• Environmental and Resource Economics Review
• /
• v.17 no.3
• /
• pp.135-166
• /
• 2008

This paper reports the empirical results of comparing the willingness to pay(WTP) for health risk reductions and the willingness to accept(WTA) for risk increases using experimental market methods in the first time in Korea. Health risks were defined as probabilities of premature death from exposure to one of As, Pb, and THM in tap water. A total of six experimental markets with 15 participants in each experiments were held using 20 repetitive Vickrey second-price sealed-bid auctions. To compare the effects of market experiences, trading a marketed good, candy bar, was introduced before the trading the non-marketed good, drinking water risks. Moreover, an objective risk information was provided after the first 10 trials to incorporate learning processes. Regardless of marketed or non-marketed goods, the mean of WTA exceeded the mean of WTP at the first auction trial. As experimental trials proceeded, the disparity between WTA and WTP for marketed goods disappeared. However results for non-marketed goods were rather mixed to the extent that WTA for health risks from As (relatively high risk leves) were significantly larger than WTP, while there were no significant difference between WTA and WTP for health risks fro Pb and THM (relatively low risk levels). On the other hand, participants seemed to respond in a 'rational' manner to the objective risk information provided, with positive learning effects of market-like experience(especially in the WTA experiments).

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.32 no.3
• /
• pp.87-101
• /
• 1990

The purpose of this study is to estimate the flood discharge and runoff volume at a stream by using geomorphologic parameters obtained from the topographic maps following the law of stream classification and ordering by Horton and Strahier. The present model is modified from Cheng' s model which derives the geomorphologic instantaneous unit hydrograph. The present model uses the results of Laplace transformation and convolution intergral of probability density function of the travel time at each state. The stream flow velocity parameters are determined as a function of the rainfall intensity, and the effective rainfall is calculated by the SCS method. The total direct runoff volume until the time to peak is estimated by assuming a triangular hydrograph. The model is used to estimate the time to peak, the flood discharge, and the direct runoff at Andong, Imha. Geomchon, and Sunsan basin in the Nakdong River system. The results of the model application are as follows : 1.For each basin, as the rainfall intensity doubles form 1 mm/h to 2 mm/h with the same rainfall duration of 1 hour, the hydrographs show that the runoff volume doubles while the duration of the base flow and the time to peak are the same. This aggrees with the theory of the unit hydrograph. 2.Comparisions of the model predicted and observed values show that small relative errors of 0.44-7.4% of the flood discharge, and 1 hour difference in time to peak except the Geomchon basin which shows 10.32% and 2 hours respectively. 3.When the rainfall intensity is small, the error of flood discharge estimated by using this model is relatively large. The reason of this might be because of introducing the flood velocity concept in the stream flow velocity. 4.Total direct runoff volume until the time to peak estimated by using this model has small relative error comparing with the observed data. 5.The sensitivity analysis of velocity parameters to flood discharge shows that the flood discharge is sensitive to the velocity coefficient while it is insensitive to the ratio of arrival time of moving portion to that of storage portion of a stream and to the ratio of arrival time of stream to that of overland flow.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.5
• /
• pp.506-513
• /
• 2020

Due to climate change, there is an increasing risk of complex (hybrid) disasters, comprising rising sea-levels, typhoons, and torrential rains. This study focuses on Marine City, Busan, a new residential city built on a former landfill site in Suyeong Bay, which recently suffered massive flood damage following a combination of typhoons, storm surges, and wave overtopping and run-up. Preparations for similar complex disasters in future will depend on risk impact assessment and prioritization to establish appropriate countermeasures. A framework was first developed for this study, followed by the collection of data on flood prediction and socioeconomic risk factors. Five socioeconomic risk factors were identified: (1) population density, (2) basement accommodation, (3) building density and design, (4) design of sidewalks, and (5) design of roads. For each factor, absolute criteria were determined with which to assess their level of risk, while expert surveys were consulted to weight each factor. The results were classified into four levels and the risk level was calculated according to the sea-level rise predictions for the year 2100 and a 100-year return period for storm surge and rainfall: Attention 43 %, Caution 24 %, Alert 21 %, and Danger 11 %. Finally, each level, indicated by a different color, was depicted on a complex disaster risk map.

• Journal of KIISE
• /
• v.41 no.9
• /
• pp.652-665
• /
• 2014

Many important terminologies in biomedical text are expressed as abbreviations or acronyms. We newly suggest a semantic link topic model based on the concepts of topic and dependency link to disambiguate biomedical abbreviations and cluster long form variants of abbreviations which refer to the same senses. This model is a generative model inspired by the latent Dirichlet allocation (LDA) topic model, in which each document is viewed as a mixture of topics, with each topic characterized by a distribution over words. Thus, words of a document are generated from a hidden topic structure of a document and the topic structure is inferred from observable word sequences of document collections. In this study, we allow two distinct word generation to incorporate semantic dependencies between words, particularly between expansions (long forms) of abbreviations and their sentential co-occurring words. Besides topic information, the semantic dependency between words is defined as a link and a new random parameter for the link presence is assigned to each word. As a result, the most probable expansions with respect to abbreviations of a given abstract are decided by word-topic distribution, document-topic distribution, and word-link distribution estimated from document collection though the semantic dependency link topic model. The abstracts retrieved from the MEDLINE Entrez interface by the query relating 22 abbreviations and their 186 expansions were used as a data set. The link topic model correctly predicted expansions of abbreviations with the accuracy of 98.30%.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.10
• /
• pp.568-574
• /
• 2017

