditions. This old workers with more than 55 old years contain major portion of accident occurrence in construction industry. It is found that accident rate in construction industry can be decreased if appropriate technical safety training is provided to them who wish to work at construction sites. Statistic analysis such as frequency, cross, logistic regression using program package SPSS 13.0 has been made after collecting questionnaire survey of more than 330 workers at construction sites.

• 한국가정과교육학회지
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• 제31권2호
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• pp.1-18
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• 2019

본 연구의 목적은 교과역량 '실천적문제해결능력'과 '관계형성능력'의 분석준거를 설정하고 2015 개정 중학교 기술·가정교과서의 핵심개념 '관계' 관련 단원을 분석준거에 따라 분석하는 데 있다. 12종 출판사의 중학교 '기술·가정 2' 교과서의 핵심개념 '관계' 관련 단원에서 활동과제를 중심으로 개발된 분석 준거에 따라 분석한 결과는 다음과 같다. 첫째, 교과서에 구현된 교과역량이 출판사별로 차이가 많았다. '실천적문제해결능력'은 A교과서, E교과서와 G교과서가 높게 나타났고 반면 D교과서의 빈도가 가장 낮았다. '관계형성능력'은 K교과서, A교과서가 높게 나타났고 가장 낮은 빈도를 보인 것은 J교과서였다. 둘째, '실천적문제해결능력'과 '관계형성능력'의 역량별 하위요소 중심으로 12종 교과서 전체의 활동과제들을 살펴보면, 우선 '실천적문제해결능력'의 가치판단이 가장 높은 빈도를 보였고 이어서 논리적 사고, 실천적 추론, 의사결정 등으로 나타났다. '관계형성능력'에서는 가족관계와 공동체의식이 가장 높은 빈도로 나타났고 의사소통, 갈등관리, 타인존중 등의 순으로 나타났지만, 환경 및 생태의식은 구현되지 않았다. 이와 같이 2015 개정 중학교 기술·가정 12종 교과서의 핵심개념 '관계' 관련 단원은 교육과정의 세부목표에서 제시된 두 교과역량을 대체로 구현하고 있다.

• 공학교육연구
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• 제19권5호
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• pp.13-24
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• 2016

The purpose of this research is to examine the characteristics of team interaction according to the creativity of team members. Research subjects to achieve this purpose included 28 students who are in engineering education in the College of Education at A University in Daejeon and have taken robot-related courses. Through first and second MBTI, and TTCT tests, the final homogeneous and heterogeneous teams were formed, and an experimental study was conducted by developing team design activity assignment. The major research results were as follows. In terms of a comprehensive view on interaction frequency, both homogeneous team and heterogeneous team suggested had the highest frequency in suggesting opinions. However, each of the team members in the homogeneous team had different communication frequency among each other while each team member in the heterogeneous team had almost similar frequency. A microscopic analysis of the communication process of homogeneous team showed that the team members' roles were divided among each other in communication. Next, according to the microscopic analysis of the heterogeneous team's communication process, the team members exchanged opinions in the beginning, talked to themselves in words that were hard to understand the meanings, and they stopped having conversations in the end. Due to such decrease in communication, two team members could not solve the confusing state of being unable to understand each other's opinions and failed to complete their assignments. The microscopic analysis demonstrated that the homogeneous team had a smooth interaction, because when one team member suggested an opinion during a conversation, other team members agreed with it through a discussion. However, the members in the heterogeneous team experienced confusion as they could not understand each other's conversation and could not overcome this problem, leading to lack of conversations.

• 한국전자통신학회논문지
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• 제13권4호
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• pp.729-736
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• 2018

주파수 오프셋으로 인하여 직교 주파수분할다중화의 수신 심볼에는 채널간간섭이 발생된다. 채널간간섭 자기소거법은 직교 주파수분할다중화 심볼의 부채널에 할당되는 신호를 조정함으로써 다른 부채널에 의한 간섭을 상쇄시키는 기술이다. 기존 인접심볼반복법은 원거리 부채널에 의한 간섭을 감소시키기는 하지만 가장 인접한 부채널에 의한 간섭은 완화시키지 못하거나 심지어는 증가시키는 경우도 있다. 이러한 문제점을 해결하기 위하여 본 논문에서는 새로운 인접심볼반복 기반 채널간간섭 자기소거법을 제안하고 성능을 분석한다. 여기서는 연속된 3개 부채널의 간섭계수를 이용하여 구한 t-파라미터를 적용한다. 그 결과, 제안된 방법은 원거리 부채널에 의한 영향을 감소시키는 능력은 기존 방법과 거의 동일한 반면 최인접 부채널에 의한 채널간간섭은 크게 감소시킬 수 있는 것으로 나타났다.

