• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.159-164
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• 2016

The goal of this study is to implement a communication system that can monitor the status of the nacelle using the power cable itself, without the dedicated communication lines such as an UTP cable and optical fiber for the offshore wind turbine. An inductive coupling powerline communication system for a MW class offshore wind turbine was proposed and its communication performance was demonstrated. The inductive couplers was designed for operation at up to 500 A using a ferrite composite materials. Field test was carried out on the wind farms of Jeju island. Using the iperf communication test program, we have obtained more than 15 Mbps data transmission rate through the 100 m power cable that was installed between the nacelle and the bottom of the power converter. In the data transmission stability test for a week, there was no failure ever. The minimum transmission rate was 15 Mbps and the average data rate was about 20 Mbps. Next, we have installed an infrared camera inside the nacelle in order to measure the temperature distribution and variation of the nacelle. The real-time thermal image taken by the camera was successfully sent to the monitoring system without error.

• Journal of the Korean Institute of Navigation
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• v.15 no.4
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• pp.41-58
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• 1991

The cooling degree days and the number of cooling days are used as important research materials not only in the field of design for building and cooling facilities but also in the government's establishment of energy policy. The purposes of this dissertation are to clarify the distribution of the cooling degree days and the number of cooling days by using the daily mean air temperature of 95 weather stations in Korea, and to show the distribution charts of the same cooling degree days and the same number of cooling days in order to help the practical uses of the materials. In cases of the base temperatures $24^{circ}C$, $25^{circ}C$, $26^{circ}C$, and $27^{circ}C$, the cooling degree days and the number of cooling days are shown in Table 5. The distribution charts of the same cooling degree days and the same number of cooling days are shown in Fig. 6 to Fig. 8 and Fig.9 to Fig. 11 respectively. As a result of this dissertation, Jeju Island and southern inland regions(especially Jeonju, Daegu, Gwangju) have a larger value than central regions and northern regions because of the influences of the terrain effect, and western coast regions have usually a larger value than eastern coast regions at the same latitude. The largest value appears in August of the year and the second in July, and the smallest in September. And southern inland area surrounded by Imshil, Goechang, and Boeun has a much smaller value than the other areas of its vicinity.

• Korean journal of applied entomology
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• v.47 no.1
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• pp.107-110
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• 2008

Tropical fire ant, Solenopsis geminata (Fabricius) is distributed over the tropical and temperate areas. It is a polyphagous pest attacking to various plant and causes the pain to the people doing outdoor work. So it is known for a hygienic pest to human being, especially the people doing outdoor activities. It can cause severe pain to human, even with just a bite. Of particular concern is the possibility of its settlement in this country, if it invade to the farmlands and/or forests of Jeju Island and southern part in Korea. It is listed as a regulated pest in Plant Quarantine Act of Korea. This ant is usually imported through a ship and early settled in the port area where it is already distributed. Recently its distribution is rapidly spreading into Southeast Asia and southern part of China. In Korea, it was detected the one time in 1990s, but was detected the ten times from 2000 to 2006 by an imported plant quarantine process. Therefore, we would like to provide some information on the species, including morphology, distribution, host plant, damaged symptom and its general bionomics, which will be useful data for plant quarantine process and control.

• Publications of The Korean Astronomical Society
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• v.19 no.1
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• pp.83-92
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• 2004

In this paper, we introduce the development of the large storage system in order to record the observed space radio signal in the Korean VLBI Network(KVN) with high-speed. The KVN is the Very Long Baseline Interferometery(VLBI) to observe the birth of star, the structure of space by constructing radio telescope with diameter 21m at the Seoul, Ulsan, Jeju from 2001 to 2007 years. To do this, Korea Astronomy Observatory joined the international consortium for developing the high-speed large storage system(Mark 5), which is developed by MIT Haystack observatory. The Mark 5 system based on hard disk has to record up to 1 Gbps the observed space radio signal. The main features of Mark 5 system are as follows; First it is able to directly record the input data to the hard disk without PC1(Peripheral Component Interconnect) internal bus, and the second, it has two hard disk banks, which are able to hot-swap ATA/IDE type very cheap up to 1 Gbps recording and playback. The third is that it follows the international VLBI standard interface hardware(VSI-H). Therefore it can be connect directly the VSI-H type system at the input/output. Finally it also supports e- VLBI(Electronic-VLBI) through the standard Gigabits Ethernet connection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2325-2331
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• 2012

