• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.1
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• pp.1-11
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• 2021

In order to reuse existing onshore turbine foundations, it is important to redesign and reinforce the existing foundations according to the upgraded tower diameter and turbine load. In the present study, a slab extension reinforcement method and structure details of an anchorage part were examined in consideration of the reuse of spread footings, which are the most widely used foundation type in onshore wind turbine foundations. Experiments were conducted to evaluate the load resistance performance of a reinforced spread footing according to structure details of an anchorage part. The results showed that (1) the strength of an anchorage part could be increased by more than 30 % by adding reinforcement bars in the anchorage part, (2) pile-sleeves attached to an anchor ring contributed to an increase in rotational stiffness by preventing shear slip behavior between the anchor ring and the concrete, and (3) slab connectors contributed to an increase in the strength and deformation capacity by preventing the separation of new and old concrete slabs.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.575-587
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• 2020

Meteorological phenomena are observed by the Korea Meteorological Administration in a variety of ways (e.g., surface, upper-air, marine, ocean, and aviation). However, there are limits to the meteorological observation of the planetary boundary layer (PBL) that greatly affects human life. In particular, observations using a sonde or aircraft require significant observational costs in economic terms. Therefore, the goal of this study was to measure and analyze the meteorological factors of the vertical distribution of the see-land breeze among local meteorological phenomena using meteorological drones. To investigate the spatial distribution of the see-land breeze, a same integrated meteorological sensor was mounted on each drone at three different points (seaside, bottom of mountain, and mountainside), including the Boseong tall tower (BTT) at the Boseong Standard Weather Observatory (BSWO) in the Boseong region. Vertical profile observations for air temperature, relative humidity, wind direction, wind speed, and air pressure were conducted up to 400 m every 30 minutes from 1100 LST to 1800 LST on August 4, 2018. The spatial characteristics of meteorological phenomena for temperature, relative humidity, and atmospheric pressure were not shown at the four points. Strong winds (~8 m s-1) were observed from the midpoint (~100 m) at strong solar radiation hour, and in the afternoon the wind direction changed from the upper layer at the inland area to the west wind. It is expected that the analysis results of the lower atmospheric layer observed using the meteorological drone may help to improve the weather forecast more accurately.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.217-225
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• 2021

In this study, wave spectrum data were calculated using the water surface elevation data observed at 5Hz intervals from the HeMOSU-2 meteorological tower installed on the west coast of Korea, and wave parameters were estimated using wave spectrum data. For all significant wave height ranges, the peak enhancement parameter (γ_opt) of the JONSWAP spectrum and the scale parameter (α) and shape parameter (β) of the modify BM spectrum were estimated based on the observed spectrum, and the distribution of each parameter was confirmed. As a result of the analysis, the peak enhancement parameter (γ_opt) of the JONSWAP spectrum was calculated to be 1.27, which is very low compared to the previously proposed 3.3. And in the range of all significant wave heights, the distribution of the peak enhancement parameter (γ_opt) was shown as a combined distribution of probability mass function (PMF) and probability density function (PDF). In addition, the scale parameter (α) and shape parameter (β) of the modify BM spectrum were estimated to be [0.245, -1.278], which are lower than the existing [0.300, -1.098], and the result of the linear correlation analysis between the two parameters was β = -3.86α.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.3
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• pp.89-108
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• 2022

The purpose of this study is to reveal the specific current and future shapes of the collaborative network among organizations witch cope the COVID-19 in Korea. For this, this study conducted social network analysis, based on the response data of 73 experts from 36 COVID-19-related organizations. As a result of the analysis, it was confirmed that the Korea Disease Control and Prevention Agency (KDCA) plays a pivotal role as a control tower in coping COVID-19 in all of the analysis of degree, betweenness, and closeness centrality. In addition, the results revealed concrete forms of collaborative relationships among participating organizations in the public and private sectors that constitute the present and future networks centered on the KDCA. Furthermore, this study presented which organizations and relationships should be the focus of establishing a future collaborative network through comparative analysis between the current cooperative network and the network to be built in the future. The analysis results and discussions of this study are expected to be used as useful information for policy development related to collaborative networks that can effectively respond to disasters caused by new diseases in the future.

• Maritime Security
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• v.3 no.1
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• pp.237-255
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• 2021

This article analyzed maritime territorial policies in Korea. Marine territory originally refers to the topography of the subsoil in a country's territorial sea. From a political perspective, it is a broad concept that includes islands and polar regions beyond the jurisdiction of Korean sovereignty or sovereign rights, such as territorial waters, EEZs, and continental shelves. Also, Korean researchers use "maritime territory" as a term for maritime zones that stretch from Ieodo (Korean EEZ) to Dokdo Island. The purpose of this study is to review the concepts of various domestic maritime territories and examine the formation and change of policies. The article is structured as follows. Chapter 2 reviews past discussions on maritime territories and analyzes the concept of maritime territory based on them. The term "maritime territory" is used indiscriminately with islands due to the lack of discussion on this matter between academic circles in the past. Therefore, this chapter provides an in-depth analysis of the concept of maritime territory. Chapter 3 tracks the formation and change of maritime territorial policies. Today, the concept of domestic maritime territory has been completed in the public domain. The activities of the Ministry of Oceans and Fisheries, the control tower of domestic maritime territorial policies, are summarized to explain this concept. Chapter 4 analyzes the concept of maritime territory by comparing it with China's blue state territory (藍色國土). As China's concept of blue state territory has many similarities with maritime territory as a political base for China's maritime activities today, comparing these two concepts would be significant. Based on the above, Chapter 5 derives suggestions to promote maritime territorial policies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.59-67
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• 2022

