• Journal of Astronomy and Space Sciences
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• 제38권3호
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• pp.165-173
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• 2021

Apophis is a near-Earth object with a diameter of approximately 340 m, which will come closer to the Earth than a geostationary orbit in 2029, offering a unique opportunity for characterizing the object during the upcoming encounter. Therefore, Korea Astronomy and Space Science Institute has a plan to propose a space mission to explore the Apophis asteroid using scientific instruments such as a laser altimeter. In this study, we evaluate the performance metrics of a laser altimeter using a pseudorandom noise modulation technique for the Apophis mission, in terms of detection probability and ranging accuracy. The closed-form expression of detection probability is provided using the cross correlation between the received pulse trains and pseudo-random binary sequence. And the new ranging accuracy model using Gaussian error propagation is also derived by considering the sampling rate. The operation range is significantly limited by thermal noise rather than background noise, owing to not only the low power laser but also the avalanche photodiode in the analog mode operation. However, it is demonstrated from the numerical simulation that the laser altimeter can achieve the ranging performance required for a proximity operation mode, which employs commercially available components onboard CubeSat-scale satellites for optical communications.

• 한국컴퓨터정보학회논문지
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• 제24권9호
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• pp.127-134
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• 2019

The purpose of this study is to understand the purchasing intentions of Chinese consumers to Huawei and other domestic brands in the context of the current Sino-US trade war. Taking the mass consumers as the research object, this paper designs Likert five-level scale to investigate consumers' purchase intention of domestic products in the future, and uses SPSS 23.0 and AMOS 23.0 statistical software to analyze and process statistical data. Using questionnaire survey and exploratory factor analysis, this paper constructs a model to analyze the impact of consumer ethnocentrism on consumers' purchase intention. By summarizing the overall purchasing intention of consumers, it is concluded that the development of domestic brands in the context of trade war is facing difficulties and challenges in the future, but at the same time, we must seize the opportunity of consumers' ethnocentrism under this background to positively influence their purchasing intention, make up for shortcomings, eliminate overcapacity, and seek greater development through technological innovation.

• Environmental Engineering Research
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• 제24권2호
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• pp.279-288
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• 2019

To obtain insightful knowledge of geochemical process controlling fluoride enrichment in groundwater of the villages near Shilabati river bank, West Bengal, India, multivariate statistical techniques were applied to a subgroup of the dataset generated from major ion analysis of groundwater samples. Water quality analysis of major ion chemistry revealed elevated levels of fluoride concentration in groundwater. Factor analysis (FA) of fifteen hydrochemical parameters demonstrated that fluoride occurrence was due to the weathering and dissolution of fluoride-bearing minerals in the aquifer. A strong positive loading (> 0.75) of fluoride with pH and bicarbonate for FA indicates an alkaline dominated environment responsible for leaching of fluoride from the source material. Mineralogical analysis of soli sediment exhibits the presence of fluoride-bearing minerals in underground geology. Hierarchical cluster analysis (HCA) was carried out to isolate the sampling sites according to groundwater quality. With HCA the sampling sites were isolated into three clusters. The occurrence of abundant fluoride in the higher elevated area of the observed three different clusters revealed that there was more contact opportunity of recharging water with the minerals present in the aquifer during infiltration through the vadose zone.

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.167-174
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• 2022

