• Nuclear Engineering and Technology
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• v.7 no.4
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• pp.285-293
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• 1975

A result of the study to determine the depth-dose distribution along the central axis of a polyethylene sphere in diameter of 30cm is described. Depth-dose distribution in the polyethylene sphere for broad beam of monoenergetic photons has been experimentally determined with thermoluminescent dosimeter as a cavity dosimeter. The conversion of dose absorbed in the LiF TLD to dose in the surrounding medium was carried out on the basis of Burlin's generalized cavity theory. Presented in graphical forms are the results obtained. The maximum absorbed doses in the sphere were observed at the depth of about 0.3cm and 0.5cm from the surface of the sphere for the gamma-rays of $^{137}$ Cs and $^{60}$ Co, respectively.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.190-198
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• 2009

This study shows the developing process of the risk assessment models for railway casualty accidents. To evaluate the risks of these accidents, the hazardous events and the hazardous factors were identified by the review of the accident history and engineering interpretation of the accident behavior. The frequency of each hazardous event was evaluated from the historical accident data and structured expert judgments by using the Fault Tree Analysis (FTA) technique. In addition, to assess the severity of each hazardous event, the ETA (Event Tree Analysis) technique and other safety techniques were applied. The risk assessment models developed can be effectively utilized in defining the risk reduction measures in connection with the option analysis.

• Explosives and Blasting
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• v.9 no.1
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• pp.3-13
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• 1991

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill ${\phi}70mm$ on the calcalious sand stone (soft -modelate -semi hard Rock). The total numbers of test blast were 88. Scale distance were induced 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ were V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum charge per delay-period of eight milliseconds or more (kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents where the quantity $\frac{D}{W^b}$ is known as the scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagorized in three groups. Cubic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge Per delay Plots of peak particle velocity versus distoance were made on log-log coordinates. The data are grouped by test and P.P.V. The linear grouping of the data permits their representation by an equation of the form ; $V=K(\frac{D}{W^{\frac{1}{3}})^{-n}$ The value of K(41 or 124) and n(1.41 or 1.66) were determined for each set of data by the method of least squores. Statistical tests showed that a common slope, n, could be used for all data of a given components. Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m ------- under l00m ${\cdots\cdots\cdots}{\;}41(D/sqrt[2]{W})^{-1.41}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}A$ Over 100m ${\cdots\cdots\cdots\cdots\cdots}{\;}121(D/sqrt[3]{W})^{-1.66}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}B$ where ; V is peak particle velocity In cm / sec D is distance in m and W, maximLlm charge weight per day in kg K value on the above equation has to be more specified for further understaring about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.213-223
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• 2011

The status and changes of water quality of national fishing harbors and designated ports in East Coast of Korea were analyzed to support establishment effective water environmental management. COD (Chemical Oxygen Demand) concentration was satisfied to designated water quality criteria in most areas, but TN (Total Nitrogen) and TP (Total Phosphorus) exceeded the criteria frequently. Also, peak concentration was summer in COD and SS (Suspended Solid), but winter in TP. Eutrophication index of Ganggu and Pohang (old) area were the highest. Pollution index by function of COD, TN, and TP of Ganggu, Pohang, Jumunjin, and Guryongpo was high with gradual increasing recently, on the contrary, that of Samcheok, Imwon, and Chuksan was decreased. Pollution index involving multi-indictors relation to organics and inorganics was necessary for water quality assessment. Designated water quality criteria needed to be improved because the criteria of Jukbyun and Chuksan was applied more strictly compared to the other regions although without difference of environmental characteristics. Furthermore, the criteria notified lately needed to be related to management pollutants from land-based sources. The continuous diagnosis and monitoring on sediment quality within the study area were necessary for prevention of water pollution and eco-friendly disposal of dredged sediment. Especially, monitoring of Designated Ports was implemented partially, however monitoring ratio of National Fishing Har-bors was 7% to whole part. Therefore, systematic and integrated environmental monitoring for ports and harbors with charge of national management was reestablished by strengthening and securing a legal basis.

• Polymer(Korea)
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• v.34 no.5
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• pp.415-423
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• 2010

Poly(vinyl alcohol)(PVA) with high degree of hydrolysis of above 98% was dissolved in dimethyl sulfoxide(DMSO), and the shear viscosity was measured up to $C{\simeq}0.14\;g/mL$ in the semi-dilute solution regime. Next, as probe particle, polystyrene(PS) latex was introduced into this matrix system and its delayed diffusion due to polymer concentration was investigated by means of dynamic light scattering. When the solution viscosity of PVA/DMSO was plotted against the reduced concentration $C[{\eta}]$, which is scaled by the intrinsic viscosity, the molecular weight dependence was strongly appeared at C$[{\eta}]$ >2. Some heterogeneties in polymer solution were considered as its source. Contrary, the diffusion of probe particle in the matrix solution was observed as a single mode motion at whole concentration range but its ratio of its diffusion coefficient at solution to that at solvent, D/Do did not show any molecular weight dependence at all. However, the application limit of the stretched exponential function was disclosed at C$[{\eta}]$ >2.5.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.66-75
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• 2006

This study was conducted to understand the biomass and the energy content of 24-year-old Pinus koraiensis stand planted in Mt. Wolak, Chungcheongbuk-do, Korea. Nine sample trees were selected and harvested for the study. Stem, bark, branches and leaves were weighed respectively with the stratified clipping method, and analyzed for productive structure. The allometric regression equations between dry weight of each component and $D^2H$ were obtained to estimate the total biomass of aboveground (47.0 ton/ha) and other parts (56.5% from stemwood, 9.1% from stembark, 0.5% from current twigs, 18.4% from live branches, 2.6% from current leaves, and 12.9% from previous leaves). Annual net production of aboveground was 6.0 ton/ha/yr, and the ratios of stemwood, stembark, current twigs, live branches, and current leaves to that of aboveground were 49.8%, 7.3%, 3.5%, 18.6%, and 20.8%, respectively. Energy content of aboveground was 1,028 GJ/ha, and annual energy content was 133 GJ/ha/yr. Leaf area index (LAI) of P. koraiensis plantation was 20.2 in Mt. Wolak.

