• Journal of Korea Water Resources Association
• /
• v.35 no.4 s.129
• /
• pp.397-410
• /
• 2002

In order to quantitatively identify historical drought conditions and to evaluate their variability, drought indices commonly used. The calculation method for the drought index based on the principal hydrological factors, such as precipitation and reservoir storage, can estimate the duration and intensity of a drought. In this study the Palmer-type formula for drought index is derived for the Nakdong River basin by analyzing the monthly rainfall and meteorological data at 21 stations. The Palmer Drought Severity Index(PDSI) is used for dry land sectors to evaluate the meteorological anomaly in terms of an index which permits time and space comparisons of drought severity. The Surface Water Supply Index(SWSI) is devised for the use in conjunction with the Palmer index to provide an objective indicator of water supply conditions in Nakdong River basin. The SWSI was designed to quantify surface water supply capability of a watershed which depends on river and reservoir water The Standardized Precipitation Index(SPI) is evaluated for various time periods of 1 to 12 months in Nakdong River basin. For the purpose of comparison between drought indices correlation coefficient was calculated between indices and appropriate SPI time period was selected as 10 months for Nakdong River basin. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Nakdong River basin since 1976. It turned out that $'94{\sim}'97$ drought was the worst drought in it's severity. It is found that drought indices are very useful tools in quantitatively evaluating the severity of a drought over a river basin.

• Journal of Korea Water Resources Association
• /
• v.43 no.3
• /
• pp.309-323
• /
• 2010

As climate changes and abnormal climates have drawn research interest recently, many countries utilize the GCM, which is based on SRES suggested by IPCC, to obtain more accurate forecast for future climate changes. Especially, many research attempts have been made to simulate localized geographical characteristics by using RCM with the high resolution data globally. To evaluate the impacts of climate and landuse change on water resources in the Han-river basin, we carried out the procedure consisting of the CA-Markov Chain, the Multi-Regression equation using two independent variables of temperature and rainfall, the downscaling technique based on the RegCM3 RCM, and SLURP. From the CA-Markov Chain, the future landuse change is forecasted and the future NDVI is predicted by the Multi-Regression equation. Also, RegCM3 RCM 50 sets were generated by the downscaling technique based on the RegCM3 RCM provided by KMA. With them, 90 year runoff scenarios whose period is from 2001 to 2090 are simulated for the Han-river basin by SLURP. Finally, the 90-year simulated monthly runoffs are compared with the historical monthly runoffs for each dam in the basin. At Paldang dam, the runoffs in September show higher increase than the ones in August which is due to the change of rainfall pattern in future. Additionally, after exploring the impact of the climate change on the structure of water circulation, we find that water management will become more difficult by the changes in the water circulation factors such as precipitation, evaporation, transpiration, and runoff in the Han-river basin.

• Journal of Korea Water Resources Association
• /
• v.47 no.11
• /
• pp.1039-1050
• /
• 2014

The goal of this study is to demonstrate the diversity of model performance for various climatic elements and indicators. We evaluated the skills of the most advanced 17 General Circulation Models (GCMs) i.e., CMIP5 (Climate Model Inter-comparison project, phase 5) climate models in reproducing retrospective climatology from 1950 to 2000 over the Southeast US for the key climatic elements important in the hydrological and agricultural perspectives (i.e., precipitation, maximum and minimum temperature, and wind speed). The biases of raw CMIP5 GCMs were estimated for 16 different climatic indicators that imply mean climatology, temporal variability, extreme frequency, etc. using a grid-based observational dataset as reference. Based on the error (RMSE) and correlation (R) of GCM outputs, the error-based GCM ranks were assigned on average over the indicators. Overall, the GCMs showed much better accuracy in representing mean climatology of temperature comparing to other elements whereas few GCM showed acceptable skills for precipitation. It was also found that the model skills and ranks would be substantially different by the climatic elements, error statistics applied for evaluation, and indicators as well. This study presents significance of GCM uncertainty and the needs of considering rational strategies for climate model evaluation and selection.

• Journal of Korea Water Resources Association
• /
• v.47 no.1
• /
• pp.25-35
• /
• 2014

The objective of this study is to evaluate TOPLATS land surface model performance through comparison of results of water and energy balance analysis. The study area is selected Nakdong river basin and high resolution hydrometeorological components of which spatio-temporal resolution is 1 hr and 1 km are simulated during 2003 to 2013. The simulated daily and monthly depth of flows are well fitted with the observed one on Andong and Hapcheon dam basin. In results of diurnally analysis of energy components, change pattern throughout the day of net radiation, latent heat, sensible heat, and ground heat under energy balance analysis have higher accuracy than ones under water balance analysis at C3 and C4 sites. Especially, root mean square errors of net radiation and latent heat at C4 site are shown very low as 22.18 $W/m^2$ and 7.27 $W/m^2$, respectively. Mean soil moisture and evapotranspiration in summer and winter are simulated as 36.80%, 33.08% and 222.40 mm, 59.95 mm, respectively. From this result, when we need high resolution hydrometeorological components, energy balance analysis is more reasonable than water balance analysis. And this results will be used for monitor and forecast of weather disaster like flood and draught using spatial hydrometeorological information.

