• 대한전자공학회논문지SP
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• 제46권4호
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• pp.42-49
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• 2009

본 논문에서는 red, green, blue(RGB) 광학 센서를 이용하여 RGB light-emitting diode(LED) back light unit(BLU)의 출력색 자극의 변화를 점검하여 RGB LED BLU가 시간에 따라 일정한 목표 색 자극을 출력할 수 있도록 하는 RGB LED BLU 구동 전류 펄스 duty 값을 도출하는 알고리즘을 제안한다. 우선, 현재 RGB LED BLU가 발하는 색 자극 정보를 획득하기 위해 RGB 광학 센서의 출력으로부터 CIEXYZ 색 자극을 계산할 수 있는 RGB to XYZ 변환 행렬을 도출한다. 다양한 RGB LED BLU 색 자극 샘플에 대한 RGB 광학 센서의 출력 값과 CIEXYZ 색 자극 값의 쌍을 이용하여 다항 회귀 방정식을 만들고 각 항의 계수로 행렬을 구성한다. 다음으로, 현재 RGB LED BLU 상태에서 목표 색 자극 값을 발할 수 있는 duty 값을 구하기 위해 목표 색 자극으로부터 duty 값을 계산할 수 있는 XYZ to Duty 변환 행렬을 도출한다. 현재, 한 단계 이전, 두 단계 이전 시점에서 RGB 광학 센서의 출력으로부터 추정한 CIEXYZ 값과 그때 인가된 duty 값의 쌍을 이용하여 다항 회귀 방정식을 만들고 각 항의 계수로 행렬을 구성한다. 일정 시간 간격으로 RGB LED BLU의 출력 색 자극을 점검할 때마다 XYZ to Duty 변환 행렬은 RGB LED BLU의 현재 상태에 적응적으로 변하게 되어 목표 색 자극을 출력할 수 있는 duty 값을 계산할 수 있게 된다.

• 한국학교ㆍ지역보건교육학회지
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• 제19권2호
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• pp.1-10
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• 2018

Objectives: The purpose of this study is to expand of workplace by analyzing the duty and workplace of health education specialist and by presenting professional duty for health education specialist. Methods: 22 papers related to health education experts were finally selected from 1993 to 2017(25 years). The selected literature analyzed the title, researchers, the publishing agency, the publication year, the main contents, and duty and workplace of the health education specialist. Results: The studies on health education specialists comprised 5 cases (22.7%) between 1993 and 1999, 3 cases (13.6%) between 2000 and 2009, 14 cases (63.6%) between 2010 and 2017. Health education specialists core duty were diagnosing health education needs, planning health education programs, developing health education methods and materials, performing and managing health education programs, evaluating and conducting research on health education programs, and health communication. The workplace were 11 for medical institutions (55.0%), 9 for healthcare organizations (45.0%) and 8 for schools (40.0%). Conclusions: In addition to the basic core duty, professional and differentiated duty capabilities such as managing the target, generating health information, encouraging involvement of the target, and mobile health care should be developed.

• 한국세라믹학회지
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• 제50권2호
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• pp.108-115
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• 2013

Oxide coatings were prepared on Al-1050 substrates by an environment-friendly plasma electrolytic oxidation (PEO) process using an electrolytic solution of $Na_2SiO_3$ (8 g/L) and NaOH (3 g/L). The effects of three different duty cycles (20%, 40%, and 60%) and frequencies (50 Hz, 200 Hz, and 800 Hz) on the structure and micro-hardness of the oxide coatings were investigated. XRD analysis revealed that the oxides were mainly composed of ${\alpha}-Al_2O_3$, ${\gamma}-Al_2O_3$, and mullite. The proportion of each crystalline phase depended on various electrical parameters, such as duty cycle and frequency. SEM images indicated that the oxide coatings formed at a 60% duty cycle exhibited relatively coarser surfaces with larger pore sizes and sintering particles. However, the oxides prepared at a 20% duty cycle showed relatively smooth surfaces. The PEO treatment also resulted in a strong adhesion between the oxide coating and the substrate. The oxide coatings were found to improve the micro-hardness with the increase of duty cycle. The structural and physical properties of the oxide coatings were affected by the duty cycles.

• Journal of Power Electronics
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• 제17권2호
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• pp.368-379
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• 2017

In this paper, a direct torque control algorithm with novel duty cycle-based modulation is proposed for permanent magnet synchronous motor drives fed by neutral-point clamped three-level inverters. Compared with the standard DTC, the proposed algorithm can suppress steady-state torque ripples as well as ensure neutral-point potential balance and smooth vector switching. A unified torque/flux evaluation table with multiple voltage vectors and precise control levels is established and used in this method. This table can be used to evaluate the effects of duty-cycle vectors on torque and flux directly, and the elements of the table are independent of the motor parameters. Consequently, a high number of appropriate voltage vectors and their corresponding duty cycles can be selected as candidate vectors to reduce torque ripples by looking up the table. Furthermore, small vectors are incorporated into the table to ensure the neutral-point potential balance with the numerous candidate vectors. The feasibility and effectiveness of the proposed algorithm are verified by both simulations and experiments.

