• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.157-167
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• 1998

The distribution of particulate organic carbon and nitrogen (POC and PON) and chlorophyll a of particulate organic matter was investigated in the southwestern East Sea in August and October 1995. The upwelled 'cold water mass' with temperature less than 14$^{\circ}$C occurred near the Campo coast in August. At most of the onshore stations, concentrations of POC and PON were high in surface water, rapidly decreased with depth down to 30 m and then remained constant. Differences in their concentrations between surface and bottom waters were larger in August than in October. At the offshore stations, POC and PON were higher in surface than in deep waters though the differences in concentration were small. The highest, vertically integrated inventories of POC, PON and phytoplanktonic carbon in the upper mixed waters of the onshore stations occurred in August. The mixed layers at onshore stations showed relatively high percentages of POC, PON and chlorophyll a in total suspended matter, low ratios of POC to chlorophyll a and high inventories of phytoplanktonic carbon, compared with the values at offshore stations. These phenomena were more obvious in August, when cold water mass developed strongly, than in October. These results indicate that primary production plays a significant role for the budget of particulate organic matter in the upwelled cold water mass of the southwestern East Sea.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.257-264
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• 2003

Bulking change between sediments and dredged soils occurs when dredged soils are fully disturbed by dredging process and settled down to stabilized conditions in the basin. Bulking of dredged soils are affected by chemical injection, coagulant and flocculant, to speed up settling process of the suspended solids. In this paper, bulking changes of dredged soils are investigated by experimental works regarding injection effects of the coagulant and flocculant. Dredged sediments were sampled in the lagoon located at the East Coast, and the bulking change of dredged soils is quantitatively analysed by changing the clay content and the amount of the coagulant and flocculant. The optimal amounts of the coagulant and flocculant are determined based on minimal bulking change due to coagulant and flocculant injection. From the experimental results, the bulking of dredged soils increased 1.69 times on the average and the bulking change rate slightly increased as clay content increasea due to injection of the coagulant and flocculant.

• Journal of Navigation and Port Research
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• v.33 no.9
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• pp.645-651
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• 2009

In this study, a series of laboratory experiments were carried out to investigate the weak reflection of regular and random water waves over a train of protruded permeable shore structures. A cylindrical slit type breakwater and the alternatives are employed and compared for reflecting and transmitting capabilities of incident waves including wave forces. A series of random waves were generated by using the Bretschneider-Mitsuyasu frequency and directional spectrum. Measured spectrum of irregular waves without breakwaters is verified by comparing with those of the input waves generated. Weak reflection is occurred at the breakwater center of the peak frequency. If the row of breakwaters is fixed at three layers and the relative height of breakwater is fixed at 0.6, around 45% of incident wave energy is reflected to offshore. It is also found that the transmission of directional random waves increases as the maximum frequency parameter increases. A very good agreement is observed. Reflection coefficients of permeable submerged breakwaters are less than those of impermeable breakwaters. The upside-down L shape is recommended for a small fishery harbor mooring in terms of reflecting capability and of practical application. The final design was applied to the wharf of a small beach of Seolly, near Namhae at the southeast coast of Korea.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1549-1560
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• 2016

Today, all the countries of the world newly recognize importance of sea, which are focused on efforts for security of marine territory and fishes resources. Many of the coastal state, to strengthen the rights of their own country EEZ, marine survey and continental shelf development, travels through such maritime jurisdiction in the territorial sovereignty and the EEZ overlaps, deepening complex interests between neighboring countries cooperation activities of the fierce competition, the domestic and foreign been has been carried out. Under such circumstances, is devastated coastal of China, our territorial waters and EEZ has been violated more and more, in spite of the powerful crackdown maritime public power, illegal fishing more resistance intensified. They tend to be gradually organization, collectivization and atrocities. Currently, illegal fishing of Chinese fishing boats in the West Sea of Korea, including the waters near Yeonpyeong Island is prevalent as operating in the coast of the country. Furthermore regrettable one is illegal on a scale and the situation where South Korea of scale of damage caused by it have not been accurately grasp of the operation, but that there is damage of Korea official duty enforcement to crack down the increase to illegal operations year after year have occurred. Violent, illegal fishing of Chinese fishing boats, in order to eradicate the operations of insane at our sea, we investigated to the infringement situations of fisheries resources by multiple fields. each of problems presenting a specific preservation plan in accordance with the function and role of the maritime enforcement organization and other government organization the point. at the same time we will try to seek measures such as a scheme that it is possible to increase the capacity.

