• Journal of Environmental Impact Assessment
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• v.26 no.4
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• pp.217-226
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• 2017

Although the effects of climate change are universal, Small Island Developing States (SIDS) are considered to be most vulnerable. SIDS heavily rely on imported oil and fossil fuels for electricity generation and transportation, which makes them economically vulnerable and exposed to fluctuating oil price. Among the reasons SIDS highly depend on diesel fuel is due to the dispersed population living in remote islands which means, providing electricity through on on-grid system is difficult. Fiji as one of the SIDS, has actively promoted renewable sourced energy through a national plan to mitigate the impacts of climate change. In order to determine how feasible implementing a renewable energy (RE) system will be in Fiji, this study chose a remote island called Mavuva Island to test application of a hybrid RE system using HOMER. A combination of energy storage system (ESS), solar photovoltaic (PV) and diesel generator turns out to be the most cost effective and optimal configuration, resulting in effective greenhouse gas reduction for the given region.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.1-11
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• 2015

WBAN(Wireless Body Area Network) operating around the human body aims at medical and non-medical service at the same time. and it is the short-range communication technology requiring low-power, various data rate and high reliability. Various studies is performing for IEEE 802.15.4, because IEEE 802.15.4 can provide high compatibility for operate WBAN among communication standard satisfiable these requirements. Meanwhile, in the case of coexisting many IEEE 802.15.4-based WBAN, signal interference and collision are the main cause that is decreasing data reliability. but IEEE 802.15.4 Standard does not consider about coexistence of many networks. so it needs improvement. In this paper, To solve about this problem, identify coexistence problem of IEEE 802.15.4-based WBAN by preliminary experiments. and propose a scheme to mitigate the reliability decrease at multiple coexistence WBAN. The proposed scheme can be classified in two steps. The first step is avoidance to collision on the CFP through improving data transmission. The second step is mitigation collision through converting channel access method. Proposed scheme is verified the performance by performing comparison experiment with Standard-based WBAN.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.1
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• pp.5-14
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• 2017

Many web services which use OAuth Protocol offer users to log in using their personal profile information given by resource servers. This method reduces the inconvenience of the users to register for new membership. However, at the time a user finishes using OAuth client web service, even if he logs out of the client web service, the resource server remained in the login state may cause the problem of leaking personal information. In this paper, we propose a solution to mitigate the threat by providing an additional security behavior check: when a user requests to log out of the Web Client service, he or she can make decision whether or not to log out of the resource server via confirmation notification regarding the state of the resource server. By utilizing the proposed method, users who log in through the OAuth Protocol in the public PC environment like department stores, libraries, printing companies, etc. can prevent the leakage of personal information issues that may arise from forgetting to check the other OAuth related services. To verify our study, we implement a Client Web Service that uses OAuth 2.0 protocol and integrate it with our security behavior check. The result shows that with this additional function, users will have a better security when dealing with resource authorization in OAuth 2.0 implementation.

• KDI Journal of Economic Policy
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• v.14 no.1
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• pp.61-87
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• 1992

Reducing the level of greenhouse gas emissions is necessary to mitigate global warming. One of the most feasible methods to reduce emissions would be to conserve energy and substitute fossil fuels. Yet reducing emissions entails huge financial costs, so it is advisable to employ cost-effective economic instruments such as a carbon tax or tradeable emissions permits. Assuming that the proper economic tools will be used in the future, we calculated the optimal level of emissions reduction for Korea. We applied to our cost-benefit analysis Nordhaus' scenario regarding the economic damage from a $3^{\circ}C$ rise in global temperatures, which is the calculated result when the greenhouse gas level doubles. The result of our analysis based on the 1990 data indicates that the optimal level of emissions reduction ranges from 2% to 15 % of current emissions depending on the value of damage parameters. We also found that the amount of emissions must be reduced will increase if action is postponed, when the development of climate engineering technology or more efficient use of energy is expected. In addition, we discussed the advantages and disadvantages of the economic instruments available to implement emissions reduction. Tradeable permits and carbon tax are equivalent in their cost-effectiveness, but have different implications in practice.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.2
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• pp.135-139
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• 2018

