• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio) provide specialized disaster radio communication services as a standard European for digital TRS(Trunked Radio System). Especially, DMO(Direct Mode Operation) feature is used effectively in the radio shadow areas which base station does not propagate radio signal because it can communicate directly with terminal to terminal without base station's relay function. However, to effectively used DMO feature, radio coverage prediction information should be provided to users. Therefore in this paper, we were calculated link budget of TETRA DMO terminals which were distributing and operating in the country and then predicted reaching distance about radio propagation to be applied with path loss model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.578-583
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• 2016

In order to provide a basis data for design of small arms and their silencer, an experimental study on firing noise of small arms was performed around the muzzle of a gun. For this experimental comparison analysis, the target small arms were included most operating small arms in our country. The sound pressure levels were measured at a certain distance which was predetermined according to US army firing test procedure, TOP 3-2-045. By this experimental study, the sound pressure levels of 5.56 mm caliber small arms are 143 dB ~ 145.4 dB and 7.62 mm caliber small arms are 144 dB ~ 145.2 dB. Between the heavy machine gun K12 and M60, the sound pressure level of K12 is slightly lower than M60.Also silencer for K14 snifer rifle was tested. Using this result, it has been found that the reduction effect of the silencer is 15.4 dB but the improvements of silencer performance in the high frequency range have to be studied later on.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.10 no.1
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• pp.57-61
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• 1980

In dental roentgenograph it is of mutual benefit to the patient and the dentist to use the minimum amount of radiation capable of producing roentgenograms with maximum interprtive informations. Recent increases in the number of diagnostic x-ray examinations made in this country have caused attention to be paid to the quantity of radiation delivered to the population and operator. The purposes of this study was to assess the quality of dental x-ray units, the amount of films, the average processing procedures and the radiation protection methods in korea. The results were as following: 1. Most of radiation generating system were used in low voltage such as 60Kvp, 10㎃. 2. High sensitivity films such as 'D' group of Kodak or Rinn were mainly used and average 14.7 films used per weeks. 3. Some dentists practiced visual processing technic in simple dark room, and others used instant films. 4. 68.26% of patient held the film themselves, but 27.30% were assisted by dentists film holding. 5. In radiation protection method, 7.85% of dentists had protection equipments such as protective barrier, 2.73% wore protective apron, 27.9% made it a rules to avoid beam, and 7.51% used to maintain a distance from the radiation source.

• Journal of the Korea Fashion and Costume Design Association
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• v.8 no.1
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• pp.37-48
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• 2006

The purpose of this study was to identify Intra-industry phenomena of Clothing Trade in Korea. For this purpose, changes of Korean clothing trade were analyzed in connection with the theory of intra-industry trade during the 1990's. Formerly, changes of Korean clothing trade were analyzed by the trade orientation index and that of the trade with each Korean clothing trade partner particularly. secondly, tendency and major determinants of two-way trade or intra-industry trade of Korean clothing trade were analyzed. The results of the study were as follows : First, the trade pattern of clothing in Korea was strong export orientation. Since the mid 1990's, however, this tendency has been weakened. Second, tendency of one-way trade is strong generally. but since the mid 1990's, tendency of intra-industry(two-way) trade increased. The intra-industry(two-way) trade tendency with Hong Kong and China is especially strong. Third, from the viewpoint of determinants of intra-industry trade in clothing industry, the determinant is distance between countries in 1994. Also the determinant is trade tendency of the country in 1999.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.2
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• pp.155-161
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• 1994

Accurate positioning method using low cost GPS modules is proposed, which use the technique of differential GPS. DGPS experiments have been made using two coarse-acquisition (C/A) code GPS modules. Position accuracy of better than 5 m was obtained for position dilution of precision (PDOP) of 2-3 and that of better than 10 m after filtering was obtained for PDOP of about 9 in a local area. Static DGPS experiments were performed at Kookmin university with the DGPS correction data of KRISS reference station at Taejon. The distance between two stations is about 140 km. The results show that precision of the position is about 10 m (2 drms), which is ten times better than the results with the GPS module alone. Accuracy of about 10 meters can be obtained in near real time by the DGPS service with a reference station in our country.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.286-293
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• 2000

