• Journal of Advanced Navigation Technology
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• v.18 no.4
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• pp.347-352
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• 2014

In this paper, we propose a Markovian queueing model(M/M/1)-based call admission control to reduce forced terminating rate of non-real secondary user's call for Multi-services Cognitive Radio Networks. A existing control has a problem that the forced terminating rate increases because of adopting a policy of spectrum priority allocation to real calls. In our scheme the rate can be reduced as the call that has no useful spectrum waits in a queue until getting an available spectrum. Our scheme use a neural-net based prediction of primary user's reappearance. Through the simulation, we analysis the call forced terminating rate, access delay and spectrum utilization efficiency, and then show that our scheme can more reduce the forced terminating rate of the call, compared to that of the existing algorithm.

• Journal of Elementary Mathematics Education in Korea
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• v.17 no.2
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• pp.207-223
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• 2013

Teachers unfold a series of timeless mathematical symbols such as 5+2=7 in time by verbalizing the symbols in classrooms. A number sentence 5+2=7 is read in Korean as '5 더하기 2는(five plus two) 7과(seven) 같다(equals). Unlike in English, 5+2 and 7 are read first before the equal sign in Korean. This sequence of reading in Korean conflicts with the conventional linguistic sequence of writing from left to right. Ways of resolving the discrepancy between reading and writing sequences can make a difference students' understanding of the equal sign. Students would be in danger of perceiving the equal sign as an operational symbol, if a teacher resolves the discrepancy by subordinating reading sequence to linguistic convention of writing. This way of resolving results in the undesired phenomenon of changing the reading expressions in Korean elementary math textbook which represent relational notion of the equal sign into other reading expressions that represent operational notion of it. For understanding of relational notion of the equal sign, the discrepancy should be resolved by changing writing sequence in accordance with reading sequence. In addition, teaching of verbalizing the equal sign should be integrated with teaching of verbalizing inequality signs.

• Journal of Life Science
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• v.19 no.11
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• pp.1562-1567
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• 2009

Heavy metal contamination levels in Andong reservoir and Imha reservoir were measured with heavy metal contents in both water and sediment, and analyzed with heavy metal accumulation level in inhabitant fish, Carassius auratus, using an inductively coupled plasma spectrometer and an atomic absorption spectrometer. High levels of heavy metal contents in water, sediment and the tissues of C. auratus were detected. Likewise, relatively high levels of As were detected in water and sediment from Andong reservoir. In addition, higher levels of Cr, Cu, Cd and As content were detected in muscle and bone tissues of fish from Andong reservoir than those from Imha reservoir. As a result, the heavy metal content of water, sediment and inhabitant fish, C. auratus, in Andong reservoir was higher than Imha reservoir. We proposed that heavy metal contamination in water and inhabitant fish is attributed to various metals derived from abandoned mines and farmlands that are upstream of Andong reservoir.

• The Journal of the Korea Contents Association
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• v.19 no.7
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• pp.281-290
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• 2019

With the goal of enforcing a municipal police system in a national scale starting from 2021, the proposal for introducing municipal police system is promoted and the private security is spotlighted as the measure for supplementing the issues for municipal police system. To solve this issue, the method of promoting and actively utilizing the private security which served as an assistant for security service into the cooperator for security service is suggested as a practical method. To analyze how police's favorable attitude toward introduction of municipal police system influence on the favorable trust toward private security system, this study conducted a survey on front line police officers and analyzed the collected data through statistical technique. As a result, the police officers favorable to introduction of municipal police system also showed positive attitude toward private security and machine security. However, the survey didn't provide significant result on labor expense. In order for the private security service to be accepted as the cooperator for security service, it is necessary to solve the labor expense issue and strengthen trust on machine security.

• The Journal of the Korea Contents Association
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• v.21 no.7
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• pp.660-670
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• 2021

In this study we examined the relationships between an elementary schoolchild' cognition, attitude, and the frequency and amount of kimchi consumed. Referring to previous studies, we define cognition as being composed of benefit, identity, and globalization. We examined how each cognition affected attitude, and how attitude affected amount of kimchi consumed, on a scale of preference or non-preference. We confirmed that the 'identity' cognition and 'globalization' cognition of kimchi have a positive effect on 'favorable attitude'. The 'benefit' cognition did not have a significant effect on 'favorable attitude', but it did have a positive effect on 'identity' and 'globalization', which had a significant effect on 'favorable attitude'. We also confirmed that 'favorable attitude' has a positive effect on the 'frequency of kimchi intake' and 'amount of kimchi intake'. Given these results, it is necessary to develop and supply the educational contents that stimulate the identity and globalization of kimchi in order to improve children's intake of kimchi, emphasizing the benefits of consuming kimchi.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.243-243
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• 2021

