• Electronics and Telecommunications Trends
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• v.26 no.2
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• pp.14-24
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• 2011

AIP를 설정하는 방법에서는 국가에 따라 일부 차이를 보이고 있지만, 본 고에서는 종주국이라 할 수 있는 영국에서의 최소비용대체법을 사용한 한계가치 산출방식을 사용하여 2011년에 주파수 재할당 대상이 되는 800MHz 대역을 대상으로 모형을 제시하고 적용결과를 분석하였다. 먼저 추가주파수를 사용하는 시스템과 주파수 대신 기지국 투자를 추가하는 시스템의 비교를 통하여 두 시스템간 셀간 면적비를 기준으로 한계가치를 도출하는 모형을 제안하고, 새로 도입될 기술인 LTE의 시스템 성능을 평가할 수 있는 시스템 레벨 시뮬레이터를 3GPP에서 제안하고 있는 이동통신 시스템 환경 및 요구조건에 따라 제작하였으며, 이 시뮬레이터를 바탕으로 시스템 도입 지역 또는 운영 주파수 대역에 따라 시뮬레이션을 통하여 시스템 용량을 산출하였다. 마지막으로 제안된 한계가치 모형과 시뮬레이션 결과를 결합하여 최종적으로 한계가치 산정의 기준이 될 추가기지국의 규모를 추정할 수 있는 모델을 제시하였다.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.8-13
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• 2001

다 단계 의사결정지원시스템, AHP(Analytic Hierarchy Process)는 다수 대안에 대하여 다 면적인 평가기준과 다수 주체에 의한 의사결정을 위해 설계된 의사결정지원방법의 하나이다. AHP 시스템은 먼저 주어진 시스템을 구성하고있는 요소를 세분하고 그 분할된 요소를 계층적으로 구성하며 다음으로 계층간 각 레벨에 있는 요소의 상대적 중요도에 대한 판단을 종합하는 과정을 거친다. 본 연구에서는 이러한 AHP방법을 실용화하기 위하여 사용자가 Web기반에서 활용하기 쉽도록 GUI-tyre 프로그램을 개발하고 이를 검증하였으며 예제를 들어 보였다. 본 연구에서 개발한 소프트웨어는 크게 다음과 같이 3 가지 구조로 구성하였다. 단계 1 : 대안 평가의 아이디어 창출 단계(Brainstorming), 단계 2 : 다 단계, 다 기준 의사결정지원시스템(AHP), 단계 3 우선 순위 종합모델(MRM)

• Journal of Korean Society of Forest Science
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• v.102 no.4
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• pp.608-616
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• 2013

The objective of this study was to suggest contingent valuation method, simple random sampling method, systematic sampling method, maximum practice area method, and overlay practice area method as the estimation methods for forest management area to estimate carbon dioxide sink by forest management as stated in Article 3.4 of the Kyoto Protocol. A case study for Chungcheongbuk-do was performed using maximum practice area method which was thought of as the most rational method within MRV(Measurable, reportable and verifiable). The forest management ratio was defined as forest management area over the total forest area. Based on the definition of forest management activity, forest area was divided into practice forest land and non-practice forest land. The area of forest mangement for practices was based on the 'National Forest Management Information System' and the history of practices from the 'Proposals on Private Management Information Database'. The area of forest management for non-practices was based on the public used forest land from 'Categorial map of forest land'. It was shown that the forest management area of Chuncheongbuk-do was 115,566 ha for practice forest land, and 131,008 ha for non-practice forest land. The forest managent ratio was 49.7% of the total forest area of 495,806 ha. This study made possible to the estimation of the forest management ratio under Kyoto Protocol, and had an advantage in searching for a practical method of forest management plan in which the forest management ratio could be enhanced.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.375-384
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• 2005

The effects of bar deformation properties on bond of steel reinforcing bars to concrete are experimentally studied to predict the bond strength. Based on the previous research about high relative rib area, bond strength between reinforcing bars and concrete can be improved by the control of rib height and spacing. But, the equations in Korean code provisions to estimate development and splice length do not include these specifications of reinforcing bars. So the purpose of this paper is to determine the effect of relative rib area to the bond strength. This paper describes 2 kinds of experimental researches. Thirty beam-end specimens were tested to investigate the effects of bar size and relative rib areas ranging from 0.112 to 0.162. And, twelve lap-splice beam specimens were tested to the same variables. Each test results are normalized and compared with the proposed equations of ACI 408 committee. The results show that bond strength is increased as bar size and the relative rib area(Rr) increase. The distribution of flexural cracks and failure aspect do not appear to be affected by $R_r$.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.1-14
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• 1996

Especially in the case of a full form ship, the stability on course can be considered to become severest among 4 items of criteria in Interim Standards for Ship Maneuverability adopted by IMO in 1993. The purpose of this study is to find some ideas for the improvement of stability on course through changes in rudder area with reference to span distance. In this paper, we established the formula on the relation between the experimental constants relevant to rudder normal force and hydrodynamic derivatives of hull-propeller-rudder system. We carried out various kinds of captive model test relevant to rudder normal force etc., and evaluated hydrodynamic derivatives of hull-propeller-rudder system, and analyzed the stability on course with the parameter of changes in rudder area. Furthermore, we also discussed effects of changes in rudder area on maneuvering performance including stability on course, based on computer simulation. As a result, it is clarified that there is a possibility that stability on course may become bad through an increase of rudder area. The reason for the bad stability on course is that the void space between the upper edge of rudder and the lower part of stern overhang decreases. This space change exerts a great influence on straightening coefficient of incoming flow to rudder in maneuvering motion, which has close relation to stability on course.