This paper treats performance analysis and improvement of DSRC physical layer which is discussed for standardization at the ISO TC-204 WG-15. DSRC is a short range wireless communication for which distance is less than 100m between RSU and O BE, since DSRC requires cheap and simple modulation technique, ASK is being developed as standard modulation system among PSK, FSK and ASK in our country. This paper analyzes the performance of DSRC physical layer system which is at the first stage of development under Rician fading channel, more sepcifically, the validity of the system and the performance limitations are shown. Both equalizer and antenna diversity techniques are simulated to improve the ASK system performance.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.83-92
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• 2003

The previous control point surveying, being standardized by trigonometric point which hasn't been unified in the whole country and producing put into operation through complex calculation process, has many problems about accurate results and economic side. Because most of trigonometric points that standardize a present surveying are in situation in top of the mountain, there are many difficulties in solving sight problems. Since trigonometric points are far away from one another, Differences are created because of limitation of point distance, observatory network construction and distribution of error. In the information age, the study about acquiring three dimension surveying information that uses GPS has been processed as fast as acquiring topography information is getting important gradually. For utilizing GPS in surveying work, deciding transformation 7-Parameters that changes data about location information which is received by GPS receiver is important. In this study, it is decided transformation 7-Parameters that can be used in ka-pyoung area by using GPS surveying production that had put into operation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.703-711
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• 1992

As the underground area of the metropolitan becomes denser recently, an introduction of forced cooling system is under study to maximize the carrying capacity of existing cables in tunnels. Indirect water cooling system laid within trough will probably be adopted for the next 345KV class underground power cables in this country. The system covers a distance of 1.5-3.0Km for one water cooling interval and one water cooling interval is composed of several sub-sections that have different thermal analysis conditions. Thus the distribution of temperature in each sub-section is described by different conditions in general. In this paper a method that can accurately match the temperature of the coolant in the boundary between sub-sections has been suggested. An algorithm to find the temperature distributions effectively in the thermal system has also been presented. A computer program using this method has been tested in a smaple system and the results have shown the usefulness of this program.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.10a
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• pp.33-41
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• 2008

The longest tunnel has been halted at Daekwanryung by the failure of the host country of the Winter Olympiad in 2014, but modern High-Power TBM will come to Korea to excavate these long tunnels to establish the better horizontal connection between the western and eastern countries to improve the strong powerful logistic strategy of Korean peninsula. Train operation provides a key function of air movements in a long underground tunnel, and heat generation from transit vehicles may account of the most heat release to the ventilation and emergency systems. This paper indicates the optimal fire suppress services and safety provision for the long railway tunnel which is designed twin tunnel with length 22km in Gangwon province of Korea. The design of the fire-fighting systems and emergency were prepared by the operation of the famous long-railway tunnels as well as the severe lessons from the real fires in domestic and overseas experiences. Designers should concentrate the optimal solution for passenger's safety at the emergency state when tunnel fires, train crush accidents, derailment, and etc. The optimal fire-extinguishing facilities for long railway tunnels are presented for better safety of the comfortable operation in this hard rock tunnel of eastern mountains side of Korea. Since year 1900, hard rock tunnel construction has been launched for railway tunnels in Korea, tunnels have been built for various purposes not only for infrastructure tunnels including roadway, railway, subway, and but also for water and power supply, for deposit food, waste, and oils etc. Most favorable railway tunnel system was discussed in details; twin tunnels, distance of cross passage, ventilation systems, for the comfortable train operations in the future.

• International Area Studies Review
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• v.22 no.1
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• pp.61-78
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• 2018

Foreign subsidiary operation modes can be broadly divided into horizontal subsidiaries and vertical subsidiaries. According to institutional theory, foreign subsidiary operation mode differs depending on the host country institution. This study examines the effects of formal and informal institution on the foreign subsidiary operational mode of Korean firms. As a result of the empirical analysis, the higher the cultural distance and the lower political risks, the more favored the vertical foreign operation mode than the horizontal foreign operation mode. On the other hand, the higher the economic freedom and the lower corruption, the more favored the horizontal foreign operation mode than the vertical foreign operation mode.