• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.437-445
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• 2012

The study performed the implementation monitoring of the revegetation methods applied to the test-bed of Simgok Stream in Incheon to identify the effect of water level and inundation period on the vegetation coverage of the stream bank revegetation methods. The categories of monitoring included the plant species and plant coverage for each method, physicochemical property of soil, water level and water quality. The result of monitoring revealed that plant growth conditions of all revegetation methods of each stream bank were good in the first survey as of May 2010. However, in the second survey of June 2011 when inundation period was less than a week, plant growth conditions and coverage of revegetation methods were partially bad. In the third survey as of August 2011 when inundation period was longest as 8 weeks during survey period, most vegetations did not survive except for Phragmites communis. But plant species number and plant coverage were increased gradually in the forth survey as of October 2011 when inundation period was less than 2 weeks so water level decreased more than that of third survey. Accordingly, the correlation analysis among number of plant species and plant coverage on stream bank, which applied revegetation method, water level and inundation period was performed for quantitative analysis. The result revealed that number of plant species and plant coverage has a negative correlation with water level and inundation period, but inundation period had higher correlation with plant occurrence than water level.

• Journal of Environmental Science International
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• v.24 no.7
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• pp.851-864
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• 2015

This study analyzed the climate regime shift using statistical change-point analysis on the time-series tropical cyclone (TC) frequency that affected Japan in July to September. The result showed that there was a significant change in 1995 and since then, it showed a trend of rapidly decreasing frequency. To determine the reason for this, differences between 1995 to 2012 (9512) period and 1978 to 1994 (7894) period were analayzed. First, regarding TC genesis, TCs during the 9512 period showed a characteristic of genesis from the southeast quadrant of the tropical and subtropical western North Pacific and TCs during the 7894 period showed their genesis from the northwest quadrant. Regarding a TC track, TCs in the 7894 period had a strong trend of moving from the far east sea of the Philippines via the East China Sea to the mid-latitude region in East Asia while TCs in the 9512 period showed a trend of moving from the Philippines toward the southern part of China westward. Thus, TC intensity in the 7894 period, which can absorb sufficient energy from the sea as they moved a long distance over the sea, was stronger than that of 9512. Large-scale environments were analyzed to determine the cause of such difference in TC activity occurred between two periods. During the 9512 period, anomalous cold and dry anticyclones were developed strongly in the East Asia continent. As a result, Korea and Japan were affected by the anomalous northerlies thereby preventing TCs in this period from moving toward the mid-latitude region in East Asia. Instead, anomalous easterlies (anomalous trade wind) were developed in the tropical western Pacific so that a high passage frequency from the Philippine to the south China region along the anomalous steering flows was revealed. The characteristics of the anomalous cold and dry anticyclone developed in the East Asia continent were also confirmed by the analysis of air temperature, relative humidity and sensible heat net flux showing that most regions in East Asia had negative values.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.4
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• pp.200-206
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• 2013

Fourier analysis and a wavelet method were carried out to elucidate the characteristics of tidal residual components in coastal waters. The result of Fourier analysis shows tide-induced and monsoon-induced residuals are conspicuous at the short period and mid period, respectively. The tidal residuals were decomposed by period from 3 hours to 8 months and the characteristics of their components were shown by reconstituting them with short periods less than 24 hours, mid-periods between 1 day and 16 days and long periods longer than 1 month. The tidal residuals in the short period, i.e., tide-induced components, being based on the tidal elevation prediction errors, appear in the West Sea with high tidal ranges and do not have much seasonal fluctuation. Additionally, the period of typhoon induced surge ranges more or less than 12 hours. The mid-period components were clearly generated mainly in the West Sea during the winter and largely affected by monsoon. Accordingly, the pure surge height components were concentrated on the mid-period and had clear features for each coastal waters. The long period components show similar characteristics at all stations and are considered to stem from variations of mean sea levels.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.353-361
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• 2018

The purpose of this study is to analyze how Corporate Real Estate Ratio affects Firm's Value for KOSPI Companies and KOSDAQ Companies. The period of analysis is the period of the Financial Crisis (2007-2008), the period immediately after the Financial Crisis (2009-2011), and the period following the introduction of IFRS (2012-2016). The samples of 2761 KOSPI Companies years and 3719 KOSDAQ Companies years are used in this study. The result of Regression Analysis shows that the higher Corporate Real Estate Ratio is, the more negative Firm's Value is. In the comparison of markets, both KOSPI Companies and KOSDAQ Companies had no statistically significant effects during the Financial Crisis. Although KOSDAQ Companies had a greater negative effect on the Firm's Value than KOSPI Companies right after the Financial Crisis, KOSPI Companies have had a greater negative influence on the Firm's Value than KOSDAQ Companies since the introduction of IFRS. Therefore, each corporation should pay more attention to identifying the appropriate amount of their Corporate Real Estate Ratio and should continue to analyze and make decisions on the most efficient use of real estate which is owned by each company. This study shows speciality in dividing into three period, such as the period of the Financial Crisis, the period immediately after the Financial Crisis, and the period following the introduction of IFRS and comparing the degree of influence on the KOSPI Companies and KOSDAQ Companies for the each period. I hope to study the factors that affect the company's real estate policy.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.165-171
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• 2013

The fact that tidal residuals are detected greatly at the tide-dominated region implies that tide component has still remained in the tidal residual. Auto-correlation function analysis also show that the auto-correlation coefficients are conspicuous near tidal periods at the Western Coast. A wavelet method was used to analyze characteristics of the short period or tide-relevant residuals. Considering the results that tidal period is prominent at the tide-dominated region, that seasonal variation is trivial at the short periods, and that shallow tidal period is conspicuous at Mokpo, the short period can be considered to be correlated with tide modulated surge. The result also shows short period components stem mainly from tide-forecasting error and tide-surge interaction. Thus tide modulated surge must be distinguished from meteorological surge.