This study was conducted to evaluate the forage production and feed value of Sasa borealis (S. borealis) in Jeju Island in order to improve the utilization of Sasa borealis and to help mitigate the problem of reduced plant species diversity caused by S. borealis in Hanlla Mountain. To investigate the forage production, three quadrat structures were installed in the S. borealis natural community in the middle part of Hanlla Mountain. From May to October 2017, S. borealis in quadrats was cut at a fixed time of each month, and then forage production and regenerated acidity per kg/ha were evaluated. For the evaluation of feed value, compositional analysis was performed on the monthly samples. In vitro digestion experiments were carried out using cannula mounted Hanwoo. In vitro neutral detergent fiber digestibility(IVNDFD) and in vitro acid detergent fiber digestibility(IVADFD) were measured after the experiment. Forage production of S. borealis showed relatively good regeneration ability in May and June, but the regeneration ability decreased as the cutting was repeated. In order to use S. borealis as a forage, it is considered efficient to feed black goats with good fiber decomposition or horses good palatability to S. borealis and relatively good digestibility.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.4
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• pp.579-586
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• 2018

Short-term prediction of travel speed has been widely studied using data-driven non-parametric techniques. There is, however, a lack of research on the prediction aimed at urban areas due to their complex dynamics stemming from traffic signals and intersections. The purpose of this study is to develop a hybrid approach combining ensemble empirical mode decomposition (EEMD) and artificial neural network (ANN) for predicting urban travel speed. The EEMD decomposes the time-series data of travel speed into intrinsic mode functions (IMFs) and residue. The decomposed IMFs represent local characteristics of time-scale components and they are predicted using an ANN, respectively. The IMFs can be predicted more accurately than their original travel speed since they mitigate the complexity of the original data such as non-linearity, non-stationarity, and oscillation. The predicted IMFs are summed up to represent the predicted travel speed. To evaluate the proposed method, the travel speed data from the dedicated short range communication (DSRC) in Daegu City are used. Performance evaluations are conducted targeting on the links that are particularly hard to predict. The results show the developed model has the mean absolute error rate of 10.41% in the normal condition and 25.35% in the break down for the 15-min-ahead prediction, respectively, and it outperforms the simple ANN model. The developed model contributes to the provision of the reliable traffic information in urban transportation management systems.

• Journal of KIISE:Software and Applications
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• v.36 no.6
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• pp.451-461
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• 2009

The Adaptive Random Testing(ART) aims to improve the performance of traditional Random Testing(RT) by reducing the number of test cases to find the failure region which is located in the input domain. Such enhancement can be obtained by efficient selection algorithms of test cases. The ART through Iterative Partitioning(IP-ART) is one of ART techniques and it uses an iterative input domain partitioning method to improve the performance of early-versions of ART which have significant drawbacks in computation time. And the IP-ART with Enlarged Input Domain(EIP-ART), an improved version of IP-ART, is known to make additional performance improvement with scalability by expanding to virtual test space beyond real input domain of IP-ART. The EIP-ART algorithm, however, have the drawback of heavy cost of computation time to generate test cases mainly due to the virtual input domain enlargement. For this reason, two algorithms are proposed in this paper to mitigate the computation overhead of the EIP-ART. In the experiments by simulations, the tiling technique of input domain, one of two proposed algorithms, showed significant improvements in terms of computation time and testing performance.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.287-295
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• 2010