• 한국학교보건학회지
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• 제12권2호
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• pp.217-230
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• 1999

The purpose of this study is to find out problems in obesity management through survey and analysis of the actual conditions from the view of a elementary schools school-nurses and to establish fundamental data for efficient obesity management. The subjects for this study were 313 numbers of elementary school-nurses in Kyung-Sang-Pook-Do. The data were collected through mail questionaries from November 1 to November 30, 1997. The major findings in this survey were as follows: 49.8% of the school-nurses who responded in the survey were in their 30s. The average career was 7.3years. The average service duration in their present school was 2.3 years, 55.6% of them were serving at schools which have less than ten classes total 77.2% of them were serving rural areas, 79.6% of them were serving at schools with fewer than 100 obese students. The total obesity prevalence rate was 11.4%, 13.3% were girls, 9.3% were boys. The measurement of height and weight is performed once a year for all surveyed students (91.7%), but obese students were measured as much five times (51.1%). The rate of obesity management planning was 74.1%, however the rates of evaluation and role assignment were 41. 2%, and 24.3%. 79.6% of the surveyed schools have health education classes for obesity, the rate compared (8.0 periods per year) to the whole of health education (79.1 periods per year) is 10.1%. 99.9% of the schools had counseling rooms for obesity (combined with nursing rooms) but they were used. The roote of individual counseling was 84.3%. The frequency counseling was six times a year for about 15 minutes. Obesity counseling records were kept 93.6% of the time and individual information cards were kept 98.7% of the time. The frequency of parents counseling was 42.8% and the survey shows that the main problem here was insufficient counseling facilities. The frequency of dietary guidance and exercise therapy was 84.3% and the dietary instructor was usually the school nurse at 51.7%. The frequency of obesity student exercise was 1-2 times a week and more-than-10-minutes at a time. They skip rope during the morning self-study class. The number on problem of exercise guidance at 56.2% was students' non-cooperativeness. School-nurses, 87.9%, answered that obesity management at school is necessary and 86.9% mentioned the shortage of obesity related information in present physical exercise books. From the plural responses of executing the obesity management, there are many similar problems: lack of knowledge and non-cooperation in parents at 41.9%, is predominant followed by of knowledge and non-cooperation in the children. The third problem is the lack of funds and facilities.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.148-154
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• 2020

본 논문에서는 대학 기숙사에서 이용 빈도가 높은 특정 공용 공간의 접근성을 높이기 위한 공실 배정에 대해 고려한다. 접근성 향상을 위하여, 학년에 따른 이용 빈도의 차이를 반영하여 학생들의 개인 공실에서 특정 공용 공간까지의 총 이동거리를 최소화하는 정수계획법 모델을 제시한다. 또한 각 공실의 최대 허용 인원을 제한하고 하나의 공실에는 같은 학년으로만 배정되도록 제약하였으며, 제시된 모델은 공급사슬관리에서 다루는 입지 선정 문제와 유사함을 보여준다. 사례 연구를 위하여 제시된 정수계획법 모델을 A대학교 기숙사에 적용하여, 소규모 그룹에 대한 공실 배정 결과를 도출하였으며, 특정 공용 격실을 이용하는 횟수가 많은 저학년 학생일수록 접근성을 고려하여 가까운 곳에 배정되었음을 확인하였다. 추가적으로 고학년부터 공실 배정에 대한 우선순위를 부여할 경우, 저학년이 우선적으로 배정될 때 벌과비용을 목적함수에 추가함으로써 이를 방지하도록 하는 모델을 제시하였다. 이러한 결과를 바탕으로 여러 공용 공간에 대한 학생들의 복합적인 요구들에 부합하도록 공실을 배정하는 방안을 제시할 수 있다.