• Water for future
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• v.27 no.4
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• pp.135-143
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• 1994

The purpose of this study was to improve the understanding of the characteristics of the daily urban water use. The city of Kwangju in Korea was selected as a study area. The population of Kwangju in the end of 1993 was more than one million and two hundred thousand peoples. The average of daily water use in 1993 was about three hundred and fifty thousand tons a day. The variation of the urban water demand trend with time for a day was studied. One day was devided into 12 divisions with a 2hour increment. The water use demand for the given time interval of a day was observed. The water use index was defind in percentage that indicates the ratio of the amount of water use for a time interval to the amount of water use for a day. The water use index was found to be useful to manage and to operate the water supply systems. In addition to this, the probability distribution of the water use demand for each time interval was tested using the K-S(Komogorov-Smirnov) method. The normal distribution type was found to be appropriate as the probability distribution type for the variation of water demand for the given time interval of a day.

• Journal of Korea Port Economic Association
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• v.26 no.3
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• pp.75-91
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• 2010

The aim of this study is to analyze current level of knowledge management(KM) performance in major container terminals. To achieve this aim, the evaluation criteria and KM performance index from pervious research were adopted. and current levels of KM performance of four leading container terminal operators which is located in Busan port were measured. The results firstly showed that average of KM level of these terminal operators was 67.7. And also, from the results of data analysis, it revealed that the weak point of KM in Korean leading terminal operators is official system and programs such as incentive policies, learning programs, and IT support systems for organizational knowledge sharing and knowledge codification.

• KDI Journal of Economic Policy
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• v.9 no.2
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• pp.71-88
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• 1987

본고(本稿)에서는 소비지출(消費支出)을 상이(相異)한 가구특성(家口特性)을 지닌 단위가구(單位家口)의 소비지출(消費支出)로 환산(換算)하기 위한 지수(指數)(디플레이터), 즉 상이(相異)한 가구특성(家口特性)들을 지닌 도시가구(都市家口)의 동등화소비단위(同等化消費單位)를 추계(推計) 분석(分析)하였으며 이를 위하여 "조르겐슨-슬레스닉"의 모형(模型)을 적용(適用)하였다. 특징적(特徵的)으로 나타난 결과는 다음과 같다. 첫째, 품목별(品目別) 동등화소비단위(同等化消費單位)나 총화(總和) 동등화소비단위(同等化消費單位) 모두 가구주(家口主) 직종별(職種別)로는 일용근로자(日傭勤勞者), 자영업자(自營業者), 봉급자(俸給者)의 순서로 높아지고 가구원수(家口員數)는 3명(名)에서 4명(名)으로 느는 데 따라 크게 증가되고 있다. 둘째, 가구원수(家口員數)의 증가(增加)에 따른 동등화단위(同等化單位)의 증가와 일관성 있게 가구주(家口主) 연령별(年齡別)로는 자녀(子女)를 한두 명 두게 되는 25~29세(歲)의 연령층(年齡層)에 유의(有意)한 동등화단위(同等化單位)의 증가가 있는 것으로 나타났다. 셋째, 지출항목별(支出項目別)로는 광열비(光熱費)와 수도료(水道料)를 제외한 모든 지출비용(支出費用)에서 소비생활(消費生活)에 있어서 규모(規模)의 경제(經濟)가 나타난 바 이러한 광열비(光熱費)와 수도료(水道料)의 추정결과(推定結果)는 우리나라에 있어서 누진적(累進的)인 요율체계(料率體系)에서 기인(基因)한 것으로 해석된다. 이 연구(硏究)가 함축하는 가장 큰 정책적(政策的) 의미(意味)는 일용근로자가구(日傭勤勞者家口)의 동등화소비단위(同等化消費單位)가 가장 낮음으로써 같은 수준의 경제성장률(經濟成長率)을 전제하더라도 이들에게 소득(所得) 및 소비(消費)의 증대(增大)가 일어나면 국민경제(國民經濟) 전체로서의 복지후생수준(福祉厚生水準)이 가장 크게 향상될 수 있음을 함축하고 있는 데 있다.

• Fire Science and Engineering
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• v.14 no.3
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• pp.27-32
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• 2000

The assessment of wildland fire hazard is the first priority to be considered in the prevention, extinction and control of wildland fire. For the standard to measure wildland fire hazard, the wildland fire Warning System is currently being used in Korea which computes the wildland fire occurrence hazard index through a stick weight to moisture conversion formula. It shows the risk of fuel substance being exposed to fire by meteorological factors. For a comprehensive assessment of wildland fire hazards by area, the major factors'hazards need to be measured and the assessment of wildland fire needs to be conducted through historical statistic examination. Therefore, the wildland (ire outbreak frequency and its seriousness of damage are analyzed through historical statistic examination to conduct the assessment of a wildland fire hazard, and then the calorific value of a forest is analyzed through differential scanning calorimeter measurement which assesses the comparative calorific hazard according to the geographical distribution of vegetation.