• Journal of Communications and Networks
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• v.7 no.3
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• pp.258-262
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• 2005

An adaptive beamforming system based on code filtering and differential correlation approaches is proposed. The differential correlation method was originally proposed for time delay estimation of direct sequence code division multiple access (DS-CDMA) systems under near-far ratio conditions and the code filtering correlation algorithm, on the other hand, was proposed for array response estimation in DS-CDMA systems under perfect power control. In this paper, by combining differential correlation concept with the code filtering beamforming technology, an accurate estimate of the beam forming weights and an enhanced performance of DS-CDMA systems under sever near-far ratio conditions is achieved. The system performance in terms of beam pattern and bit-error-rate (HER) shows that the proposed adaptive beamformer outperforms the conventional code filtering correlation technique.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.5
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• pp.623-629
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• 2012

In this paper, we analysis the performance of position estimation when adopting Dynamic TDMA(DTDMA) in JTIDS RelNav. JTIDS RelNav is widely understood as a new navigation solution possibly capable to support or take cover of the role of conventional systems including INS or GPS no matter if they are working well or not. By maximizing the efficiency of radio resource management in MAC(Medium Access Control) layer we enhance the system performance without any replacement of hardware.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6A
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• pp.1078-1088
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• 2001

ATM-PON (Asynchronous Transfer Mode Passive Optical Network)에는 두 가지 핵심 기술이 있는데 ranging 프로토콜과 MAC (Medium Access Control) 프로토콜이 그것이다. Ranging 프로토콜은 시간 분할 다중화(Time Division Multiple Access, TDMA) 방식을 사용하는 ATM-PON에서 상향으로 액세스할 때 타임 슬롯의 동기를 유지하게 하기 위해 ONU (Optical Network Unit)를 가상적으로 동일한 거리에 놓는 기술이다. 본 논문에서는 FSAN (Full Service Access Network)과 ITU-T를 중심으로 표준화된 G.983.1의 ranging 프로토콜에 관하여 연구하고 성능분석과 모의실험을 수행한다. 이를 통하여 ranging을 하는데 걸리는 소요시간이 표준안의 권고사항을 만족시키기 위한 필요조건을 도출할 수 있다. 특히 ranging을 할 때 윈도우의 길이를 줄일 수 있는 새로운 방식을 적용하여, 이미 서비스 중에 있는 ONU의 서비스 품질이 저하되는 것을 막을 수 있음을 보여준다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.608-610
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• 2003

Ethernet PON(Passive Optical Network)에서 핵심 기술 중의 하나인 MAC(Media Access Control) 프로토콜은 ONU(Optical Network틴nit)들이 상향으로 트래픽을 전송할 때 공유되어 있는 링크상의 충돌을 방지하고, 효율적인 대역폭을 할당하기 위한 스케줄링 알고리즘을 포함하고 있다. 본 논문에서는 차세대 가입자 망인 Ethernet PON에서 상향으로의 대역폭 부족을 개선하기 위하여, n개의 파장을 사용한 가변 슬롯 할당 TDMA(Time Division Multiple Access) 방식의 MAC 프로토콜을 제안한다. 이를 검증하기 위하여 OPNET 시뮬레이션 도구를 이용해 Ethernet PON 모델을 설계하고 시뮬레이션 한다.

• The Plant Pathology Journal
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• v.33 no.2
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• pp.103-108
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• 2017

World wheat production is now under threat due to the wheat blast outbreak in Bangladesh in early March 2016. This is a new disease in this area, indicating the higher possibility of this pathogen spreading throughout the Asia, the world's largest wheat producing area. Occurrence of this disease caused ~3.5% reduction of the total wheat fields in Bangladesh. Its economic effect on the Bangladesh wheat market was little because wheat contributes to 3% of total cereal consumption, among which ~70% have been imported from other countries. However, as a long-term perspective, much greater losses will occur once this disease spreads to other major wheat producing areas of Bangladesh, India, and Pakistan due to the existing favorable condition for the blast pathogen. The wheat blast pathogen belongs to the Magnaporthe oryzae species complex causing blast disease on multiple hosts in the Poaceae family. Phylogenetic analysis revealed that the Bangladesh outbreak strains and the Brazil outbreak strains were the same phylogenetic lineage, suggesting that they might be migrated from Brazil to Bangladesh during the seed import. To protect wheat production of Bangladesh and its neighbors, several measures including rigorous testing of seed health, use of chemicals, crop rotation, reinforcement of quarantine procedures, and increased field monitoring should be implemented. Development of blast resistant wheat varieties should be a long-term solution and combination of different methods with partial resistant lines may suppress this disease for some time.