• 한국통신학회논문지
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• 제33권7A호
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• pp.776-785
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• 2008

본 논문에서는 소형 와이브로 기지국을 실내에서 운용하고자 할 때 중앙 관리 서버를 통해 기지국의 무선 파라미터를 최적화하는 방법에 대해 논의한다. 운용요원에 의해 수동으로 기지국의 무선 파라미터가 설정되던 기존의 방식과는 달리, 원격 컨트롤러를 통해 자동으로 무선 파라미터들이 설정된다는 점에서 소형 와이브로 기지국은 자가 설정 기지국 (Self-Configurable Radio Access Station: SC-RAS)으로도 명명된다. 이러한 실내 SC-RAS 망을 도입하는 주된 목적이 전송 전력의 세기를 높여 건물 안에서 발생하는 음영지역 문제를 해결하기 위함이지만, 동시에 한 가지 고려해야 하는 점은 SC-RAS가 기존 와이브로 망에 미치는 신호 간섭을 최소화해야 한다는 것이다. 결과적으로 SC-RAS의 전송 전력과 주파수 (Frequency Assignment :FA)를 올바르게 선택하는 것이 매우 중요하다. 본 논문에서는 이 SC-RAS의 무선 파라미터 최적화 문제를 혼합 정수 계획법 (Mixed Integer Programming: MIP)을 이용하여 풀고, SC-RAS 설치 전과 후의 성능을 비교 및 분석한다.

• Journal of Communications and Networks
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• 제18권6호
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• pp.913-925
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• 2016

In-band wireless full-duplex is a promising technology that enables a wireless node to transmit and receive at the same time on the same frequency band. Due to the complexity of self-interference cancellation techniques, only base stations (BSs) are expected to be full-duplex capable while user terminals remain as legacy half-duplex nodes in the near future. In this case, two different nodes share a single subchannel, one for uplink and the other for downlink, which causes inter-node interference between them. In this paper, we investigate the joint problem of subchannel assignment and power allocation in a single-cell full-duplex orthogonal frequency division multiple access (OFDMA) network considering the inter-node interference. Specifically, we consider two different scenarios: i) The BS knows full channel state information (CSI), and ii) the BS obtains limited CSI through channel feedbacks from nodes. In the full CSI scenario, we design sequential resource allocation algorithms which assign subchannels first to uplink nodes and then to downlink nodes or vice versa. In the limited CSI scenario, we identify the overhead for channel measurement and feedback in full-duplex networks. Then we propose a novel resource allocation scheme where downlink nodes estimate inter-node interference with low complexity. Through simulation, we evaluate our approaches for full and limited CSIs under various scenarios and identify full-duplex gains in various practical scenarios.

• 한국통신학회논문지
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• 제39A권10호
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• pp.593-600
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• 2014

OFDMA (orthogonal frequency division multiple access) 시스템은 주파수 선택적 페이딩 문제를 효율적으로 해결하며 최적의 부반송파 및 송신 전력을 할당함으로써 보다 향상된 성능을 얻는다. Two-way 릴레이는 양방향 통신을 통해 기존의 반이중 릴레이보다 향상된 주파수 효율을 제공한다. WiBro와 같은 레거시 OFDMA 시스템에 two-way DF (decode-and-forward) 릴레이를 적용 시 파일롯 재배치 문제와 자가 간섭으로 인한 채널 추정 및 수신 신호 복호가 어려운 문제가 발생한다. 본 논문에서는 WiBro와 같은 레거시 OFDMA 시스템에 적합한 two-way DF 릴레이 자원 할당 기법을 제안한다. 제안된 기법은 릴레이와 연결된 노드를 기지국과 직접 통신하는 노드로 간주하여 부반송파를 할당한다. 그리고 다른 노드가 사용하지 않는 부반송파를 중첩 할당함으로써 직교 할당으로 발생하는 대역폭 손실을 보완한다. 전산모의실험을 통해 제안된 자원 할당 기법의 성능 향상을 검증한다.