• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.2
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• pp.178-188
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• 2019

When using a distributed system, it is very important to know the intention of a target ship in order to prevent collisions. The action taken by a certain ship for collision avoidance and the action of the target ship it intends to avoid influence each other. However, it is difficult to establish a collision avoidance plan in consideration of multiple-ship situations for this reason. To solve this problem, a Distributed Stochastic Search Algorithm (DSSA) has been proposed. A DSSA searches for a course that can most reduce cost through repeated information exchange with target ships, and then indicates whether the current course should be maintained or a new course should be chosen according to probability and constraints. However, it has not been proven how the parameters used in DSSA affect collision avoidance actions. Therefore, in this paper, I have investigated the effect of the parameters and weight factors of DSSA. Experiments were conducted by combining parameters (time window, safe domain, detection range) and weight factors for encounters of two ships in head-on, crossing, and overtaking situations. A total of 24,000 experiments were conducted: 8,000 iterations for each situation. As a result, no collision occurred in any experiment conducted using DSSA. Costs have been shown to increase if a ship gives a large weight to its destination, i.e., takes selfish behavior. The more lasting the expected position of the target ship, the smaller the sailing distance and the number of message exchanges. The larger the detection range, the safer the interaction.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.21-36
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• 2019

To ensure that Korea continues to grow, past governments have been consistent in following a policy of advancing into Russia, Mongolia, and Eurasia. The northern economy can expect to achieve synergistic growth because its economic structure complements that of Korea, which has high energy demand and industrial development. There is also an opportunity to accelerate the growth of the China-Russia-Mongolia economic corridor, which is based on Russia's Look East Policy, China's One Belt One Road, and the Mongolian Steppe Road initiative. The Korean government is pursuing a New Northern Policy to achieve the goal of economic cooperation and peace building with other nations, including North Korea; this policy succeeds the Northern Policy pursued by the previous government. As international economic cooperation requires transportation infrastructure, the demand for shipping, which offers more advantages than road and rail transportation, will increase; thus, it is necessary to prepare for it. Korea's port cities, which have a port that serves as the nodal point for maritime transportation, need to prepare for the New Northern Policy. In this paper, the long-term development of Seosan-Daesan port in the was planned and the North Korea's opening-op plan was considered in accordance with the New Northern Policy. Because international cooperation between the government and the provincial cities is required, cooperation with the Port Authority is needed, along with the proactive attitude of Seosan City, Chungcheongnam-do. The Seosan-Daesan port, which is the center of the liquid energy cargo center, can become the base of the New Northern Policy Region; further, the port can be an opportunity to establish its position as a peaceful economic hub on the west coast of Korea.

• Management & Information Systems Review
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• v.38 no.3
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• pp.113-125
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• 2019

This study empirically analyzes the effect of SNS informativeness, playfulness and reliability on purchase intention and the effect of consumer's purchase intention on business performance through structural equation model, In doing so, this study aims to suggest ways to enhance consumers' purchase intention and consequently increase the business performance through various SNS marketing strategies that can efficiently manage consumers. The questionnaires were distributed to adult men and women who are in their 20s through 60s, actively use SNS, and primarily reside in Daegu and Gyeongbukdo. The 400 copies of questionnaire were distributed from September 15 to October 1, 2018, of which 364 (91%) were used for the empirical analysis, except for 36 of the questionnaires that were unfaithful or unresponsive. Basic statistical analysis including frequency analysis was performed using SPSS 22.0 and AMOS 24.0, reliability and validity analysis were also performed, and finally hypotheses were tested by performing confirmatory factor analysis and path analysis of structural equation model. All of the SNS informativeness, playfulness and reliability were shown to have positive effects on the purchase intention. In addition, the effect of purchase intention on business performance was found to be significant. Companies should come up with a strategic SNS marketing plan to encourage consumers to enhance the willingness to purchase their products and services through SNS, and to make actual purchases, thereby improving business performance.