• The Korean Journal of Food And Nutrition
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• v.28 no.1
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• pp.134-142
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• 2015

The purpose of this study was to identify the effects of nutrition education on elementary school students based on the theory of multiplex intelligence. Of the 56 elementary school students that participated in this survey, 37 (66.0%) had no siblings. The number of students whose mothers had jobs and those whose mothers did not work were 37 (67.9%) and 18 (32.1%), respectively. Food consumption with ordinary diets was normal in 23 students (41.1%) and the average frequency of snack intake and eating-out was determined to be twice a day (41 students, 73.2%) and once or twice per week (36 students, 64.3%), respectively. The most popular type of food consumed when eating-out was 'fast foods' in 28 students (50.0%). It was determined that on average, 39 students (69.6%) snacked between lunch and dinner time and 31 (55.4%) selected snacks based on information obtained through 'mass media'. Analysis of the effects of nutrition education revealed an increase in the number of correct answers to the question 'foods with high nutritional value are high calorie foods,' with significant difference, but not in other questionnaires. In addition, the correct information for calcium (p<.05), good dietary habits (p<.001), food poisoning (p<.05), and six groups of nutrients in foods (p<.001) improved after nutrition education, with significant differences. As a result, the ratio of correct answers increased after nutrition education, with a significant difference (p<.001). After the education, the experimental group had a higher total score than the control group, with significant difference (p<.01).

• Journal of Korean Public Health Nursing
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• v.26 no.3
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• pp.465-477
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• 2012

Purpose: The purpose of this study was to investigate the influence of breakfast characteristics of university students on their self-regulated learning, attentional control, and fatigue in order to provide-basic data for establishing desirable eating habits, self-regulated learning skills using attentional control, and advisable learning habits of university students. Method: The level of fatigue was estimated using the Visual analogue scale (VAS) and Critical flicker frequency (CFF). Attentional control was measured using the Attentional Control Questionnaire (ACQ) adapted by Yoon. Self-regulated learning was surveyed by the Self-Regulated Learning Test developed by Chung. Data from atotal of 142 university students were collected from November 30 to December 9, 2011. Result: 69% of the subjects skipped their breakfast. Attentional control has a negative correlation with fatigue (r=-.179, p=.033) and a positive correlation with self-regulated learning (r=.352, p<.001). The multiple regression model of self-regulated learning consists of attentional control (t=3.218, p=.002), commuting time (t=-3.076, p=.003), understanding the importance of breakfast (t=-2.413, p=.008), and skipping breakfast(t=-2.195, p=.030) and its R-square was 21.8%. Conclusion: Learning efficiency of university students should be improved by means of attentional control, which is related to self-regulated learning. Also, it is essential for university students to establish healthy lifestyles including regular eating habits and attentional control, in order to improve their self-regulated learning.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.669-676
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• 2008

The adaptive resource optimization problem in multi-input multi-output orthogonal frequency division multiple access (MIMO-OFDMA) systems is addressed. This paper, adaptive modulation and coding(AMC) and power control algorithms is proposed with SFC(Space-Frequency Coding), which aims to maximize the system capacity based on the CQI(Channel Quality Information). Firstly, power level is decided to each sub-channels with received feedback signal to noise ratio(SNR). In the second step, sub-carriers are allocated according to modulation type. Simulation results show that the proposed algorithm achieves a better performance than conventional algorithm in terms of capacity.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.3
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• pp.13-18
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• 2005

This paper presents a design of a multi-objective $H_2/H_{\infty}$ controller of an inverted pendulum with polytopic model by the stabilizing regulator and tracking performances. Multi-objective controllers are designed for polytopic models by the LMI design technique with convex algorithms. It is observed that the inverted pendulum controlled by any controller designed for each polytopic model is stably restored to the vertical angle position for initial values of larger tilt angles.

• Korean Journal of Adult Nursing
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• v.27 no.5
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• pp.604-611
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• 2015

Purpose: Knowledge, clinical reasoning, and self-confidence are the basis for undergraduate education, and determine students' level of competence. The purpose of this study was to assess the effects of the addition of a one-time simulation experience to the didactic curriculum on nursing students' knowledge acquisition, clinical reasoning skill, and self-confidence. Methods: Using a quasi-experimental crossover design consisted of intervention and wait-list control groups. Participants were non-randomly assigned to the first intervention group (Group A, n=48) or the wait-list control group (Group B, n=46). Knowledge level was assessed through a multiple choice written test, and clinical reasoning skill was measured using a nursing process model-based rubric. Self-confidence was measured using a self-reported questionnaire. Results: Results indicated that students in the simulation group scored significantly higher on clinical reasoning skill and related knowledge than those in the didactic lecture group; no difference was found for self-confidence. Conclusion: Findings suggest that undergraduate nursing education requires a simulation-based curriculum for clinical reasoning development and knowledge acquisition.