• The Korean Journal of Applied Statistics
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• v.32 no.2
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• pp.187-198
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• 2019

Extensive literature exists on how to estimate optimal thresholds based on various accuracy measures using receiver operating characteristic (ROC) and cumulative accuracy profile (CAP) curves. This paper now proposes an alternative measure to represented the specific partial area under the ROC and CAP curves. The relationship between ROC and CAP functions is examined using differential equations of the new defined partial area under curves. In addition, the relationship with the optimal thresholds under conditions of various accuracy measures for the ROC and CAP functions is also derived. We assume there are two kinds of distribution functions composing the mixed distribution as various normal distributions before finding the optimal thresholds. Corresponding type 1 and 2 errors are also explored and discussed under various conditions for accuracy measures.

• Water for future
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• v.12 no.1
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• pp.56-59
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• 1979

A prompt subsurface runoff producing mechanism whih creaters a depletion curve of direct runoff hydrograph is simulated by a dead zone dispersion model technique. Runoff processes are carried out by routing of the outflow resulted from previous linear channel and effective rainfall from its corresponding subwatershed through a series of conceptual linear channels representing subwatersheds of a catchment. Working rules are explained for evaluation the model parameters such as translatory velocity, diffusive factor, and parameters concerning the infiltration and relative magnitude of the prompt subsurface flow region.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.460-464
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• 2007

개구리밥, 생이가래, 은행이끼, 수련, 부들 등 5종의 식물을 대상으로 카드뮴 $(Cd^{2+})$의 농도를 달리하여 처리한 후 시간별로 식물의 광합성효율을 분석하였다. 그 결과, 개구리밥, 생이가래, 은행이끼, 부들 등 4종은 카드뮴에 민감한 것으로 조사되었고, 수련은 다른 식물종에 비해 덜 민감한 것으로 나타났다. O-J-I-P 곡선의 패턴을 살펴보면, 종에 따라 다소의 차이는 있으나 개구리밥, 생이가래, 은행이끼, 부들 등 4종의 식물은 카드뮴 농도가 증가할 수록 J, I, P값이 크게 감소하는 것을 볼 수 있었다. 특히 P-단계의 감소는 개구리밥에서 현저하게 나타나 다른 3종 보다 카드뮴에 민감한 것으로 보인다. 광계II의 광합성효율(Fv/Fm) 변화양상을 보면, 개구리밥과 생이가래는 카드뮴 농도가 50uM 이상에서는 배양 1일부터 Fv/Fm값이 급격하게 감소하였으며, 은행이끼와 부들은 3일 이후부터 50uM 이상의 카드뮴 농도하에서 Fv/Fm값이 감소하였다. 수련은 큰 변화를 보이지 않았다.

• Ecology and Resilient Infrastructure
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• v.6 no.1
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• pp.1-11
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• 2019

This study performed the impact of ecological waterway on fish community in a reach of the Dal River, Korea. Fish monitoring revealed that 9 fish species are dominant, namely Zacco platypus, Coreoleuciscus splendidus, Zacco koreanus, Pungtungia herzi, Acheilognathus yamatsutae, Rhinogobius brunneus, Tanakia signifer, Gobiobotia macrocephala, and Pseudopungtungia tenuicorpus, and account for 95% of the total fish community. The River2D model was used for the computation of the flow and the HSI model for the habitat simulation. The restoration of the waterway performed through the small dam removal, the formation of the pool-riffle structure, and the change of the bed elevation and width. Simulation results indicated that the restoration of the ecological waterway effects significantly increased by about 16% for the WUA (Weighted Usable Area) of the total fish community in optimal ecological flow conditions ($Q=7.0m^3/s$). The restoration of the ecological waterway is more advantageous to fish community.

• Korean Journal of Plant Resources
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• v.30 no.5
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• pp.481-488
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• 2017

Under circumstances of rapid disappearing of traditional ethnobotanical knowledge, traditional ethnobotanical knowledge surveys are the major step in documenting useful species with a conservation priority. In the ethnobotanical research, the relevance to the survey intensity, ethnobotanical information and plant species richness is the most important research theme. We made up TEK database in south Korea using metadata which had been published by the Korea National Arboretum. We calculated species richness using species richness estimator like ACE, Chao1, Chao2, ICE, Jack 1, Jack 2, and Bootstrap. Species accumulation curves showed each province sampling efforts appeared to be wide range of variance so that Gangwon province need more sampling efforts, and Chungnam province approached a horizontal asymptote earlier. We found heterogeneous patterns in the rarefaction curves of TEK species between gender for each categories of use (medicinal, food and handicrafts). Comparing with regional floral diversities, it was predicted that more diverse species would be found in some provinces by carrying out additional survey.

• Fire Science and Engineering
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• v.33 no.2
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• pp.47-55
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• 2019

The prediction performance of design fire curves was evaluated using a Fire dynamics simulator (FDS) for a solid fuel fire in a building space by comparing the results with experimental data. EDC 2-step mixing controlled combustion model was used in the FDS simulations and the previously suggested 2-stage design fire (TDF), Quadratic and Exponential design fire curves were used as the FDS inputs. The simulation results showed that smoke propagation in the building space was significantly affected by the design fire curves. The predictions of simulations using design fire curves for the experimental temperatures in the building space were reasonable, but the TDF was found to be the most acceptable for predicting temperature. The predictions with each design fire curve of species concentrations showed insufficient agreement with the experiments. This suggests that the combustion model used in this study was not optimized for the simulation of a solid fuel fire, and additional studies will be needed to examine the combustion model on the FDS prediction of solid fires.

