• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2658-2679
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• 2018

This paper proposes a novel Random Scheduling Algorithm based on Subregion Coverage (RSASC), to solve the SET K-cover problem (an NP-complete problem). SET K-cover problem distributes the set of sensors into the maximum number of mutually exclusive subsets (MESSs) in such a way that each of them can be scheduled for lifetime extension of WSN. Sensor coverage divides the target region into different subregions. RSASC first sorts the subregions in the ascending order concerning their sensor coverage. Then, it forms the subregion groups according to their similar sensor coverage. Lastly, RSASC ensures the K-coverage of each subregion from every group by randomly scheduling the sensors. We consider the target-coverage and area-coverage applications of WSN to analyze the usefulness of our proposed RSASC algorithm. The distinct quality of RSASC is that it utilizes less number of deployed sensors (33% less) to form the optimum number of MESSs with the higher computational speed (saves more than 93% of the time) as compared to the existing three algorithms.

• 한국치위생학회지
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• 제15권6호
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• pp.1107-1116
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• 2015

Objectives: The purpose of this study was to examine awareness and satisfaction toward health insurance coverage of scaling. Methods: A self-reported questionnaire was completed by 221 patients receiving scaling service from July to August, 2014. The informed consent was approved after the explanation of purpose of the study. The questionnaire consisted of general characteristics of the subjects, awareness toward health insurance coverage of scaling, scaling service covered by health insurance, and satisfaction with health insurance service. Results: Those recognizing the health insurance service extension accounted for 87.3 percent and 67.4 percent answered that the appropriate coverage age would be 20 years old. The recommendable frequency of scaling was once a year and this accounted for 49.3 percent. Fifty percent of the subjects thought health insurance coverage of scaling would be reasonable and 34.8 percent acquired the information from mass media. The most common service providers were dental hygienists and the length of service was from 20 to 30 minutes. The contents of service included scaling service, toothbrushing method, and oral care. The satisfaction was 4.39 points. Conclusions: The health insurance coverage of scaling will improve the oral health and quality of life in Korean adults. So the government should try to extend the scaling coverage by health insurance and the frequency of scaling.

• 농업과학연구
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• 제50권3호
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• pp.427-435
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• 2023

This study was conducted to evaluate the spraying performance according to the flight conditions of agricultural drones for the development of a variable control system. The analyzed flight conditions comprised six factors: spraying direction, flight speed, altitude, wind speed, wind direction, and rotor rotational speed. The ratio of the area sprayed on the water-sensitive paper was used as the coverage, and the distribution and amount of the coverage were evaluated. The coverage distribution based on the distance from the drone was used to evaluate a spray pattern, and the distribution was expressed as a Gaussian function approximation. In addition, the probability distribution based on coverage was expressed as the cumulative probability via Gamma function approximation to analyze the spraying efficiency in the target area. The results showed that the averaged coverage decreased significantly as the flight speed and wind speed increased, and the wind direction changed the spray pattern without a coverage decrease. This study contributes to the development of a control technique for the precision control system of agricultural drones.

• 한국ITS학회 논문지
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• 제8권1호
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• pp.30-36
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• 2009

도심지역에서 사용되는 DSRC 통신시스템은 노변기지국과 차량간 100미터의 통신거리를 갖고 있으며, 이 특성을 이용하여 DSRC시스템에서 RSE(Road Side Equipment)는 차량으로부터 교통정보를 수집하거나 차량에 교통정보를 제공한다. 그러나 고속도로상에서 100미터 통신범위를 갖는 RSE를 사용하는 것은 장비가격 및 설치비가 고가이어서 현실적으로 많은 어려움이 있다. 본 논문에서는 RSE의 표준 셀 범위를 100미터에서 300미터로 확장하고 차량단말기가 RSE와 통신할 수 없는 불감지역을 Cover 하기 위하여 Fixed Relay를 도입하였으며, 이로 인해 Fixed Relay를 사용하는 것이 RSE 만을 사용하는 것 보다 더 경제적인 것을 보인다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권10호
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• pp.5989-5993
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• 2013

Background: Radiation therapy is the mainstay of treatment for nasopharyngeal carcinoma. Importance of tumor coverage and challenges posed by its unique and critical location are well evident. Therefore we aimed to evaluate our radiation treatment plan through dose volume histograms (DVHs) to find planning target volume (PTV) dose coverage and factors affecting it. Materials and Methods: This retrospective study covered 45 histologically proven nasopharyngeal cancer patients who were treated with definitive 3D-CRT and chemotherapy between Feb 2006 to March 2013 at the Department of Oncology, Section Radiation Oncology, Aga Khan University Hospital, Karachi, Pakistan. DVH was evaluated to find numbers of shrinking field (phases), PTV volume in different phases and its coverage by the 95% isodose lines, along with influencing factors. Results: There were 36 males (80%) and 9 females (20%) in the age range of 12-84 years. Stage IVA (46.7%) was the most common stage followed by stage III (31.1). Eighty six point six-percent received induction, 95.5% received concurrent and 22.2% received adjuvant chemotherapy. The prescribed median radiation dose was 70Gy to primary, 60Gy to clinically positive neck nodes and 50Gy to clinically negative neck regions. Mean dose to spinal cord was 44.2Gy and to optic chiasma was 52Gy. Thirty seven point eight-percent patients completed their treatment in three phases while 62.2% required four to five phases. Mean volume for PTV3 was $247.8cm^3$ (50-644.3), PTV4 $173.8cm^3$ (26.5-345.1) and PTV5 $119.6cm^3$ (18.9-246.1) and PTV volume coverage by 95% isodose lines were 74.4%, 85.7% and 100% respectively. Advanced T stage, intracranial extension and tumor volume > $200cm^3$ were found to be important factors associated with decreased PTV coverage by 95% isodose line. Conclusions: 3D CRT results in adequate PTV dose coverage by 95% isodose line. However advanced T stage, intracranial extension and large target volume require more advanced techniques like IMRT for appropriate PTV coverage.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2007년도 추계학술대회 및 정기총회
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• pp.316-321
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• 2007