In this study, ordinary Portland cement was used and the air void was minimized by using minute quartz as the filler. In addition, steel fibers were used to mitigate the brittle failure problem associated with high strength concrete. This study is in progress to make an Ultra-high strength powdered concrete (UHSPC) which has compressive strength over 300 MPa. To increase the strength of concrete, we have compared and analyzed the compressive strengths of the concretes with different mix proportions and curing conditions by selecting quartz sand, dolomite, bauxite, ferro silicon which have diameters less than 0.6 mm and can increase the bond strength of the transition zone. Ultra-high strength powdered concrete, which is different from conventional concrete, is highly influenced by the materials in the mix. In the study, the highest compressive strength of the powdered concrete was obtained when it is prepared with ferro silicon, followed in order by Bauxite, Dolomite, and Quartz sand. The amount of ferro silicon, when the highest strength was obtained, was 110%, of the weight of the cement. SEM analysis of the UHSPC showed that significant formation of C-S-H and Tobermorite due to high temperature and pressure curing. Production of Ultrahigh strength powdered concrete which has 28-day compressive strength upto 341MPa has been successfully achieved by the following factors; steel fiber reinforcement, fine particled aggregates, and the filling powder to minimize the void space, and the reactive materials.

• Journal of Preventive Medicine and Public Health
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• v.32 no.3
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• pp.400-414
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• 1999

Objectives: This is a descriptive study which was carried out to identify characteristics of the chronic mentally ill and their families in a rural area and the influencing factors on family burden. Methods : Data was collected for seven months beginning April 1, 1998 by questionnaire from chronic mentally ill patients and their families in two towns and seven townships of the rural areas of Kyonggi Province. In additional to the mental diagnosis of the mentally ill patients, family burden was measured by interviewing the other family members using the questionnaire developed by Pai & Kapur (1981). Of those interviewed, 103 patients were selected for final analysis. Results : Of 103 mentally ill patients, 36.1% of the subjects were not under treatment. In particular, of 29 patients with schizophrenia, 48.3% of the subjects had stopped taking medication and 6.9% of the subjects had never been treated. According to the results of a specialized examination by a psychologist, 81% of patients were in need of Hospitalization. Most primary caregivers were parents. Of the 101 primary caregivers in the study, 39.6% were over 65 years old. In case of death of the primary caregiver, 50.5% of these 101 mentally ill patients would not have anyone to care for them. Of the various kinds of family burden, primary caregivers most often reported psychological stress. Overall, the families of dementia and schizophrenia patients complained of the most family burden. Through univariative analysis, the variables of sex, education and current treatment type of the patients, the relationship with the patient and marital status of the primary caregiver and the number of people living together in the household showed significant correlation with the family burden of schizophrenia patients. Univariative analysis also showed that there were a number of variables which were correlated to the family burden in mentally retarded patients. Concerning the need for mental health services, the most common requests were for entitlement to disability benefits and housing programs. Conclusions: Community mental health services in rural areas must be developed, planned and executed in consideration of the local situation. In particular, the development of various family support programs is needed in order to mitigate emotional, mental and economic burdens and carry out a positive role to care for and rehabilitate patients.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.141-149
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• 2009

This study was conducted to investigate the causes that induce the T-shape cracks at the joints in the jointed concrete pavements(JCPs). The finite element models of JCP including dowel bars were developed and the stress distribution in the slab was investigated under environmental loads. To investigate the effect of dowel bars on the transverse stresses at the joints that induce the T-shape cracks, the slab curling behavior was analyzed with and without dowel bars. In addition, the stress concentration was investigated when the dowel bar was not installed at the mid-depth of the slab. The results of this study showed that the transverse stresses were not affected by the dowel bars if the dowel bars were installed at the mid-depth of the slab. However, if the dowel bars were not installed at the mid-depth, the transverse stresses were concentrated at the dowel bar locations when the slab curled. The stress concentration was dependent on the contact characteristics between the dowel bar and concrete, and was significantly large when the dowel bar not installed at the mid-depth was located far from the edge of the slab. Therefore, to mitigate T-shape cracking in JCP, dowel bars should be very carefully installed and leveled at the proper locations.