• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.101-101
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• 2020

Traditional stochastic simulation of hydroclimatological variables often underestimates the variability and correlation structure of larger timescale due to the difficulty in preserving long-term memory. However, the Long Short-Term Memory (LSTM) model illustrates a remarkable long-term memory from the recursive hidden and cell states. The current study, therefore, employed the LSTM model in stochastic generation of hydrologic and climate variables to examine how much the LSTM model can preserve the long-term memory and overcome the drawbacks of conventional time series models such as autoregressive (AR). A trigonometric function and the Rössler system as well as real case studies for hydrological and climatological variables were tested. Results presented that the LSTM model reproduced the variability and correlation structure of the larger timescale as well as the key statistics of the original time domain better than the AR and other traditional models. The hidden and cell states of the LSTM containing the long-memory and oscillation structure following the observations allows better performance compared to the other tested conventional models. This good representation of the long-term variability can be important in water manager since future water resources planning and management is highly related with this long-term variability.

• Tunnel and Underground Space
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• v.20 no.2
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• pp.119-124
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• 2010

Hopkinson's effect tests were carried out for various strain rates on three different types of rock in both saturated and dry states in order to examine the effects of strain rate and water saturation on tensile strength. The tensile strength increased with the increase of the strain rate not only in dry state but also in saturated state. It was also especially recognizable that the dynamic tensile strength of rock in the dry state was proportional to approximately a one-third multiple of strain rate no matter what the type of rock. It was found that water saturation decreased tensile strength in the dry state of sandstone and tuff, both with high porosity, but no significant difference could be recognized between the dry and the saturated states of granite, which has a low porosity of 0.49%.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.5
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• pp.96-105
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• 2002

As an useful water purification system for non-point source pollution in rural watersheds, interests in constructed wetlands are growing at home and abroad. It is well known that constructed wetlands are easily installed, no special managemental needs, and more flexible at fluctuating influent loads. They have a capacity for purification against nutrient materials such as phosphorus and nitrogen causing eutrophication of lentic water bodies. The Constructed Wetland Design Model (CWDM), developed through this study is consisted mainly of Database System, Runoff-discharge Prediction Submodel, Water Quality Prediction Submodel, and Area Assessment Submodel. The Database System includes data of watershed, discharge, water quality, pollution source, and design factors for the constructed wetland. It supplies data when predicting water quality and calculating the required areas of constructed wetlands. For the assessment of design flow, the GWLF (Generalized Watershed Loading Function) is used, and for water quality prediction in streams estimating influent pollutant load, Water Quality Prediction Submodel, that is a submodel of DSS-WQMRA model developed by previous works is amended. The calculation of the required areas of constructed wetlands is achieved using effluent target concentrations and area calculation equations that developed from the monitoring results in the United States. The CWDM is applied to Bokha watershed to appraise its application by assessing design flow and predicting water quality. Its application is performed through two calculations: one is to achieve each target effluent concentrations of BOD, SS, T-N and T-P, the other is to achieve overall target effluent concentrations. To prove the validity of the model, a comparison of unit removal rates between the calculated one from this study and the monitoring result from existing wetlands in Korea, Japan and United States was made. As a result, the CWDM could be very useful design tool for the constructed wetland in rural watersheds and for the non-point source pollution management.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.495-499
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• 1991

The changes in the free energy and hydration free energy of N-acetyl-N'-methylalaninamide in the unhydrated and hydrated states were calculated with ECEPP/2 and the hydration shell model. The configurational entropy change of each conformation in both states were computed by a harmonic method. To understand the hydration structure of each hydrated conformation, the hydration-shell coordination numbers of functional. groups of the molecule were estimated from water-accessible volumes, and the contributions of water-accessible volume and polarization of each group to the hydration free energy were analyzed. The results show a reasonable agreement with those of recent theoretical studies and experiments.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.3-26
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• 2009

Superloading yield surface concept is newly introduced together with subloading yield surface conception in order to describe full gradation continuously of the mechanical behavior of soils from typical sand through intermediate soil to typical clay (All Soils). Finite deformation theory has been applied to the soil skeleton-pore water coupled continuum mechanics, which enables us to discuss things in a perpetual stream from stable state to unstable state like from deformation to failure and vice versa like from liquefaction to post liquefaction consolidation of sand (All States). Incremental form of the equation of motion has been employed in the continuum mechanics in order to incorporate a rate type constitutive equation, which is "All Round" enough to predict ground behavior under both static and dynamic conditions. The present paper is the shortened version of the lecture note delivered in 2008 Theoretical and Applied Mechanics Conference, Science Council Japan, but with newly developed application examples.

• Journal of Acupuncture Research
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• v.36 no.1
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• pp.21-27
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• 2019

Background: The intelligent tissue hypothesis holds that an organ's states (be it normal function or stressed states) are reflected in real time at its related acupuncture points (acupoints), causing physical, real-time changes in the local tissue. The experiment was devised to test this. Methods: The patient drank chilled water while the impedance at 6 stomach-related acupoints was monitored in real time (sample rate of 1 kHz). Any changes in the local tissue at the acupoints ought to be reflected in changes in the impedance. Results: The impedance at every test acupoint showed a response to the chilled water being ingested. Also, the duodenal pacesetter and the stomach's slow waves were clearly visible in the impedance pattern at all the acupoints. Conclusion: Hence, many separate details of the stomach's function were reflected at these acupoints. The duodenal features were consistent with the traditional indications for these acupoints, which are noted to be able to treat intestinal conditions. Therefore, the results were consistent with the hypothesis and also provided a possible explanation for how the use of these acupoints is able to treat intestinal conditions.