The hierarchical covering location problem emphasizes the issue of locating of hierarchical facilities in order to maximize the number of customers that can be covered. In the classical HCLP(Hierarchical Covering Location Problem), it is assumed that the customers are covered completely if they are located within a specific distance from the facility, and not covered otherwise. The generalized HCLP is introduced that the coverage of customers is measured to be any real value rather than 0 or 1, where the service level may decrease according to the distance. Mixed integer programming formulation for the generalized HCLP is suggested with a partial coverage of service. Solutions are found using OPL Studio, and are evaluated for various cases.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제4권9호
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• pp.425-430
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• 2015

센서 레지스트리 시스템(Sensor Registry System, SRS)은 이기종 센서 네트워크 환경에서 센서 데이터의 즉각적 활용 및 끊김 없는 해석을 위해 사용자에게 센서 메타데이터를 제공한다. 하지만 기존 SRS는 네트워크 연결이 지원되지 않거나 신호가 불안정한 경우에 센서 메타데이터를 안정적으로 제공할 수 없다. 이 논문에서는 이러한 문제를 해결하기 위해, 네트워크 커버리지 정보를 이용한 센서 레지스트리 시스템 확장 방법을 제안한다. 제안 방법은 예측한 경로와 네트워크 커버리지에 대한 오픈 데이터(통신사, 신호 강도, 통신 타입)를 이용하여 사용자가 불안정한 네트워크 지역에 도착하기 전에 해당 지역의 센서 메타데이터를 추가로 송신한다. 이 논문에서 제안한 확장된 SRS는 사용자에게 보다 안정적으로 센서 메타데이터를 제공함으로써 응용서비스의 품질을 향상시킨다.

• 한국통신학회논문지
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• 제34권1A호
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• pp.18-26
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• 2009

기존의 무선 통신 시스템에서 신호의 수신 범위를 늘리고 수율을 증가시키기 위해 릴레이를 이용하는 방식이 다양하게 고려되고 있다. 하지만, 릴레이를 이용하는 방식은 변조 방식에 따라 제한된 수신 범위를 갖고 릴레이가 추가됨에 따라 추가적인 시간슬롯이 요구되는 단점이 있다. 본 논문에서는 계층적 변조방식과 두 개의 분산된 릴레이를 결합하여 2 홉 시스템을 구현하며, 수율과 최대 전송가능 영역을 모두 증대시킬 수 있는 방식을 제안한다. 제안된 방식에서는 단말의 위치에 따라 다른 레벨을 가지는 데이터의 수신이 가능함에 따라 최대수신가능 영역이 증대되고 수율이 약 2배 증가되는 이득을 얻을 수 있었다.

• 한국사회복지학
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• 제45권
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• pp.72-100
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• 2001

Despite the rapid expansion of social security coverage in the 1990s, many wage earners in Korea, especially the majority of the nonstandard workforce are excluded in the social insurance programs. In this regards, the purpose of this paper is to analyze causes of the exclusion of nonstandard workers to the social insurance scheme and to suggest the feasible policy options. Through this paper, four arguments are addressed as follows. First, the main issue for exclusion from coverage of those workers is that they have no entitlement to social insurance. This is not an issue of that they fall below hours or income thresholds for the entitlement Second, the top-down process of the extension in the Korean social insurances have divided the wage earners into two groups, the insider (the included) and the outsider (the excluded). Many nonstandard workers belong to the latter category. Third, the social insurance systems have been designed for the regular workers who were characterized by a full-time with some degree of stability. Reform designed to cope with the growth of nonstandard workers must build on the existing structure of social insurance. Finally, the governance capacity by social security administration body must be improved in order to provide a basic social protection for those workers. For that, four separated social insurance administration bodies could be unified to one administrative body, or tax and contribution of social insurance could be collected by one integrated administration body, the National Tax Service.

• 한국토양비료학회지
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• 제44권4호
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• pp.534-538
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• 2011

One of the problems for cultivating crops in the mountainous highland is soil erosion and nutrients runoff. Alternative cropping ways were searched to reduce soil erosion and to ensure farm income in the mountainous highland agricultural region. Three edible wild plants including goatsbeard, Korean thistle, and aster, were selected to test as alternative crops to reduce soil erosion in mountain agriculture of highland area. In the first year, the soil losses from the alternative cropping were 26 to 63 percents of the soil loss from summer radish cultivated by conservation tillage with contour and plastic film mulching. The relative soil losses in the second year ranged from 2.8 to 5.5 percents in comparison with radish cultivation. Rapid surface coverage contributed to successive soil loss protection by these alternative crops. Farm net profit of these crops was greater than that of radish. Monitoring of yields of Korean thistle or aster for further experiments, however, might be necessary for economic cultivation due to yield reduction caused by consecutive production.