The purpose of this study was to optimize experimental conditions (time ($X_1$) (ranging of 26.36 - 93.64 min), concentration of sulfuric acid ($X_2$) (ranging of 0-2.5%) and temperature ($X_3$) (ranging of $136.4-203.6^{\circ}C$) for an organosolv pretreatment process to extract lignin from waste wood. The resulting quadratic model equation using RSM (response surface methodology) represented y (lignin yield) = $-79.89+0.91X_1+9.8X_2-2.54{\times}10^{-3}X_1{^2}-2.11X_2{^2}$. The $R^2$ (coefficient of determination) value of 0.8531 for a model indicates this model has statistically significant predictors at the 10% levels. The predictive results optimized by quadratic model produced a lignin yield of 12.46 g/100 g of dry wood under conditions of $178.2^{\circ}C$ and 2.32% $H_2SO_4$. The lignin yield was more affected by the acid catalyst concentrations than the reaction temperature, but the reaction time was not an influential factor for improving lignin extraction from waste wood in this organosolv pretreatment. According to ANOVA (analysis of variance), the significance probability (p-value) of model was smaller than 0.001 and simulation of obtained model equations showed a good reproducibility based on actual organosolv tests under optimal conditions.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
• /
• 2003.04a
• /
• pp.123-123
• /
• 2003

야채 soup mix의 제조조건이 야채죽의 물리적 및 관능적 특성에 대한 영향을 조사하였다. Soup mix의 제조조건인 주입액의 양 (쌀 무게에 대한 물의 체적 비), 버섯, 당근 그리고 대파의 첨가량(쌀 무게에 대한 잣의 무게 비)에 따른 물리적 특성과 관능적 특성의 변화를 모니터링 하고자 반응 표면분석법 (response surface methodology, RSM)을 사용하였으며, 이때 실험계획은 중심합성계획법을 적용하였다. 요인변수(Xn)를 중심합성계획에 따라 17실험구로 구분하여 조리실험을 실시하였고, 이들 요인변수에 의해 영향을 받는 반응변수(Yn)는 야채죽의 물리적 특성으로 하여 회귀분석에 사용하였다. 회귀분석에 의한 모델식의 예측에는 SAS (statistical analysis system) program을 사용하였으며, 야채죽의 조리조건이 물리적 및 관능적 특성에 미치는 영향은 SAS program을 이용한 3차원 반응표면분석법으로 해석하였다. 야채의 배합비를 달리한 야채죽의 물리적 특성인 색도 L, a 및 b값에 대한 F-value는 자각 1.50, 11.75 및 5.58이고,유의수준이 각각 0.3044, 0.0019와 0.0169로서 a값과 b값의 유의성이 1% 수준에서 인정되어 이들 제조조건이 a값과 b값에 큰 영향을 미치는 것으로 나타났다. 점도와 퍼짐성에 대한 유의수준은 각각 0.6920과 0.7528이고, 반응표면회귀식의 $R^2$은 각각 0.4766과 0.4436으로 유의성이 인정되지 않았다. 고형분에 대한 유의수준은 0.2026이고 회귀식의 $R^2$는 0.7107으로서 버섯, 당근 및 대파 첨가량이 고형분의 변화에 영향을 미치지 않은 것을 알 수 있었다. 관능적 특성인 색상에 대하여 soup mix의 제조조건이 야채죽에 미치는 영향은 F-value는 6.23이고, 유의수준이 0.0124으로서 1%수준에서 유의성이 인정되었으며, 회귀식의 $R^2$은 0.8890이다. 향에 대한 유의확률은 0.4555이고 0.05이상이므로 유의성이 인정되지 않아 설정된 범위내에서 야채죽의 향에 대하여 크게 영향을 미치지 않는 것으로 나타났다. 점성에 대한 반응표면회귀식의 $R^2$은 0.8134로서 그 유의성이 5%수준에서 인정되었다. 맛과 전반적 기호도에 대하여 야채의 배합비에 따른 반응표면회귀식의 $R^2$은 각각 0.7374와 0.8651이며, 유의화률은 0.1578과 0.0228으로 나타나 전반적인 기호도에 대한 영향은 10% 유의수준에서 영향을 주었다. 결론적으로, 물리적 특성인 색도, 점성, 퍼짐성과 고형분의 함량은 관능적 특성인 색과 비교적 높은 정(正)의 상관을 나타내었으며, 관능적 특성인 향과의 상관은 유의성이 인정되지 않았다. 야채죽 제조를 위한 soup mix의 제조조건에 있어서 야채의 배합비는 색과 점성에 영향을 미치는 가장 주요한 조건이라고 생각된다.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.5
• /
• pp.44-50
• /
• 2014