• Korean Security Journal
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• no.36
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• pp.443-467
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• 2013

The purpose of this study is to introduce United States Coast Guard (USCG) in order to suggest a direction to advance the system of Korea Coast Guard. After the effect of United Nations on the Law of the Sea in 1994, the world is facing with new era of maritime age with emergence of new maritime border 'Exclusive Economic Zone(EEZ)'. Along with new maritime era, Korea also has been facing with the conflicts caused from EEZ. Also, there is a increasing concern about maritime safety and security since people looking for maritime tourism and leisure sports are dramatically increasing in Korea. Moreover, national security matters are a big issue in Korea due to the several incidents occurred in the sea such as the attack on Yeon-Pyung Island and the sinking of Cheonan naval vessel. Arising concern on these issues in maritime space requires Korea Coast Guard to handle these effectively. However, the systematical and structural limitation of Korea Coast Guard limits the effective management of recent issues. The United States Coast Guard which is considered as one of the military force in the United States has continuously reformed and developed its system and structure to better handle the maritime safety and security issues through developing project such as the Integrated Deep Water system. Also, maritime police system and structure in the United States is different with in Korea. This study expects to suggest a way to advance the system and structure of Korea Coast Guard through examination of United States Coast Guard and comparing maritime police system and structure between Korea and the United States in order to properly deal with the maritime safety and security issues arising recently.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.2049-2053
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• 2007

KModSim은 수자원배분에 관련된 물리적, 수문학적, 제도적, 그리고 행정적인 요구들을 동시에 만족하도록 디자인된 범용 우선순위 목적 선형최적화 모형으로써 자연유3tt입량과 기득 수리권 혹은 기득 저류권 등과 같은 다양한 형태의 저수권 사이의 조화운영이 가능하다. KModSim은 목적함수에 관련된 제약조건의 유연한 설정과 변경이 가능하며, 기존의 최적화 방법과 다르게 유역통합모의에 관련한 모형변수가 모형내에서 자동적으로 생성되도록 프로그램화 되어있다. 본 연구에서는 금강유역내 수자원의 효율적인 운영을 위하여 과거운영자료를 토대로 저수지운영율을 개발하고 시스템단계(system states)를 이용하여 KModSim 네트워크에 운영율을 적용하였다. 금강유역에서 개발한 운영율을 적용하고 모의한 결과 개발된 운영율은 실제저류량을 잘 재현하는 것으로 나타났다. 본 연구에서 개발된 운영율 및 시스템단계 방법은 다중목적 우선순위 선형최적화 모형을 이용하여 유역의 다양한 수자원운영모의에 사용될 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.225-225
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• 2015

Drought events usually evolve slowly in time and their impacts generally span a long period of time. This indicates that the sequence of drought is not completely random. The Hidden Markov Model (HMM) is a probabilistic model used to represent dependences between invisible hidden states which finally result in observations. Drought characteristics are dependent on the underlying generating mechanism, which can be well modelled by the HMM. This study employed a HMM with Gaussian emissions to fit the Standardized Precipitation Index (SPI) series and make multi-step prediction to check the drought characteristics in the future. To estimate the parameters of the HMM, we employed a Bayesian model computed via Markov Chain Monte Carlo (MCMC). Since the true number of hidden states is unknown, we fit the model with varying number of hidden states and used reversible jump to allow for transdimensional moves between models with different numbers of states. We applied the HMM to several stations SPI data in South Korea. The monthly SPI data from January 1973 to December 2012 was divided into two parts, the first 30-year SPI data (January 1973 to December 2002) was used for model calibration and the last 10-year SPI data (January 2003 to December 2012) for model validation. All the SPI data was preprocessed through the wavelet denoising and applied as the visible output in the HMM. Different lead time (T= 1, 3, 6, 12 months) forecasting performances were compared with conventional forecasting techniques (e.g., ANN and ARMA). Based on statistical evaluation performance, the HMM exhibited significant preferable results compared to conventional models with much larger forecasting skill score (about 0.3-0.6) and lower Root Mean Square Error (RMSE) values (about 0.5-0.9).

• Asian Journal of Innovation and Policy
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• v.11 no.3
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• pp.293-319
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• 2022

By analyzing the adaptive capacity, market formation and policy direction as functional areas of Technological Innovation System (TIS), the article evaluates the progress of renewable energy transition in the Maldives, with the inclusion of ideas from Mauritius and Cabo Verde. On the policy direction in the Maldives, technology roadmaps produced with assistance from International Renewable Energy Agency (IRENA) and Asian Development Bank (ADB) are evaluated. Although there are inducing factors such as the Solar Risk Management Initiative, the progress of energy transition is hindered by the lack of technical capacity and local value chain. The findings indicate the importance of facilitating and establishing industry and knowledge networks, incorporating innovation policies, greater involvement of the local private sector along with international investors, and taking water-energy nexus to achieve complementary targets. The study adds value to knowledge by offering a simplified TIS framework, with a current insight of the energy transition in Small Island Developing States with a focus on the Maldives.