• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.13-23
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• 2000

In this study, an flexural test on half-scale spliced PSC-I girder was conducted to verify the efficiency of the long span spliced girder as suggested by the Korean Highway Design Specification. The experimental results showed that the specimens developed a complex failure mode due to flexural-compression and torsional stress. The cracking moment of each girder was higher the experiment than was calulated by the ACI and the ultimate strength were the almost same. To estimate the safety and the structural efficiency of the spliced girder, the proposed Yielding Resistance Index(YRI) and ductility index by American Concrete Institutes were used based on the energy concept. The proposed YRI defined the ratio of crack resisting energy and the total energy calculated from load-displacement relationship. Based on the analysis of YRI and ductility index, the flexural behavior of the spliced girder was found to be efficient. Through the experimental results, the structural behavior of proposed spliced PSC I-type girder for long span bridge was found to be more efficient than the exsisting PSC I-type girders.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.93-101
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• 2006

풍력발전의 보급확대는 전력시장의 특성으로 인하여 국가적 차원의 정책에 의존될 수 밖에 없는 태생적 한계를 지니고 있다. 역설적으로, 풍력발전은 정부기획에 의하여 시장조성(설계)이 가능하고, 따라서 풍력발전과 관련한 설비제조업, 발전사업, 단지 건설업 및 서비스업 등으로 구성되는 '풍력산업'은 국가적 차원의 적정한 정책 수단으로 육성될 수 있는 새롭게 부상하는 산업부문이다. 선진 외국의 전력시장에서 관찰되는 풍력산업의 출현 및 성숙과정을 참고로, 우리나라에서의 풍력발전의 보급확대를 위한 전략을 원론적 차원에서 모색하고자 하였다. 기술경영학적 관점에서 풍력산업의 육성도 결국 '기술주도'가 아닌 '시장주도'에 의한 것이 효과적일 수밖에 없으며, 풍력발전의 보급확대를 통한 수요의 창출은 에너지믹스(Energy Mix)와 관련한 국가차원의 정책적 의지와 선택의 문제일 뿐이다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.375-378
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• 2008

This paper aims at identifying the factors that have influenced changes in the level of industrial $CO_2$ emissions. By means of complete decomposition method the observed changes are analyzed into five different factors: output level, energy intensity, energy mix and structural change and utility use. The application study refers to the manufacturing sectors in Korea. Moreover, this paper discusses the relationship between Korea's manufacturing $CO_2$ emission and economic growth (as measured by GDP), investigating whether economic growth is decoupling from $CO_2$ emission.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.51-58
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• 2008

Development of a new design guide which is based on empirical-mechanistic concept for pavement design is in action. It is called AASHTO 2002 Design Guide in USA and the KPRP(Korean Pavement Research Project) in Korea. The material characteristic of hot mix asphalt is a key role in the design guide. Therefore it is urgent to get a proper materials database, especially the dynamic modulus of hot mix asphalt. In this research, dynamic modulus test, which is based on aged asphalt binder, has been carried out and proposed the predicted equation of dynamic modulus. Nine different hot mix asphalt with three different asphalt binder have been used for the dynamic modulus test. Short-term aging, which is covers the time for the production of asphalt plant, transportation, lay-down, and compaction, can be simulated at $135^{\circ}C$ with 2 hour curing. Long-term aging has been carried out for a performance period of asphalt pavement. The dynamic modulus of asphalt pavement increases with aging time. As the nominal aggregate size increases, the change of dynamic modulus is not big.

• Korean Management Science Review
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• v.30 no.1
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• pp.139-148
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• 2013

A nuclear energy has been one of the most important sources to securely supply electricity in South Korea. Its weight in the national electricity supply has kept increasing since the first nuclear reactor was built in 1978. The country relies on the nuclear approximately 31.4% in 2012 and it is expected to increase to 48.5% in 2024 based on the long-term electricity supply plan announced by the Korean government. However, Fukushima disaster due to 9.0 magnitude earthquake followed by the tsunami has raised deep concerns on the security of the nuclear power plants. The policy makers of the country are much interested in analyzing the cost structure of the power supply in the case that the nuclear is diminished from the current supply portion. This research uses a stochastic model that aims to evaluate the long-term power supply plan and provides an extensive cost analysis on the changes of the nuclear power supply. To evaluate a power supply plan, the research develops a few plausible energy mix scenarios by changing the installed capacities of energy sources from the long-term electricity supply plan. The analyses show that the nuclear is still the most attractive energy source since its fuel cost is very much stable compared to the other sources. Also the results demonstrate that a large amount of financial expenditure is additionally required every year if Koreans agree on the reduction of nuclear to increase national security against a nuclear disaster.