Chaos communication system is one of the security algorithms that is applied to improve the security. Chaos signal is non-linear, and it is generated randomly according to the initial conditions. Also, chaos communication system has characteristics such as non-periodic, wide-band, non-predictability of signals and easy implementation. So, security of chaos communication system is superior, and it has low interception probability and good anti-jamming characteristic. However, BER performance is worse than digital communication system, because it has many self interference signal in case of CDSK system. To improve these disadvantages, we analyze the PDF trend which can improve the BER performance in existing study, and we proposed a chaos map. And, proposed chaos map was defined as the 'Boss map'. Generally, BER performance is changed according to initial values, parameters and spreading factors. Therefore, in this paper, we will introduce PDF trends which can improve the BER performance, and will describe about Boss map. Also, characteristics of Boss map is analyzed by evaluating the BER performance of Boss map according to initial values, parameters and spreading factors. As a result, while maintaining the similar BER performance, initial value of Boss map can be selected from 0 to 1.2, and BER performance is best when parameter alpha is 2.5. Also, BER performance is best when spreading factor is 50.

• Korea Journal of Hospital Management
• /
• v.23 no.3
• /
• pp.28-38
• /
• 2018

Purpose: To evaluate the medical expenditures for prostate cancer patients, including out-of-pocket costs, and compared the costs between androgen deprivation therapy and radical prostatectomy treatment. Methodology: This study combined clinical data from 357 prostate cancer patients from the Smart Prostate Cancer Database and the medical expenditure data from the claims and cost databases. We used the independent two-sample t-tests to compare androgen deprivation therapy and radical prostatectomy. Multivariable logistic regression analysis was conducted to identify determining factors for androgen deprivation therapy and radical prostatectomy treatments. Findings: The medical costs of androgen deprivation therapy treatment were much lower than radical prostatectomy treatment at the one year and remained lower until the fourth-year. However, after four years, the accumulated medical expenditures of androgen deprivation therapy become significantly higher than radical prostatectomy treatment. Patients with a higher cancer stage and older age had higher chances of being treated using androgen deprivation therapy treatment than radical prostatectomy treatment. Practical Implications: Our results show that early detection of cancer reduces the treatment cost for both patients and insurance payers. It also demonstrates that cost comparisons should be conducted over long periods of time in order to most accurately assess the costs.

• Journal of IKEEE
• /
• v.1 no.1 s.1
• /
• pp.31-46
• /
• 1997

In this paper, a parallel Optimal Best-First search Branch-and-Bound(B&B) algorithm(pobs) is designed and evaluated for MIN-based multiprocessor systems. The proposed algorithm decomposes a problem into G subproblems, where each subproblem is processed on a group of P processors. Each processor group uses tile sub-Global Best-First search technique to find a local solution. The local solutions are broadcasted through the network to compute the global solution. This broadcast provides not only the comparison of G local solutions but also the load balancing among the processor groups. A performance analysis is then conducted to estimate the speed-up of the proposed parallel B&B algorithm. The analytical model is developed based on the probabilistic properties of the B&B algorithm. It considers both the computation time and communication overheads to evaluate the realistic performance of the algorithm under the parallel processing environment. In order to validate the proposed evaluation model, the simulation of the parallel B&B algorithm on a MIN-based system is carried out at the same time. The results from both analysis and simulation match closely. It is also shown that the proposed Optimal Best-First search B&B algorithm performs better than other reported schemes with its various advantageous features such as: less subproblem evaluations, prefer load balancing, and limited scope of remote communication.

• Journal of Radiation Protection and Research
• /
• v.38 no.2
• /
• pp.60-67
• /
• 2013

A diffusion coefficient is an important parameter in the prediction of atmospheric dispersion using a Gaussian plume model, and its modelling approach varies. In this study, dispersion coefficients recommended by the U. S. Nuclear Regulatory Commission's (U. S. NRC's) regulatory guide and the Canadian Nuclear Safety Commission's (CNSC's) regulatory guide, and used in probabilistic accident consequence analysis codes MACCS and MACCS2 have been investigated. Based on the atmospheric dispersion model for a hypothetical accidental release recommended by the U. S. NRC, its influence to atmospheric dispersion factor was discussed. It was found that diffusion coefficients are basically predicted from a Pasquill- Gifford curve, but various curve fitting equations are recommended or used. A lateral dispersion coefficient is corrected with consideration for the additional spread due to plume meandering in all models, however its modelling approach showed a distinctive difference. Moreover, a vertical dispersion coefficient is corrected with consideration for the additional plume spread due to surface roughness in all models, except for the U. S. NRC's recommendation. For a specified surface roughness, the atmospheric dispersion factors showed differences up to approximately 4 times depending on the modelling approach of a dispersion coefficient. For the same model, the atmospheric dispersion factors showed differences by 2 to 3 times depending on surface roughness.