Vehicular Ad hoc Networks are considered as special kind of Mobile Ad Hoc Networks. VANETs are a new emerging recently developed, advanced technology that allows a wide set of applications related to providing more safety on roads, more convenience for passengers, self-driven vehicles, and intelligent transportation systems (ITS). Delay Tolerant Networks (DTN) are networks that allow communication in the event of connection problems, such as delays, intermittent connections, high error rates, and so on. Moreover, these are used in areas that may not have end-to-end connectivity. The expansion from DTN to VANET resulted in Vehicle Delay Tolerant Networks (VDTN). In this approach, a vehicle stores and carries a message in its buffer, and when the opportunity arises, it forwards the message to another node. Carry-store-forward mechanisms, packets in VDTNs can be delivered to the destination without clear connection between the transmitter and the receiver. The primary goals of routing protocols in VDTNs is to maximize the probability of delivery ratio to the destination node, while minimizing the total end-to-end delay. DTNs are used in a variety of operating environments, including those that are subject to failures and interruptions, and those with high delay, such as vehicle ad hoc networks (VANETs). This paper discusses DTN routing protocols belonging to unicast delay tolerant position based. The comparison was implemented using the NS2 simulator. Simulation of the three DTN routing protocols GeOpps, GeoSpray, and MaxProp is recorded, and the results are presented.

• 적정기술학회지
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• 제6권2호
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• pp.103-114
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• 2020

적정기술은 해외 개발도상국 지역 주민의 환경과 수요에 맞추어 서로 다른 국가 및 국민들이 상호작용하는 공공외교의 틀로 비추어 볼 수 있을 것이다. 한국에서는 2016년에 공공외교법이 발효 되는 등 비교적 최근에 이르러서야 정부, 기관, 국민들이 참여하고 있으며, 한류 등 문화 분야에 집중되어 있는 현황이다. 이와 관련하여 해외 주요국과 한국의 과학기술 공공외교 현황을 비교해보고, 한국의 강점 및 발전 가능성, 평가 관리에 대해서 고찰해 보고자 한다. 적정기술과 과학기술을 공공외교의 틀에서 접근한다면 한국 및 현지의 각 참여자들이 유기적으로 협력을 도모할 수 있는 기회가 될 수 있을 것이다.

• 한국버섯학회지
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• 제20권4호
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• pp.193-198
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• 2022

The biological efficiencies of promising Pleurotus spp. were evaluated. Pleurotus ostreatus, Pleurotus tuberregium,and Pleurotus sajor-cajuwere investigated at temperatures of 22℃, 20℃, and 18℃ to determine their ability to adapt to temperatures that are likely to be found in subtropical regions. The experiment was conducted using a substrate comprising Popular sawdust 60% + cotton seed 20% + beet pulp 20% under a relative humidity of 65%. The results indicated that there were significant differences in terms of biological efficiency between the species: P. tuber regium 128.84% at 22℃, P. ostreatus 108.41% at 22℃, and P. sajor-caju is 80% at 20℃. The common temperatures at which all species showed the highest biological efficiencies were 22℃ and 20℃. Therefore, the production of the evaluated species was equal to or surpassed biological efficiencies reported in tropical environments, thereby demonstrating a potential opportunity to adapt to tropical environments without compromising quality standards.

• Journal of Animal Science and Technology
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• 제65권3호
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• pp.490-510
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• 2023

Feed safety is needed to produce and provide safe animal feeds for consumers, animals, and the environment. Although feed safety regulations have been set for each country, there is a lack of clear feed safety regulations for each livestock. Feed safety regulations are mainly focused on heavy metals, mycotoxins, and pesticides. Each country has different safe levels of hazardous materials in diets. Safe levels of hazardous materials in diets are mostly set for mixed diets of general livestock. Although there is a difference in the metabolism of toxic materials among animals, the safe level of feed is not specific for individual animals. Therefore, standardized animal testing methods and toxicity studies for each animal are needed to determine the correct safe and toxic levels of hazardous materials in diets. If this goal is achieved, it will be possible to improve livestock productivity, health, and product safety by establishing appropriate feed safety regulations. It will also provide an opportunity to secure consumer confidence in feed and livestock products. Therefore, it is necessary to establish a scientific feed safety evaluation system suitable for each country's environment. The chance of outbreaks of new hazardous materials is increasing. Thus, to set up appropriate toxic levels or safe levels in feed, various toxicity methods have been used to determine toxic levels of hazardous materials for humans and animals. Appropriate toxic testing methods should be developed and used to accurately set up and identify toxicity and safe levels in food and feed.