• 전자공학회논문지
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• 제49권12호
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• pp.45-55
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• 2012

센서 네트워크는 센서가 설치된 지역에서 감지된 데이터를 무선으로 전달하는 기술로서, 기존 방식과 달리 에너지 효율이 매우 중요한 성능요소이다. 이러한 특성에 따라 많은 WSN MAC 프로토콜에서는 Wakeup과 Sleep을 반복하여 수행하는 Duty Cycle 기법을 활용하고 있지만, 고정적인 Wakeup 구간의 설정에 따라 획일화된 에너지 성능과 수신 성공률로 인하여 성능이 제한적이다. 본 논문에서는 이러한 Duty Cycle 기반의 MAC 프로토콜을 개선하기 위하여, 채널 환경에 따라 동적으로 Wakeup 구간을 가변화시키는 기법을 제안한다. 제안하는 방식은 트래픽이 높은 환경에서 Wakeup 구간을 증가시켜 수신 성공률을 높이고, 트래픽이 낮은 환경에서 Wakeup 구간을 줄여 에너지 성능을 향상시켰다. 또한 본 논문에서는 제안하는 방식의 성능에 대한 효율적인 평가를 위하여 기존 동기식 및 비동기식 MAC의 결과와 제안방식을 적용한 MAC의 결과를 비교하고 이를 분석하였다.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2001년도 추계공동학술대회 논문자료집 정보화 젼략 패러다임의 변화에 대한 보기술의 대응
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• pp.111-112
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• 2001

• 한국통신학회논문지
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• 제9권3호
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• pp.132-139
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• 1984

병렬 인덕터와 직렬공진회로를 부하로 갖는 E급 동조전력 증폭기의 duty cycle변화에 따른 콜렉터 전압과 전류, 기본 주파수 성분, 부하회로소자 및 출력전력능력에 관한 방정식을 유도하여 최적동작상태의 특성을 해석하며 실제 콜렉터 포화전압을 고려하여 duty cycle이 50%일 때 증폭효율이 90%이상된다는 것을 이론과 실험을 통하여 고찰하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 추계학술발표대회
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• pp.525-526
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• 2009

Due to the limitation of battery life time, energy is one of the most crucial issues for wireless sensor networks. Thus this paper proposes an energy efficient duty cycle scheme to conserve energy mostly. To handle the large varieties of data (i.e., both low and high traffic load) the proposed duty cycle scheme ensures a fair access period (FAP) and a prioritized access period (PAP). The idea presented in this paper able to reduce the collision probability and energy consumption. Finally simulation outputs have demonstrated the effectiveness of the proposed duty cycle task and showed a noticeable performance in terms of energy usage.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 추계학술발표대회
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• pp.527-528
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• 2009

Presuming energy as a crucial resource, several duty cycle based MAC protocol have been proposed for wireless sensor network. However, these protocols have long latency problem for paying more attention on energy efficiency. In this paper, we propose Data Predicted Wakeup Based Duty Cycle MAC (DPW-MAC) for Wireless Sensor Networks for delay sensitive periodic applications in which timely delivery of data is a major concern with the maintenance of duty cycle.

• 유통과학연구
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• 제14권10호
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• pp.47-57
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• 2016

Purpose - This study's purpose is to investigate the market structure of the Korean duty free shop industry that has received recent attention from researchers and practitioners. By raising the question of whether or not the Korean duty free shop industry is unequivocally monopolistic, a wider viewpoint is provided. The study seeks to offer insights and managerial implications for marketers and policy makers who are in charge of regulating major Korean duty free shops. Research design, data, and methodology - The authors use secondary data from various sources, including Korea Customs Service and the Moodie Report, to investigate the structure of the duty free shop industry of Korea. Based on several theories, they present various criteria and statistical evidence such as K-firm concentration ratio, HHI, consumer substitutability, excess profit, and marketing costs. Results - In terms of consumer substitutability, it is difficult to confirm whether or not the Korean duty free shop industry is monopolistic. Notwithstanding monopoly characteristics in terms of market share, neither the company Lotte nor Shilla appear to have market dominating power. It is not easy for either of them to control prices or to achieve a much lower operational profit ratio due to a dominant bargaining power. Moreover, the license is not an economic rent. In this situation, it is not easy for these companies to obtain an excessive profit. Conclusions - Considering that most global duty free shops are trying to go upscale to improve bargaining power, it does not seem likely that rigid regulations are needed in the industry. Even though the Korean duty free industry ostensibly has a monopolistic structure, government and policy-makers should look beyond the surface. They should take global and other reasonable criteria into consideration when they establish or change regulation policies. Thorough understanding and appropriate support are needed for the Korean duty free shop industry. Additionally, duty free shops should position themselves as global companies struggling against unlimited international competition, rather than Korean domestic companies. At the same time, they need to give customers appropriate information about the benefits they provide.