Planar square-spiral antenna using a strip conductor is proposed and analyzed for RFID system in UHF band operating from 860MHz to 960MHz. By varying the length of common line, detached distance, strip line-space, strip line-width and the number of spiral turn, the optimized antenna are designed and fabricated in compact size without a matching-stub between the input port of the proposed antenna and RFID tag chip. From the optimized results, the frequency bandwidth in VSWR<2 has covered 100MHz in the RFID UHF band. The antenna gain has obtained 3.5dBi at the center frequency of 910MHz and the desired beam pattern has shown directional pattern on elevation and azimuth angle. Therefore, the proposed antenna is suitable for practical RFID applications requiring various tag chips with the specific input impedance.

• The Journal of the Acoustical Society of Korea
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• v.37 no.3
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• pp.129-138
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• 2018

In port and coastal areas where ship traffic is frequent, ship noise dominantly influences underwater noise in low frequency band below 1 kHz. In this paper, we propose a modeling method to estimate the underwater shipping noise using the voyage information of ship observed in AIS (Automatic Identification System). For the purpose of ship noise modeling, the navigation information of the vessels operating in the southern part of Jeju was observed using AIS and underwater noise was measured by installing a hydrophone in the experimental area to verify the modeled ship noise. AIS data were used to model the noise level of ship and compared with measured underwater noise. The variation of noise level with time was found to be similar, and the cause of the error was discussed. Through this study, it was confirmed that the noise level of ship can be estimated within 5 dB error range using AIS data.

• Journal of the Korea Society of Computer and Information
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• v.24 no.10
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• pp.65-70
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• 2019

In recently, ship trajectory data consisting of ship position, speed, course, and so on can be obtained from the Automatic Identification System device with which all ships should be equipped. These data are gathered more than 2GB every day at a crowed sea port and used for analysis of ship traffic statistic and patterns. In this study, we propose a method to process ship trajectory data efficiently with distributed computing resources using MapReduce algorithm. In data preprocessing phase, ship dynamic and static data are integrated into target dataset and filtered out ship trajectory that is not of interest. In mapping phase, we convert ship's position to Geohash code, and assign Geohash and ship MMSI to key and value. In reducing phase, key-value pairs are sorted according to the same key value and counted the ship traffic number in a grid cell. To evaluate the proposed method, we implemented it and compared it with IALA waterway risk assessment program(IWRAP) in their performance. The data processing performance improve 1 to 4 times that of the existing ship trajectory analysis program.

• The Journal of Fisheries Business Administration
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• v.53 no.3
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• pp.17-26
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• 2022

This study attempted to estimate the amount of expenditure per capita of visitors to the Mongsanpo fishing village tourism festival, and quantitatively measure how much the festival contributes to the local and national economy through input-output model. The analysis data used 302 questionnaires, excluding missing questionnaires, surveyed on festival visitors from April 21 to May 7, 2018, during the 9th Mongsanpo port webfoot octopus and seafood festival. The main results of this study can be summarized as follows. First, analyzing the average expenditure per person of festival visitors, it shows that the average one-person festival visitor consumes KRW 129,519: entertainment costs KRW 5,672 (4.4%), accommodation costs KRW 16,860 (13.0%), food costs KRW 74,791 (57.7%), transportation costs KRW 21,646 (16.7%), shopping costs KRW 6,788 (5.2%), and other costs KRW 3,762 (2.9%). Among the expenditures of festival visitors, the proportion of food expenses was the highest, and transportation costs and accommodation costs were in order. Second, based on the actual expenses spent by visitors at the fishing village tourism festival, the direct economic effect of the Mongsanpo fishing village festival was estimated be approximately KRW 14.8 billion. Third, as a direct and indirect economic impact effect of the Mongsanpo fishing village tourism festival in 2018, the amount of production induced in the local and national economies was estimated at KRW 33.3 billion, and the amount of value-added inducement was estimated at 11.3 billion won, and employment inducement reached 272 people, which is considered to contribute greatly to the national economy. This study quantitatively analyzes and provides the extent to which the fishing village tourism festival using local specialized fisheries directly or indirectly contribute to the local and national economy. Thus, it is expected to serve as useful information by providing basic information on business feasibility required for budgeting for local fishing tourism festivals.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.3
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• pp.275-285
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• 2010