담수호는 방조제 건설 및 담수화를 통해 다양한 용수공급을 위해 개발된 수자원으로서 담수화된 수자원은 농업용수로 활용이 가능하다. 특히 간월호의 경우, 담수호 주변이 주로 농경지로 이루어져 있으며, 담수화된 수자원은 농업용수를 공급하기 위해 활용되고 있다. 따라서 간월호의 수자원 관리를 위한 장기적인 계획 수립을 위해서는 간월호의 주요 용수공급 대상이 되는 농경지 물수요량의 미래 변화에 대한 평가가 우선되어야 한다. 최근 IPCC (Intergovernmental Panel on Climate Change)에서는 기존 대표농도경로에 사회·경제 조건을 추가하여 공동 사회-경제 경로 (SSP, Shared Socioeconomic Pathways)라는 개념을 새롭게 제안하였으며, 이를 기반으로 6차 평가보고서 (6th Assessment Report, AR6)를 발간한 바 있다. 본 연구에서는 CMIP6 기후변화 자료를 기반으로 한 기후변화 자료를 통해 담수호 유역의 농업용수 수요량 변화를 평가하였으며, Makov chain 모형을 이용한 토지이용변화 자료를 검토하여 기후변화 뿐만 아니라 토지이용변화를 함께 고려한 미래 농업용수 수요량 변화 평가를 수행하였다. 이를 통해 CMIP6 시나리오별 미래 농업용수 수요량 변화를 검토하고, 현재 간월호의 용수공급 능력과 비교를 통해 간월호의 수자원 관리 능력을 평가하는 것이 본 연구의 목적이다.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.60-64
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• 2005

STSAT-2 will demonstrate the scientific mission(acquisition of brightness temperature of the earth at 23.8 GHz and 37 GHz) and spacecraft technologies(laser ranging, frame-type satellite structure, Dual-head star tracker, CCD sun sensor, pulsed plasma thruster, etc.). In this paper STSAT-2 satellite system is described. It includes the definition of the system and the overview of payloads and BUS.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1691-1695
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• 2006

합천호의 총유역면적은 $925km^2$이다. 합천호 유역내 주요 하천은 황강본류, 논덕천, 사천천, 유전천 및 하금천이다. 유역면적을 살펴볼 때 합천호 강우유출의 86.3 %는 황강본류 유역으로부터 유입되고 약 13.7 %만이 그 외의 하천들로부터 유입되는 것으로 판단된다. 본 연구에서는 강우유출이 성층화된 합천호의 수온분포에 미치는 영향을 2차원 수치모의를 통하여 검토하였다. 유입지천의 수온은 성층화된 여름철 저수지의 거동에 큰 영향을 미친다. 따라서 합천호 유입지천 3개 지점에 수온계를 설치하여 수온변화를 조사하였다. 2차원 수치모의결과에 의하면, 비강우시의 경우에는 합천호의 수온성층현상을 보이는 구간은 합천댐으로부터 19 km지점까지로 나타났으며, 강우시 유입유량의 증가로 인하여 수온성층현상을 보이는 구간은 감소하는 것으로 나타났다. 이는 강우유출이 증가함에 따라서 유입수의 운동량이 증가하기 때문에 저수지의 수온성층현상의 영향을 상대적으로 작게 받기 때문으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2158-2162
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• 2009

본 연구에서는 실측자료와 염분수지 계산식을 이용하여 이원 담수호의 염도변화를 모의하였다. 이원담수호는 충남 태안군 원북면 방갈리 민어도에서 이원면 관리 반금봉을 연결하며, 간척농지 개발사업은 1990년에 착공하여 1997년 최종물막이 공사가 완료되었다. 담수호의 염도변화를 모의하기 위한 유입량과 유출량자료는 배수갑문 운용자료와 일별 수위자료로부터 산정하였다. 유출량은 내 외수위 조건에 따라 계산식을 적용하였으며, 이와 함께 배수갑문 역유입량, 방조제 누수량, 호저토 확산 염분량을 계산하여 염분수지식에 적용하여, 2006년부터 2008년까지의 염도변화를 모의하였다. 모의치를 실측치와 비교한 결과, 결정계수($R^2$)가 0.95${\sim}$0.98의 값을 보였다. 이와 함께 RMSE를 통해 그 적용성을 검토하여 3년간의 이원 담수호의 염도변화를 모의하였다.

• Journal of Korea Water Resources Association
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• v.30 no.3
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• pp.293-301
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• 1997

The major objective of this study is to evaluate the water balance of the Kumgang estuary barrage, one oof the regions with the most complex water utilization system. For the purpose of present study, two approaches are proposed which consider both the natural flow and low flow conditions, respectively. In order to make the evaluation of the low flow sequences, the flood frequency of the sequences was removed. According to the results, water deficiency is expected on the target year of 1996 in case of low inflow.