• Korean Journal of Poultry Science
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• v.49 no.4
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• pp.229-237
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• 2022

This study investigated the growth characteristics of four strains of newly developed synthetic Korean native commercial chickens (KNCs). We investigated a suitable growth curve model in KNCs and estimated the number of days to reach a 2 kg market weight. Body weight was measured at 2-week intervals from birth to 12 weeks of age. The growth curves were estimated using von Berteralanffy, Gompertz, and logistic functions. The results showed that males were significantly heavier than females at all ages, but there were no significant differences in body weight between strains, except at birth and 2 and 6 weeks of age. The coefficients of determination and adjusted determination of growth function had high goodness-of-fit (97.4~99.7). Of the growth curve parameters, the mature weight and growth ratio were higher in males than in females, but the maturity rate was similar in males and females. The inflection point occurred at approximately 7 weeks of age for females and 8 to 9 weeks of age for males. The weights estimated from the growth curve functions almost agreed with the actual weights, except for male weights estimated using the von Bertalanffy function. The coefficients of determination of the regression equations for weight to age were 0.9583 to 0.9746. The 8- and 10-week-old body weights estimated using the regression equation, and the 12-week-old weight estimated using the logistic function were most similar to the actual weight. Using these models, the estimated age of KNCs to reach 2 kg was 62.0~64.6 days for males and 74.9~78.6 days for females.

• Journal of the Korean Society for Railway
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• v.4 no.2
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• pp.19-28
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• 2001

고속철도에서는 고속주행으로 인한 탈선을 방지하기 위하여 연직 또는 평면선형에 대하여 매우 엄격히 제한하고 있다. 종방향 경사는 2.5% 이하, 평면곡선반경에 대하여는 7,000 m 이상으로 규정하고 있으므로, 도로는 물론 일반철도에 비하여 교량구조물 발생은 더욱 증가된다. 한편 고속철도 교량은 구조물의 안전성 뿐만 마니라 승차감을 위하여 동적거동에 대하여 엄격히 제한된다. 또한 교량과 레일의 상호작용 등에 따라 무한장 개념의 레일에 악영향을 피하기 위해 교량의 종방향 변위도 제한되기 때문에 지간 장이 짧고 상판 구조물은 큰 강성을 갖게 된다. (중략)

• Journal of Korea Water Resources Association
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• v.39 no.12 s.173
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• pp.1023-1030
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• 2006

The characteristics of the longitudinal velocity in a $180^{\circ}$ constant-radius, recirculating laboratory channel were investigated. Three-dimensional velocity fields were measured using a side-looking ADV. The shortcomings of existing equations for longitudinal velocity are discussed. An eddy viscosity model is adopted in the downstream momentum equation. A mathematical equation was developed to describe the vertical distribution of longitudinal velocity. The comparisons of the longitudinal velocity show generally good agreement. It is found that the curvature change in the curved channel affects the vertical location of maximum velocity and the vertical profile of longitudinal velocity.

• Analytical Science and Technology
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• v.27 no.4
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• pp.201-212
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• 2014

Polycyclic aromatic hydrocarbons (PAHs) that are carcinogenic and persistent will be restricted in consumer products from December 27, 2015 by EU REACH regulation. Pretreatment using Soxhlet extraction and quantitative analysis by GC-MS were studied to develop the method for analyzing 18 PAHs in consumer products as well as to detect the amounts and the kinds of PAHs in consumer products such as grips of a bag and a hammer, a cable and a plastic sandal. Linearity and precisions were evaluated by analyses of the standard PAH solutions ranging from 0.3125 mg/L to 5.00 mg of each of 18 PAHs. Linearity of resulting standard curves for all 18 PAHs were obtained with $R^2$ above 0.999. Precisions of the retention times and the peak areas were found to be 0.00%~0.05% and 1.16%~3.69% of relative standard deviations, respectively. The recoveries for spiked samples were all around 95%~105% after Soxhlet extration using three different solvents such as dichloromethane, hexane and toluene. The limits of quantitation for 18 PAHs in solutions and polymer samples by GC-MS were evaluated to be 0.327 mg/L (Benzo[ghi]perylene)~0.464 mg/L (Acenaphthylene) and 1.635 mg/kg (Benzo[ghi]perylene)~2.32 mg/kg (Acenaphthylene) based upon dilution factor of 5, respectively. Under the developed analytical method, only trace amounts of phenanthrene were detected in three samples while 15 kinds of PAHs including phenanthrene were detected in a grip of hammer with concentrations of maximum 83.4 mg/kg of Phenanthrene and minimum 8.5 mg/kg of Acenaphthylene. Further studies are needed to decrease the quantitation limit and to check the feasibility of decreasing Soxhlet time as well as to demonstrate cases that the clean up is required.