Present state of nationwide marine facilities reported to 12 regional maritime affairs and port offices of MLTM in Korea for two years 2008 and 2009 was analyzed based on region and type of facilities, and national management plan was proposed in this study. As of the end of 2009, 8 types of marine facilities were reported to Yeosu regional maritime affairs and port office, while only 3 types of facilities were reported to Pohang, Daesan and Jeju regional offices, respectively. Oil and noxious liquid substances storage facilities belonged in the type of facility which was reported to all of 12 regional offices, and ranged from 11 facilities reported to Pyeongtaek regional office to the respective 38 facilities to Yeosu and Masan regional offices. In pollutants storage facilities, 4 facilities were reported to Masan regional office, 2 facilities to Donghae and Mokpo regional offices, respectively, 1 facility to Yeosu, Gunsan and Pyeongtaek regional offices, respectively, and none of facilities to the other regional offices. Ship construction, repair and scrap facilities belonged in the type of facility which was reported to all of 12 regional offices, and 45% of the facilities were concentrated in Southeastern Sea of Korea centering around Busan and Masan. In cargo handling facilities, 3 facilities were reported to Busan and Masan regional offices, respectively, 1 facility to Daesan regional office, and none of facilities to the other regional offices. In wastes storage facilities, 5 facilities were reported to Ulsan regional office, 4 facilities to Gunsan regional office, 2 facilities to Incheon regional office, 1 facility to Yeosu regional office, and none of facilities to the other regional offices. 65% of nationwide water intake and drainage facilities were concentrated in the areas of Pohang and Mokpo, and 78% of nationwide fishing spots at play were concentrated in the area of Masan. In other marine facilities, 4 facilities were reported to Donghae regional office, 3 facilities to Masan regional office, 2 facilities to Yeosu and Pyeongtaek regional offices, respectively, 1 facility to Incheon and Ulsan regional offices, respectively, and none of facilities to the other regional offices. In integrated marine science base facilities, 3 facilities were reported to Jeju regional office, 1 facility to Yeosu, Ulsan and Gunsan regional offices, respectively, and none of facilities to the other regional offices. The management based on the circumstances of regional offices, the management based on the characteristics of the type of facilities, the amendment of the relevant rules and regulations, facility owner's full knowledge and observance of the relevant rules and regulations with regard to the relevant type of facilities, and positive management actions from national point of view were proposed for national management plans of marine facilities.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.43-55
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• 2018

The biggest change in the field of coastal ship safety control since the accident of passenger ship Sewol has been the introduction of the maritime safety supervisor system. With its introduction, the safety control system in coastal passenger ships was changed from consisting of operation managers and marine police to operation managers and a newly-introduced maritime safety supervisor. The safety control system for coastal cargo ships was also converted from relying on ship inspection officers to having a maritime safety supervisor and ship inspection officers. However some negative elements have surfaced due to confusion related to the scope of work in the coastal cargo shipping field. These have been caused by dividing the supervisory agency, a lack of work continuity given non-permanent public official status, low supervisor qualifications overlooking reality, and limitations of the order for improvement to secure seaworthiness. It is essential that the maritime safety supervisor system be solidified to reinforce coastal ship safety control. Therefore, systematic safety control in the coastal cargo shipping industry should be conducted by a single, integrated government agency, and the area covered by the order for improvement to secure seaworthiness should be extended. Also limitations of the supervisor recruitment system due to non-permanent public official status should be simultaneously improved. In addition, it is necessary to upgrade supervisor qualifications to require experience with surveyors of international class, ship captains, and chief engineers.