• Korean Journal of Heritage: History & Science
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• v.47 no.4
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• pp.4-21
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• 2014

Korean government has taken positive policies, including making "An Basic Plan on the Conservation and Activation of the Royal Tombs of the Joseon Dynasty, UNESCO World Heritage", since 40 royal tombs of the Joseon Dynasty were inscribed as UNESCO World Heritage in 2009. However, projects utilizing the royal tombs of the Joseon Dynasty are in the beginning step and very few has been researched on those projects academically. This study analyzed total 311 projects utilizing the royal tombs of the Joseon Dynasty, which have been made by the Cultural Heritage Administration of Korea from 2009 to 2014, through the literature review and content analysis methodology. An analysis frame consists of educational, touristic, compound and industrial activation on the basis of the utilization types made by the Cultural Heritage Administration of Korea. Most projects utilizing the royal tombs of the Joseon Dynasty are in the very beginning step in terms of educational and touristic utilization. No project utilizing the royal tombs of the Joseon Dynasty in terms of industrial utilization is found. Those projects are almost similar without distinctive characteristics peculiar to each royal tombs. Most projects have been taken on the short term level and the budget size for those is not enough. Projects are mostly focused on the on-site of royal tombs with little paying attention to converging projects utilizing digital and on line techniques. Some suggestions are the followings: increase of the budget on projects utilizing the royal tombs of the Joseon Dynasty, development of content peculiar to each tomb, development of industrial projects, development of converging projects utilizing digital and on line techniques, establishment of new medium and long term plans for utilization of the royal tombs of the Joseon Dynasty and so on.

• Korean Journal of Heritage: History & Science
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• v.48 no.4
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• pp.94-109
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• 2015

This study examines Korea's revitalization policy on the ancient capital cities, which has been set out for preserving and improving living quality of the local communities. Since it was established, the policy has faced with constant challenges such as the lack of funding for preservation and revitalization of local communities. This study aims at providing a set of recommendation on the problems on the policy. In order for the study, it takes objective and empirical analysis on the problems of the policy by executing survey on the satisfaction level of the stakeholders and policy-makers on the present policy. The survey has displayed that the government needs to 1. subsidize more budget, 2. set out a policy to reduce the inconvenience of local communities 3. establish a supportive program to help the present promotion policy. In addition, the survey analysis has proved that the elements of revitalization policy affect to the increase of satisfaction. It concludes with a set of recommendation, 1. to secure sufficient budget to implement the policy; 2. to reduce a restriction of individual rights; 3. to promote the supporting program of local community; 4. to establish governance system with officers, experts, residents, and research institutes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.452-460
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• 2019

Exposure to heavy metals through the consumption of contaminated seafood poses a health risk to humans. In Korea, seafood imports are increasing with consumption, with the largest increase in imported seafood coming from Russia. Peter the Great Bay and the Razdolnaya River are both major fisheries and protected areas under the Northwest Pacific Action Plan located near Vladivostok, Russia. This study analyzed heavy metal [cadmium (Cd), lead (Pb), total mercury (tHg), and total (tAs), and inorganic (iAs) arsenic] concentrations in shellfish and crustaceans collected from these areas. Except for iAs, the major toxic heavy metal concentrations of the samples met the national standards (Cd, 0.024-0.982 and 0.003-0.379 mg/kg; Pb, 0.021-1.533 and 0.002 mg/kg; tHg, 0.006-0.015 and 0.036-0.097 mg/kg). The tAs concentrations of three samples exceeded the Russian standard (5 mg/kg, wet weight), whereas the iAs concentrations were extremely low (ND-0.033 mg/kg). Compared with the provisional tolerable weekly intake (PTWI) of the Ministry of Food and Drug Safety and Joint FAO/WHO Expert Committee on Food Additives, the percentages of PTWI of Cd, Pb, and tHg were 0.239%, 0.001-0.049%, and 0.013-0.302%, respectively. These findings reveal that there is no potential health risk by heavy metals through the consumption of Russian seafood obtained in the surveyed areas.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.1
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• pp.66-74
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• 2019

