• Journal of Species Research
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• v.1 no.2
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• pp.249-256
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• 2012

Located 60 km from southern tip of Korean peninsula, Jeju is the largest Island in Korea and composed of volcanic habitat. Twenty-eight species of terrestrial mammals are listed from Jeju Island, of which 1 species and 3 subspecies are endemic. Also, 1 endangered species and 4 invasive alien species of land mammals are listed. Current status, brief history, management and conservation of the 28 species are discussed.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.274-276
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• 2001

A simple current controller for three-phase PWM power inverters using 3-level comparator is presented. All voltage vectors are accurately selected in order to minimize the current error using two three-level comparators and ${\alpha}-{\beta}$ current reference frame. The proposed algorithm have fast response and low current errors. This current controller is improved synchronization problem and increased the voltage utilization value. Usefulness of propose method are verified on the simulation result using Matlab/Simulink.

• Korean Journal of Environment and Ecology
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• v.21 no.2
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• pp.107-112
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• 2007

This study was carried out to investigate the herpeto-fauna at Hallasan National Park. We conducted a survey at 1100 Resting places, Eoseungsaengak, Donnaeko, Eorimok, Yeongsil, Gwaneumsa and Seongpanak from April, 2006 to January, 2007. A series of four families and 5 species of amphibians and 4 families and 8 species of reptiles were observed. Amphiesma vibakari ruthveni, Takydromus wolteri, Scincella vandenburghi, Coluber spinalis and Hynobius quelpartensis which are rarely appearing inland but they were frequently observed by this survey. Also, we observed Sibynophis chinensis that only inhabits Jeju island with in Korea. Jeju island has both southern and northern boundary lines for amphibians and reptiles. Amphibians and reptiles in Jeju island have a different from those inland and valuable information for biogeograpy due to dissimilar climate and isolation from continental for a long time. It is not certain whether some amphibians and reptiles, Bufo gargarizans, Rana rugosa, R. plancyi, Elaphe rufodorsata and Takydromus amurensis, inhabit Jeju island, as recorded in previous literatures, so the research on current status of them has to be carried out immediately.

• Korean Journal of Environment and Ecology
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• v.21 no.3
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• pp.235-242
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• 2007

In order to find out the current situation of the fauna of the mammals which inhabit Hallasan National Park, the areas of Seongpanak, Eorimok, Gwaneumsa, Yeongsil and Donnaeko were surveyed. The survey was conducted from April 2006 to January 2007 The analysis of geographical distribution revealed that there are 15 species of mammals, which belong to eight families and five orders, in which Apodemus chejuensis, Carpreolus pygargus tianschanicns, Rhinolophus ferrumequinum and Tamias sibiriricus barberi were found to be dominant species. It was also found that there exists the fauna of mammals in Mt. Halla such as Mustela sibirica quelpartis, Crocidura dsinezmi quelpartis, Micromys minutus hertigi and Sorex caecutiens hallamontanus, showing a bio-geological attribute that territorial population of taxologically geographical subspecies class exists. The fauna of the mammals in Jeju Island is rather simpler in its species composition in comparison with the inland of the Korean Peninsula ever since Jeju Island's geographical isolation from the mainland, mainly consisting of Chiroptera and small rodents.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.41-61
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• 1985

The purse-seine fishery is very important in the coastal fishery of Korea and the main fish species of this fishery are mackerals and also the main fishing grounds are Tushima Current region, To investigate the relationship between the fishing grounds of mackerels and oceanographic condition, the distribution of mean catches of mackerals of each size (1974~1982) was firstly examined and the oceanographic observation carried out in eastern and western area of Cheju island, being main fishing grounds, in July and October, 1983. The results are as follows: The main fishing grounds of mackerals were also in the Tsushima Current region in southern sea of Korea and the season of the good catches are in May and September to October. The small and medium size of mackerals of which the body lengths are 27 cm to 31 cm, about 2-3 ages, occupied about 90% but the smaller size mackerals of which body lenth is 22 cm (1 age)were about 40 to 70% in February to March. The locations of seasonal fishing grounds could founded by 15$^{\circ}C$ isotherm which indicates the Tsushima Current Water. With trace of this isotherm it was founded that the fishing grounds near the Korean Strait than that of south of Cheju island moves faster northward and/or later southward. The main fishing grounds eastward and westward of Cheju island were the front areas formed between the Tsushima Current Water and the southern coastal water of Korea or Yellow Sea Bottom Cold Water. And also the distributions of transparences, water colors and the penetration of sun light of this fishing grounds were similar to that of the temperature, the salinity or volume of planktonic organism.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.4
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• pp.247-254
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• 1991