In this study, the monthly airborne chlorides flying into the offshore bridges were investigated depending on the sea level. The target structures were 9 bridges located on the western and southern coast of South Korea. The airborne chlorides were measured at different sea levels on each bridge every month during 1 year. The results showed that the strongest seasonal wind from the northwest in winter expecially have led increase of the airborne chlorides, and its effect was more significant in the western coast than the southern coast. It was also found that the airborne chlorides declined with the increase of sea level. Three types of curves were suggested for analyzing the decrease trend with the sea level, based on the airborne chlorides at the lowest measurement height of main tower. The trend was varied depending on the sea area, and even in the same sea area, the local topographic condition affected the airborne chlorides. It means that the location and local topography should be considered simultaneously for durability management in the framework of the chloride source, and then the influence of the chloride source should be classified, e.g. safe and dangerous. From these results, it is expected that it could be used as baseline data for the evaluation of the deterioration environment in the Detailed guidelines for safety and maintenance of facilities [Performance evaluation]_Bridge.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.601-609
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• 2022

Jack-up drilling rigs are mobile offshore platforms widely used in the offshore oil and gas exploration industry. These are independent, three-legged, self-elevating units with a cantilevered drilling facility for drilling and production. A typical jack-up rig includes a triangular hull, a tower derrick, a cantilever, a jackcase, living quarters and legs which comprise three-chord, open-truss, X-braced structure with a spudcan. Generally, jack-up rigs can only operate in water depths ranging from 130m to 170m. Recently, there has been an increasing demand for jack-up rigs for operating at deeper water levels and harsher environmental conditions such as waves, currents and wind loads. All static and dynamic loads are supported through legs in the jack-up mode. The most important issue by society is to secure the safety of the leg structure against collision that causes large instantaneous impact energy. In this study, nonlinear FE -analysis and verification of the requirement against collision for 35MJ recommended by DNV was performed using LS-Dyna software. The colliding ship used a 7,500ton of shore supply vessel, and five scenarios of collisions were selected. From the results, all conditions do not satisfy the class requirement of 35MJ. The loading conditions associated with chord collision are reasonable collision energy of 15M and brace collisions are 6MJ. Therefore, it can be confirmed that the identical collision criteria by DNV need to be modified based on collision scenarios and colliding members.

• Journal of Navigation and Port Research
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• v.45 no.6
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• pp.306-313
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• 2021

National fishing harbour is as a refuge for fishing boats and a breakwater lighthouse is installed as a functional facility in consideration of harbour identification and the safety of passing vessels. In this study, the service level of breakwater lighthouse (234 units) was estimated based on the traffic volume of 105 national fishing harbour. For this purpose, the evaluation items were determined, the fishing harbour standard index was calculated (Fs=1), the proximity of fishing harbour was identified and the function (service level) of the breakwater lighthouse was estimated in the following order. However, national fishing harbour differed in size, traffic volume and fishing vessel capacity. Therefore, 105 national fishing harbour were divided into three groups through cluster analysis. The cluster analysis was based on the service level factors of the breakwater lighthouse, such as the number of weeding fishing vessels, tonnage of fishing vessels, the number of incoming and outgoing vessels per year, and fishing vessel capacity. As a result of the estimation, the service level of the breakwater lighthouse (light tower height, visual height, visual range, interval) was 10.50m, 16.50m, 7.00mile, 5.5sec for group 1, and 10.67m, 16.16m, 8.33mile, and 6.0sec for group 2, The three groups are 11.53m, 16.75m, 6.75mile and 5.0sec. The results of this study can be used as useful basic data for improving the service level of traffic vessels when a breakwater lighthouse is built in a fishing harbour in the future.

• Journal of Convergence for Information Technology
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• v.12 no.5
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• pp.116-125
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• 2022

Recent aspects of terrorism varies in various ways according to means, targets, and regions. In particular, the 9/11 terrorist attacks in the United States in 2001 changed the paradigm of each country's terrorism, and the South Korea also participated in the enactment and enforcement of the Anti-Terrorism Act in 2016. Based on this, CBRN terrorism is included in general terrorism, and the National Police Agency plays the role of a control tower, and a system supported by related organizations such as the Ministry of Environment is being built and operated. However, restrictions were confirmed in the organizational system, manpower composition, and equipment and materials in operation in preparation for CBRN within the police. Based on the identified limitations, we proposed improvement plans to strengthen the capacity for CBRN terrorism: establishing a dedicated CBRN organization; creating research organization; and securing additional dedicated personnel. Based on this, as an improvement plan to strengthen the capability of CBRN, the establishment of an organization dedicated to CBRN and a research organization within the National Police Agency, and expansion of electronic equipment suitable for the characteristics of CBRN were proposed. It is expected that the police's on-site response capability system for CBRN terrorism will be strengthened via the proposed improvement measures to recover the various restrictions on the response to CBRN terrorism.

• The Journal of the Korea Contents Association
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• v.22 no.9
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• pp.260-270
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• 2022

With the revision of the 「State Property Act」, the conditions for using state-owned land have improved. The new government is also suggesting the necessity of using state-owned land to revitalize private investment and secure financial investment capacity. In line with these policy changes, this study examines Japan's policy on the utilization of state-owned land and effective use cases, and seeks to find policy implications from the perspective of managing and promoting the use of state-owned land. The direction of Japan's public land utilization policy is to induce optimal use of state-owned land through efficient management, and to increase the value of state property by promoting active use of state-owned land through linkage of state-owned and public land and private participation, etc. It appears that the policy is being pursued in the direction of suppressing the sale of state-owned land in the country. To promote the effective use of state-owned land, it is necessary to establish a clear policy direction first. In addition, the establishment of a transparent information disclosure system and the establishment of a strong control tower capable of coordinating interests between ministries are required. The starting point of policy establishment for efficient use of state-owned land is to change the perception that the actual owner of state-owned land is the people.