• Journal of the Korea Convergence Society
• /
• v.8 no.9
• /
• pp.301-309
• /
• 2017

This study analyzed the effect of cooperation activities among SMEs. In order to study empirical analysis, we classified the types of cooperation into four dimensions: technology cooperation, human resource cooperation, sales cooperation and financial cooperation. Review the role of the collaborative philosophy as a predictor. This study also analyzed the relationship between cooperation philosophy, cooperation activities and performance. The results of this study are as follows: First, the result of path analysis between cooperation philosophy and cooperation activities shows that cooperation philosophy has an important influence on technical cooperation, human resource cooperation, sales cooperation and financial cooperation. Second, the results of the relationship between cooperation activities and achievements, technical cooperation, human resource cooperation, and sales cooperation have an important influence on cooperation performance. The meaning of this study is as follows. Analyze empirical tests using the PSBP model from a partnership perspective. We are trying to verify the relationship with SMEs. Therefore, we can suggest a beneficial implication to explain the importance of cooperation activities between SMEs. Also, SME business units have a problem with technical information leakage when they form partnerships, but in order to overcome this problem, we can use cooperative philosophies and avoid negative views.

• Korean Journal of Construction Engineering and Management
• /
• v.15 no.4
• /
• pp.39-48
• /
• 2014

The speed of aging society is increasingly getting faster in Korea. Currently, there are over one million elderly living alone, which represents more than 19% of the total elderly in Korea. Although various policies and research have been implemented for caring the elderly living alone, there have been obvious limitations in realization of the caring system due to inconvenience, privacy violation, difficult operation and maintenance. Therefore, the objective of this study is to develop a method and a prototype system to monitor safety of elderly living alone by using energy usage information of automatic meter reading device. The proposed system is expected to improve or resolve the existing limitations and to provide 24 hour monitoring and early detection of death for the elderly living alone without adding staffs for operation and maintenance in a more effective and economic way.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.11A
• /
• pp.1827-1840
• /
• 2001

In digital data transmission/storage systems, the compensation for channel distortion is conducted normally using a training sequence that is known a priori to both the sender and receiver. The use of the training sequences results in inefficient utilization of channel bandwidth. Sometimes, it is also impossible to send training sequences such as in the burst-mode communication. As such, a great deal of attention has been given to the approach requiring no training sequences, which has been called the blind equalization technique. On the other hand, to utilize the limited bandwidth effectively, the concept of partial response (PR) signaling has widely been adopted in both the high-speed transmission and high-density recording/playback systems such as digital microwave, digital subscriber loops, hard disk drives, digital VCRs and digital versatile recordable disks and so on. This paper is concerned with blind adaptive equalization of partial response channels whose transfer function zeros are located on the unit circle, thereby causing some problems in performance. Specifically we study how the problems of blind channel equalization associated with the PR channels can be improved. In doing so, we first discuss the existing methods and then propose new structures for blind PR channel equalization. Our structures have been extensively tested by computer simulation and found out to be encouraging in performance. The results seem very promising as well in terms of the implementation complexity compared to the previous approach reported in literature.

• Journal of the Korean Data and Information Science Society
• /
• v.25 no.6
• /
• pp.1499-1506
• /
• 2014

Random walk is used for describing random phenomenon in various areas but tests for random walk developed so far are known to suffer from size distortion and low power. Kim et al. (2014) proposed a sign test for unit root (${\rho}=1$) hypothesis based on slopes. This article proposes a Wilcoxon signed rank test based on slopes for unit root hypothesis, and compares it with the augmented Dickey-Fuller test and the sign test by a simulation study. Our results confirm that the nonparametric tests are better than ADF test for small samples like n = 30. The results also show that the sign test is better than the Wilcoxon signed rank test and that for 0 < ${\rho}$ < 1 (-1 < ${\rho}$ < 0), the nonparametric tests suffer from power loss (improvement) as normal error changes to double exponential error.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.41 no.4
• /
• pp.42-55
• /
• 2013

The purpose of this study is to figure out the place characteristics of preferable city tourist attractions through the contents analysis of non-academic literatures such as tourist guidebooks and web materials. The most preferable Seoul tourist attractions were selected by their frequency in literatures including Namsan and Hangang as 'natural' places, Dugsu Palace and Gyungbok Palace as 'historical' places, Itaewon and Daehak-ro as 'lively-cultural' places that were classified by their relativistic character. The main findings of the research are as follows. The essential place characteristics of tourist attractions were synthesized in urban, regional and place scale respectively. While 'contrast' was found to be the most distinguished character of the tourist attractions in the urban context, 'connectivity' was found to be the most distinguished character of the tourist attractions in the regional context. In addition, both 'visibility' and 'experience' were found to be the most distinguished characters of the tourist attractions in the place context. The characteristics of these places seem to be the universal fascination factors of city tourist attractions currently recognized by ordinary citizens. We expect to further strengthen the city identity and the city tourism effect by adopting those research results systematically to the urban environment. Therefore, it is needed to vitalize the urban tourist attractions that we make them to be more 'contrasting' with urban areas surrounding them, more 'connective' with vicinity areas and more 'visibly fascinating' and 'experienced actively and meaningfully' in each place of tourist attractions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.1-8
• /
• 2016

In this study, an WiFi fingerprinting method based on the k-nn algorithm was applied to improve the accuracy of location tracking of a moving train on a platform and evaluate the performance to minimize the estimation error of location tracking. The data related to the position of the moving train are monitored by the control center for trains and used widely for the safety and comfort of passengers. The train location tracking methods based on WiFi installed by telecom companies were evaluated. In this study, a simulator was developed to consider the environments of two cases; in already installed WiFi devices and new installed WiFi devices. The developed simulator can simulate the localized estimation of the position under a variety of conditions, such as the number of WiFi devices, the area of platform and entry velocity of train. To apply location tracking algorithms, a k-nn algorithm and fuzzy k-nn algorithm were applied selectively according to the underlying condition and also four distance measurement algorithms were applied to compare the error of location tracking. In conclusion, the best method to estimate train location tracking is a combination of the k-nn algorithm and Minkoski distance measurement at a 0.5m grid unit and 8 WiFi AP installed.