Excessive wear causes many complications when untreated, so that accurate diagnosis, analysis and predictive treatment plan should be made, and through evaluation of vertical dimension and stepwise treatment, a stable inter-arch relationship can be set. For the long-term success of implant treatment, ideal position and angle of implant is important, and its importance increases especially in multiple implant cases. Therefore, thorough diagnosis and planning, accurate surgery and prosthodontic procedures are significant. In this case, a 68-year-old male patient with a loss of vertical dimension due to multiple tooth loss and overall tooth wear was planned with systematic analyses from the pre-treatment stage to rehabilitate vertical dimension. Full-mouth fixed rehabilitation with computer tomography guided implant surgery was performed to the newly set vertical dimension and attained satisfactory outcomes both functionally and esthetically.

• The Korean Journal of Applied Statistics
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• v.32 no.1
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• pp.111-128
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• 2019

Subways are eco-friendly public transportation that can transport large numbers of passengers safely and quickly. It is necessary to predict the accurate number of passengers in order to increase public interest in subway. This study groups stations on Lines 1 to 9 of the Seoul Metropolitan Subway using clustering analysis. We propose one final prediction model for all stations and three optimal prediction models for each cluster. We found three groups of stations out of 294 total subway stations. The Group 1 area is industrial and commercial, the Group 2 ares is residential and commercial, and the Group 3 area is residential districts. Various data mining techniques were conducted for each group, as well as driving some influential factors on demand prediction. We use our model to predict the number of passengers for 8 new stations which are part of the 3rd extension plan of Seoul metro line 9 opened in October 2018. The estimated average number of passengers per hour is from 241 to 452 and the estimated maximum number of passengers per hour is from 969 to 1515. We believe our analysis can help improve the efficiency of public transportation policy.

• Clean Technology
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• v.27 no.3
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• pp.269-274
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• 2021

Bioenergy is generally considered to be one of the options for pursuing carbon neutrality. However, for a period of time, combustion of harvested plant biomass inevitably causes more carbon dioxide in the atmosphere than combustion of fossil fuels. This paper proposes a method that predicts and minimizes the total amount and payback period of this carbon debt. As a case study, a carbon cycle impact assessment was performed for immediate switching of the currently used fossil fuels to biomass. This work points out a fundamental vulnerability in the concept of carbon neutrality. As an action plan for the sustainability of bioenergy, formulas for afforestation proportional to the decrease in the forest area and surplus harvest proportional to the increase in the forest mass are proposed. The results of optimization indicate that the carbon debt payback period is about 70 years, and the carbon dioxide in the atmosphere increases by more than 50% at a maximum and 3% at a steady state. These are theoretically predicted best results, which are expected to be worse in reality. Therefore, biomass is not truly carbon neutral, and it is inappropriate as an energy source alternative to fossil fuels. The method proposed in this work is expected to be able to contribute to the approach to carbon neutrality by minimizing present and future carbon debt of the bioenergy that is already in use.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.633-642
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• 2021

Growing demand for electricity, when combined with the need to limit carbon emissions, drives a huge increase in renewable energy industry. In the electric power system, electricity supply always needs to be balanced with electricity demand and network losses to maintain safe, dependable, and stable system operation. There are three broad challenges when it comes to a power system with a high penetration of renewable energy: transient stability, small signal stability, and frequency stability. Transient stability analyze the system response to disturbances such as the loss of generation, line-switching operations, faults, and sudden load changes in the first several seconds following the disturbance. Small signal stability refers to the system's ability to maintain synchronization between generators and steady voltages when it is subjected to small perturbations such as incremental changes in system load. Frequency stability refers to the ability of a power system to maintain steady frequency following a severe system upset resulting in significant imbalance between generation and load. In this paper, we discusses these stability using system simulation by renewable energy deployment plan, and also analyses the influence of the renewable energy sources to the grid stability.