• The Journal of Sustainable Design and Educational Environment Research
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• v.15 no.1
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• pp.19-29
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• 2016

This study aims to find a direction for desirable space organization in future Korean kindergartens by analyzing the current status of space organization in Japanese kindergartens. This study includes comparisons and analyses of Korean and Japanese curricula, facility standards on the national level and standards of national subsidy, current numbers of kindergarteners and preschoolers, and changes in kindergarten facilities over the last 5 years. Six kindergartens each in Korea and Japan, which were constructed after 2011 or are recommended as being good in space organization and kindergarten planning, are selected. The contents of space organization analysis are 'entry and placement, outdoor space', 'space program,' and 'plan design and organization of unit space'. In conclusion, in terms of space organization, Korean and Japanese kindergartens are very similar to each other. However, Japanese kindergartens have more outdoor space about $9.75m^2$ and lot area about $11.89m^2$ than Korean kindergartens. The extra space was used to educate students in various contents regarding social network and physical activity. Furthermore, in Japan, special spaces such as "atelier classes" and "PTA" were used for various types of education. Based on the results of the study will be developed, such as specific models and guidelines for the improvement of facilities Korea kindergarten.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.220-227
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• 1997

Water deficit stress during early soybean[Glycine max (L.) Merrill] growth stage is the most important environmental factor limiting productivity. Eight soybean genotypes were grown in replicated pot under well-watered(control: near 0 bar) and drought(-5 and -10 bars) conditions. Soybean plants were subject to drought stress for 20 days at 10 days after seed emergence. Significant genotypic variation was observed for leaf area(LA) and total dry weight (TDW). At the end of water stress, LA and TDW of Hwanggeumkong and Paldalkong, which had large LA in the non-stressed control, were more sensitive to water stress than those of the other cultivars, while those of Suwon 93 with small LA were insensitive. Leaf proline and abscisic acid(ABA) contents increased after water stress. However, changes in proline and ABA contents were not consistently related to the changes in LA as affected by water stress. As the soil water potential decreased, the yield reduction of Hodgson 78 showing large decrease in LA and TDW in response to water deficit was severe when compared to that of Baegunkong with small decrease in LA and TDW. Relatively greater yield stability and higher average yield across soil water potential were observed in Baegunkong. Of specific interest was the small reduction in yield of Paldalkong in spite of its significant decrease in LA and TDW.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.61-70
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• 2018

This study examined how to determine the optimal sediment level in dam reservoir for efficient plan and operation of dam. Currently, Korea is applying a horizontally accumulated method for sediment level estimation for the safety design of dam and so the method estimated relatively higher level than others. However, the sediment level of dam reservoir should be accurately estimated because it is an important factor in assessing life cycle of a dam. The sediment level in dam reservoir can be determined by SED-2D model linked with RMA-2, horizontally accumulated method, area increment method, and empirical area reduction method. The estimated sediment level from each method was compared with the observed sediment level measured in 2007 in Imha dam reservoir, Korea and then the optimal method was determined. Also, the future sediment level was predicted by each method for the future trend analysis of sediment level. As the results, the most accurate sediment level was estimated by the empirical area reduction method and the future trend of sediment level variation followed the past trend. Therefore, we have found that the empirical area reduction method is a proper one for more accurate estimation of sediment level and it can be validated by the results from a numerical model of SED-2D linked with RMA-2 model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.67-74
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• 2021

This paper evaluated the structural safety of an aging PSC I-girder bridge with rebar corrosion in the deck. The geometry and rebar of the bridge were designed based on an actual PSC I-girder bridge, and the numerical analysis was performed considering the crack of concrete and yielding of steel rebar. According to the evaluation criteria of Korea Infrastructure Safety and Technology Corporation, this study defined two criteria of rebar exposure and corrosion rates to construct a total of 32 corrosion scenarios. Rebar exposure was defined as the exposure of tensile rebars in the bridge deck due to the removal of cover concrete. The results of the analysis showed that the safety and rating factors of the bridge decreased with increasing rebar exposure and corrosion rates. For the rebar corrosion rate more than 50%, the safety grade of the bridge should be carefully evaluated for all the rebar exposure rate. When the rebar corrosion rate exceeds 57%, the bridge was evaluated as E grade regardless of rebar exposure rate. A correlation analysis for a 2% of rebar exposure rate found that the bridge was evaluated as A grade up to 55.8% corrosion rate, C grade up to 56.9%, D grade up to 58.5%, and E grade for corrosion rate greater than 58.5%. This study indicates the necessity of a quantitative evaluation of rebar corrosion for evaluating the structural safety of aging bridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.535-546
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• 2008

Urbanization results in increased runoff volume and flowrate and shortening in time of concentration, which may cause frequent flooding downstream. The retardation structures are used to eliminate adverse downstream effects of urban stormwater runoff. There are various types of flow retardation measures include detention basin, retention basin, and infiltration basin. In this study, to present a rough standard about location of detention pond for attenuating peak flow of urban area, the runoff reduction effect is analyzed at outlet point when detention pond is located to upstream drainage than outlet. The runoff reduction effects are analyzed under the three assumed basins. These basins have longitudinal shape (SF = 0. 204), concentration shape (SF = 0. 782), and middle shape (SF = 0.567). Numerous variables in connection with the storage effect of detention pond and the runoff reduction effects are analyzed by changing the location of detention pond. To analyze runoff reduction effect by location of single detention pond, Dimensionless Upstream Area Ratio (DUAR) is changed to 20%, 40%, 60%, and 80% according to the basin shape. In case of multiple detention pond, DUAR is changed to 60%, 80%, 100%, 120%, and 140% only under the middle shape basin (SF = 0.567). Related figures and regression equations to determine the location of detention pond are obtained from above analysis of two cases in this study. These results can be used to determine the location of appropriate detention pond corresponding to the any runoff reduction such as storage ratio and peak flow ratio in urban watershed.