• Journal of the Korean Professional Engineers Association
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• v.45 no.4
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• pp.30-34
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• 2012

Shale gas is one of the resources which require lots of new technologies for commercial production and has the most reserves among unconventional gas resources for commercial production at present. Especially, the growth of shale gas industry means the significant changes of paradigm and the development of shale gas is very different from conventional gas development in terms of geology, rock mechanics, petroleum engineering, development and production engineering. In this manner, shale gas may hold the key to expanding the long-term role of gas in the global energy mix.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.881-883
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• 1987

This paper decribes a new technique for the generation of excitation sources in LPC system. We synthesize a speech signal using several excitation sources, according to residual signal energy and ZCR(zero Crossing Rate). One of the excitation sources mix the double differentiated glottal wave form source and noise source. As a result, we got improved speech signal than that produced by conventional LPC system.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.1
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• pp.97-100
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• 1992

Locally available milk mix, coconut meal, cassava root meal, cassava leaf meal, maize, meat meal, fish meal, rice bran, rice polishings, wallow, molasses and coral sand in Fiji were analysed for proximate components, gross energy and mineral contents. The results obtained indicated typical and variable amounts of nutrients in these materials. On the basis of their nutrient contents, the potential usefulness and weaknesses of the various feed materials are discussed with specific reference to the formulations of diets for livestock and poultry in Fiji based on these locally available feed materials.

• Computers and Concrete
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• v.21 no.3
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• pp.249-259
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• 2018

The use of recycled aggregate in concrete is gaining much attention due to the growing need for sustainability in construction. In the present study, Self Compacting Concrete (SCC) is made using both natural and recycled aggregate (crushed recycled concrete aggregate from building demolished waste) and performance of recycled aggregate based SCC for the bond behaviour of reinforcement is evaluated. The major factors that influence the bond like concrete compressive strength (Mix-A, B and C), diameter of bar ($D_b=10$, 12 and 16 mm) and embedment length of bar ($L_d=2.5Db$, $5D_b$ and full depth of specimen) are the parameters considered in the present study in addition to type of aggregates (natural and recycled aggregates). The mix proportions of Natural Aggregate SCC (NASCC) are arrived based on the specifications of IS 10262. The mix proportions also satisfy the guidelines of EFNARC. In case of Recycled Aggregate SCC (RASCC), both the natural coarse and fine aggregates are replaced 100% by volume with that of recycled aggregates. These mixes are also evaluated for fresh properties as per EFNARC. The hardened properties like compressive strength, split tensile strength and flexural strength are also determined. The pull-out test is conducted as per the specifications of IS 2770 (Part-1) for determining the bond strength of reinforcement. Bond stress versus slip curves were plotted and a typical comparison of RASCC is made with NASCC. The fracture energy i.e., area under the bond stress slip curve is determined. With the use of recycled aggregates, reduction in maximum bond stress is noticed whereas, the normalised maximum bond stress is higher in case of recycled aggregates. Based on the experimental results, regression analysis is conducted and an equation is proposed to predict the maximum bond stress of RASCC. The equation is in good agreement with the experimental results. The available models in the literature are made use to predict the maximum bond stress and compare the present results.

• Atmosphere
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• v.32 no.2
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• pp.119-133
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• 2022

From 2015 to 2021, high-concentration fine dust episodes with a daily average PM_2.5 concentration of 50 ㎍ m^-3 or higher were selected and classified into 3 types [long range transport (LRT), mixed (MIX) and Local emission and stagnant (LES)] using synoptic chart and backward trajectory analysis. And relationships between the fine particle data (PM_2.5 and PM₁₀ concentration and PM_2.5/PM₁₀ ratio) and meteorological data (PBLH, Ta, WS, U-wind, and Rainfall) were analyzed using hourly observation for the classification episodes on the Korean Peninsula and the Seoul metropolitan area (SMA). In LRT, relatively large particles such as dust are usually included, and in LES, fine particle is abundant. In the Korean peninsula, the rainfall was relatively increased centered on the middle and western coasts in MIX and LES. In the SMA, wind speed was rather strong in LRT and weak in LES. In LRT, rainfall was centered in Seoul, and in MIX and LES, rainfall appeared around Seoul. However, when the dust cases were excluded, the difference between the LRT and other types of air quality was decreased, but the meteorological variables (Ta, RH, Pa, PBLH, etc.) were further strengthened. In the case of the Korean Peninsula, it is difficult to find a clear relationship because regional influences (topographical elevation, cities and coasts, etc.) are complexly included in a rather wide area. In the SMA, it is analyzed that the effects of urbanization such as the urban heat island centered on Seoul coincide with the sea and land winds, resulting in a combination of high concentrations and meteorological phenomena.