• Educational Technology International
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• 제6권1호
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• pp.103-119
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• 2005

This study investigated to designand implement web-based collaborative learning system Co-Net and map out students' learning procedure using the system, based upon Student Team Achievement Division (STAD Slavin, 1990, 1996). There are technical process and instructional considerations to be made during the design process. The former are those that concern equipment requirements and specifications and include Ease of Use, Speed of Access, and Flexibility. On the other hand, instructional considerationsare concerned with the delivery and access of instructional materials and their outcomes on learners. They are cooperative interactions within groups and group heterogeneity, learner control, group incentives, individual accountability, equal opportunity for earning high scores and contributing to group effort, task specialization, and competition among groups. A web site for a virtual learning environment designed and built by the authors and known as Co-Net is then explained along with the whole process learners inside the environment. The main page of Co-Net consists of 15 menus to implement cooperative learning process. The cooperative learning activities using 15 menus are composed of six phases (1) preparation of the new knowledge (2) presentation of the new knowledge (3) knowledge assimilation and application (4) team and individual evaluation (5) team and individual recognition Throughout the five phases, the appropriate use of cooperative learning techniques has been shown to have both academic and social benefits to learners.

• 농촌계획
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• 제30권2호
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• pp.69-77
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• 2024

As impervious area increases due to urbanization, rainfall on the impervious area does not infiltrate into the ground, and stormwater drains quickly. Low impact development (LID) practices have been suggested as alternatives to infiltrate and store water in soil layers. The practices in South Korea is applied to urban development projects, urban renewal projects, urban regeneration projects, etc., it is required to perform literature research, watershed survey, soil quality, etc. for the LID practices implementation. Prior to the LID implementation at fields, there is a need to simulate its' effect on watershed hydrology, and Storm Water Management Model (SWMM) provides an opportunity to simulate LID practices. The LIDs applied in South Korea are infiltration-based practices, vegetation-based practices, rainwater-harvesting practices, etc. Vegetation-based practices includes bio-retention cell and rain garden, bio-retention cells are mostly employed in the model, adjusting the model parameters to simulate various practices. The bio-retention cell requires inputs regarding surface layer, soil layer, and drain layer, but the inputs for the drain layer are applied without sufficient examination, while the model parameters or inputs are somewhat influential to the practice effects. Thus, the approach to simulate vegetation-based LID practices in SWMM uses was explored and suggested for better LID simulation in South Korea.

• 한국간호교육학회지
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• 제9권1호
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• pp.41-50
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• 2003

Purpose: Nursing education should be considered the training for professional nurses who can deliver high quality care to meet the needs of health consumers. This study was aimed at evaluation on practice satisfaction of nursing student in the community. Method: The data was collected from 107 students at 4 colleges and 72 students at 3 universities in Daegu city from March 1st to June 30th, 2001. This study was investigated by the questionnaire which was consisted of general characteristics, recognition of nursing and practice satisfaction. The questionnaire of practice satisfaction used in this study was modified from Lee, S.J.(1980)'s and Park(1994)'s questionnaire. The data was analyzed by SAS(ver. 6.12) program and statistical methods used were mean, standard deviation and ANOVA(analysis of variables). Result: The findings of this study were as follows: 1. Students showed that nursing is a kind of activities for promotion of health, prevention of disease, recovery of health and relieving of pain in the recognition of the nursing. 2. Students showed that the community- practice gives an opportunity to learn the relationship with health team for the solution of trouble patients in the recognition for the necessity of the community-practice. 3. In the practice satisfaction, students gained high score in evaluation, but especially low score in instruct of the community-practice. 4. The general characteristics which affected practice satisfaction were grade, motivation of nursing selection and duration of practice in the community-practice. Conclusion: As theses results it was necessary to prepare the programed and developed practice-education in the community.