Mackerel purse seine fishery is one of the most important fisheries in Korea and its annual mean catch from 1982 to 1988 is 350 thousand tons. Between 1982 and 1988, the characteristics of catch at 5 sectors of the sea area was analyzed according to operating sea block and the catch by fishes based on the data obtained from daily report of fishing condition that had been made out by 48 Korean fishing boats engaged in the fishery of purse seine. In these 5 sectors of the sea area, catch per net hauling in the coastal area of Cheju Island is less than that in the other sectors. Accordingly, the shape of fishing gear during operation has been measured to analyzed the deformation of net shape caused by the bottom current. (The lunar calender is used in the paper) The results obtained are as follows; The average CPUE of purse seines is 31.6 tons and it is higher from October to April than that from May to September. In the 5 purse seine fishing grounds, the ratio of net haul in the coastal sea area of cheju Island is 42.4% and it is the highest level, but the CPUE is 25.7 tons which is relatively low level. Each CPUE in the sea areas is significant differences with 1% level. Index of seasonal variation of mackerel CPUE from May to October is lower than the standard value, whereas index from November to January is higher. The diameter of circle by net shooting becomes shorter to the minimum caused by the bottom current during loose set, becomes narrower and the efficiency of fish encirclement becomes lower. The shape of leadline by bottom current becomes long oval type along with current direction in the tight set, while it becomes long oval type in the direction of a right angle to the current direction and the enclosed area is reduced hurriedly, and the deformation of net is most serious in the loose set.

• Journal of the Korean Society of School Health
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• v.30 no.2
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• pp.154-163
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• 2017

Purpose: This study aimed to understand the current situation of Korean adolescents' sexual experience and its characteristics by school level, gender, and related factors to their sexual experience. This could be the basic evidence for the development of various sex education programs for the youth. Methods: This study used the 11th online survey data on youth health behavior (2015) and all 68,043 students who participated in the study were included for the analysis. The binominal logistic regression model was used to identify the characteristics and relevant factors of sexual intercourse experience. Analysis was performed by complex sample design using SPSS/WIN 18.0. The statistical significance was defined as p<.05 with a two-sided test. Results: The factors related to sexual experience of adolescents included grade, sadness and hopelessness, smoking, Internet addiction, and sex education in school, for middle school boys. For middle school girls, grade, residence area, sadness and hopelessness, smoking, drinking, and sex education in school were related. For high school boys, the factors were grade, living with parents, economic situation, sadness and hopelessness, smoking, drinking, and Internet addiction. For high school girls, grade, sadness and hopelessness, smoking, and drinking were found to be related factors. Conclusion: The results of this study suggest that a practical program considering adolescents' level and characteristics should be developed and applied.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.1
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• pp.50-58
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• 1996

The authors carried out a field experiment to confirm the effect of underwater sound on the luring of fish schools in a setnet in the coast of Cheju Island. The effects of the acoustic emission on the luring of fish schools were observed using a manufectured underwater speaker in the setnet, and pure sound, of which frequency was 600Hz and the source level was 126dB, was emitted on and off at 5 minutes intervals in the set net during the night of ,July 29 and ,July 31. So we had recorded behavior of fish schools by the telesounder with two channel and shape of the setnet by underwater video camera and analyzed them. When the flood and ebb currents were around the setnet, the nets rised to the surface of water and it happened occasionaly at the stand of tide. Therefore, it was in the state that fish schools feel constraint to enter into the setnet, and was required a new design of the setnet stand up to strong tidal current. As the pure sound, of which frequency was 600Hz was emitted for the luring of fish schools in a setnet, the catch ammounts of fish, the young horce mackereWI'rachllrlls japonicus), was increased 4~6 times than not emitted.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.188-191
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• 2004

Appearance and disappearance of the China Coastal Waters(CCW) in the neighbouring sea of Cheju Island was very different yearly but usually appeared strongly in summer. At this time, sea level and salinity were varied in this area by the influence of the CCW. Satellite data(T/P;Topex/Poseidon) and Salinity (NFRID;National Fisheries Research and Development Institute) were used from 1993 to 2001. We compared with TG data of NOR I and TIP data in the observed station(33 31'N, 12632'E). Coefficient of correlation was 0.6~0.8 with the exception of 1993 and 1995. And variations of salinity was higher than $32.00\%_{\circ}$ in the southwestern part of Cheju Island and the southern part of the South Sea of Korea during June-October and SLA(Sea level Anomaly) was 10-11cm. Salinity of the southeastern part was higher than those of the southwestern part and SLA was 12~13cm because of the influence of Tsushima Current.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.72-77
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• 2005

The materials used in a ship screw propeller are commonly made with brass. The seawater corrosion and seawater cavitation of the screw propeller reduces the propulsive performance of the ship. In screw manufacturing, the corrosion rust of the screw propeller is removed through a hand grinding method. The grinding process produces dust of the heavy metals from the brass. The dust creates a poor working environment that is harmful to the health of the workers. An automatic corrosionrust removing apparatus, using a blasting method, was developed for the improvement of screw polishing conditions and its working environment. The performance of this apparatus was investigated by surface roughness, weight loss rate, hardness, electrochemical corrosion resistance, and cavitation erosion, after removing of the corrosion rust under various blasting conditions. Two medias of alumina and emery were used in this experiment. The surface roughness and hardness of the screw were improved by this apparatus. The electrochemical corrosion potential (Ecorr) and current density (Icorr) were measured by the dynamic polarization method, using a potentiostat,under the conditions of surface polishing with grinding, blasting, wire brushing, and fine sand papering. The test results prove that the new corrosion rust-removing apparatus improves the surface performance of a screw propeller.