• Journal of the Korea Society for Simulation
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• v.27 no.3
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• pp.45-52
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• 2018

We consider the busy period of an M/G/1/K queueing system with queue-length-dependent overload control policy. A variant of an oscillating control strategy that was recently analyzed by Choi and Kim (2016) is considered: two threshold values, $L_1({\leq_-}L_2)$ and $L_2({\leq_-}K)$, are assumed, and service rate and arrival rate are adjusted depending on the queue length to alleviate congestion. We investigate the busy period of an M/G/1/K queue with two overload control policies, and present the formulae to obtain the expected length of a busy period for each control policy. Based on the numerical examples, we conclude that the variability and expected value of the service time distribution have the most influence on the length of a busy period.

• Atmosphere
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• v.32 no.1
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• pp.1-15
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• 2022

Recently, Japan's Meteorological Research Institute presented the d4PDF database (Database for Policy Decision-Making for Future Climate Change, d4PDF) through large-scale climate ensemble simulations to overcome uncertainty arising from variability when the general circulation model represents extreme-scale precipitation. In this study, the change of precipitation characteristics between the historical and future climate conditions in the Yongdam-dam basin was analyzed using the d4PDF data. The result shows that annual mean precipitation and seasonal mean precipitation increased by more than 10% in future climate conditions. This study also performed an analysis on the change of the return period rainfall. The annual maximum daily rainfall was extracted for each climatic condition, and the rainfall with each return period was estimated. In this process, we represent the extreme-scale rainfall corresponding to a very long return period without any statistical model and method as the d4PDF provides rainfall data during 3,000 years for historical climate conditions and during 5,400 years for future climate conditions. The rainfall with a 50-year return period under future climate conditions exceeded the rainfall with a 100-year return period under historical climate conditions. Consequently, in future climate conditions, the magnitude of rainfall increased at the same return period and, the return period decreased at the same magnitude of rainfall. In this study, by using the d4PDF data, it was possible to analyze the change in extreme magnitude of rainfall.

• The Journal of the Korea Contents Association
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• v.20 no.5
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• pp.585-594
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• 2020

After the launch of Jeju Special Self-Governing Province in 2006, a number of real estate development projects were carried out; the real estate industry has relatively largely grown as compared with other regions since 2011. This growth has slowed down in 2017, along with the increase of unsold houses and the short of its incoming population, causing its real estate market recession. This study analyzed the source of real estate industry growth in Jeju: either affected by national growth power or its regional competitiveness. This study applied Shift-Share Analysis and Growth Differential Analysis, by dividing the recovery period ('06~'10) and expansion period ('11~'16). According to the result, sales amount and the number of employees in the real estate industry in Jeju had grown in the recovery period based on the national growth power. Its regional competitiveness and stable industrial structure grew in the growth period. Development and subdividing of real estate contributed to the growth of the real estate industry in Jeju. On the other hand, management of real estate weakened its market.

• YAKHAK HOEJI
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• v.53 no.2
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• pp.51-59
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• 2009

Quantitative analysis of (+)-catechin (C), (-)-epigallocatechin (EGC), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and caffeine in commercial green tea was carried out by HPLC employing gradient elution of 0.1% acetic acid and acetonitrile on ODS column. The optimized HPLC method provided satisfactory linearity, accuracy and precision. The relationship between the concentration of the components and cultivated region of the commercial green tea was not significant, while the concentration of EGCG, ECG and caffeine decreased significantly in the later harvested green tea samples (p<0.01). Multivariate analysis of the components was performed in order to characterize and evaluate the cultivated region and harvest period-related variation. Hierarchical clustering and discriminant analysis were applied to classify the geographical and seasonal origins of the green tea samples. The classification accuracy of the cultivated region and harvest period by discriminant analysis was 95% and 91%, respectively, indicating that this method could be reliable and convenient for the quality control of herbal products with different origin.

• Journal of Korean society of Dental Hygiene
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• v.12 no.1
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• pp.37-46
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• 2012

Objectives : This research was investigated to evaluate the psychological characteristics and changes of psychological state among dental orthodontic patients. Methods : This cross-sectional questionnaire research was conducted with 230 dental orthodontic patients in Busan from December 23, 2009 to March 6, 2010. The psychological analysis of dental orthodontic treatment patients was performed with Symptom checklist-90-revision(SCL-90-R) considering 5 general characteristics and 2 treatment period related characteristics. Estimated psychological results were changed T-score. Data analysis was performed with descriptive analysis, t-test and ANOVA using SAS(ver 9.1) program. Results : The levels of T-score of SCL-90-R were $43.88{\pm}7.50$ in hostility(HOS), $43.38{\pm}4.64$ in phobic anxiety(PHOB), $43.20{\pm}6.24$ in somatization(SOM), $42.13{\pm}6.71$ in paranoid ideation(PAR), $41.39{\pm}8.16$ in interpersonal sensitive(I-S), $41.01{\pm}7.90$ in obsessive-compulsive(O-C), $40.96{\pm}5.37$ in psychoticism(PSY), $40.96{\pm}5.19$ in anxiety(ANX) and $39.81{\pm}6.80$ in depression(DEP), respectively. The T-score of phobic anxiety in before treatment group was higher than that of treatment groups. The T-score of interpersonal sensitive and paranoid ideation in over 36 months treatment period group were higher than that of other treatment period groups. Conclusions : Phobic anxiety(PHOB), interpersonal sensitive(I-S) and paranoid ideation(PAR) were affected in pre-treatment and long-term treatment dental orthodontic patients. Psychological management methods considering treatment period are needed to improve mental health of dental orthodontic patients.