• Journal of Aquaculture
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• v.10 no.4
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• pp.457-462
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• 1997

During the period of the Cochlodinium polykrikoides red tide occurrence in the southern coast of Korea in 1997, we obseved the vertical migration of red tide organisms in situ, along with environmental factors such as water temperature, dissolved oxygen, pH, chlorophyll $\alpha$ and nutrients for practical application of loess suspension techniques ot diminish fisheries damage. To cope with serious outbreaks of red tide of C. polykrikoides, the finfish culturists resorted with loess suspension to disperse the bloom watermass by turning around it with fishing boats in full speed. Peak in afternoon the cell numbers were diminished in the surface layer after sunset red tide organisms settled down in the middle and bottom layer progressively again after sunrise. Chlorophyll $\alpha$ and dissolved oxygen showed the same trends of variation with the cell number. In the course of controlling the red tide with loess suspension we could not find any severs oxygen deficiency to kill the culture species.

• Tribology and Lubricants
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• v.35 no.2
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• pp.114-122
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• 2019

High-speed rotating machinery requires low cost and reliable bearing elements with low friction, stable rotordynamic characteristics, and a simple design. This study experimentally evaluates the effects of bearing-support elements on the vibrational characteristics of a small-sized, high-speed permanent magnetic motor. A series of coast down tests from 100 krpm characterize the vibrational behaviors, rotor displacement, and housing acceleration of motors supported by ball bearings, ball bearings with a metal mesh damper, and gas foil bearings, respectively. Two eddy-current sensors installed in the horizontal and vertical directions measure the displacement of the rotor at its front nut, and a 3-axis accelerometer attached to the motor housing measures the housing acceleration. The test results reveal that synchronous (1X) vibration components most significantly affect the rotor displacement and housing acceleration, independent of the bearing-support elements. The motor supported by the deep-groove ball bearings results in the largest rotor vibrations increasing with speed; this is due to the absence of a damping mechanism. Additionally, the metal mesh damper effectively reduces the rotor displacement, housing acceleration, and sound-pressure level in the high-speed region (i.e., above 40 krpm), thus implying its substantial damping performance when installed on the outer race of the ball bearing. Lastly, the gas foil bearing supported motor yields the smallest rotor displacement, housing acceleration, and lowest sound-pressure level because of its hydrodynamic airborne operation, which does not require rolling elements that may cause mechanical friction and vibrations.

• The Korean Journal of Legal Medicine
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• v.42 no.4
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• pp.111-125
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• 2018

Statistical analysis was performed on national forensic autopsy data collected in the Republic of Korea, with the exception of Ulsan, during 2017. A total of 8,777 cases were categorized based on the region; information was provided by the Police Agency and the Coast Guard regarding sex, age, manner of death, and cause of death. Analysis of the manner of death revealed that 3,971 cases (45.2%) were unnatural deaths, 3,679 cases (41.9%) were natural deaths, and 1,127 cases (12.8%) were unknown deaths. Among the unnatural deaths, the majority of the cases (1,740 cases, 43.8%) were accidents, 1,316 cases (33.1%) were suicide, 385 cases (9.7%) were homicide, and 530 cases (13.3%) were undetermined deaths. Among the unnatural deaths, the majority of the cases (1,575 cases, 39.7%) were trauma, followed by 793 cases (20.0%) of poisoning and 689 cases (17.4%) of asphyxia. Falling down was the major cause of death by trauma (737 cases, 46.8%). As a result of the classification of asphyxia based on previous study, strangulation was the major cause, with 538 cases (78.1%). Among the natural deaths, heart disease was the major cause (1,790 cases, 48.7%), followed by vascular disease (697 cases, 18.9%).

• Tribology and Lubricants
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• v.38 no.5
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• pp.205-212
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• 2022

This paper presents experimental measurements of the structural characteristics of a two-pad beam-type gas foil journal bearing and its rotordynamic performance for a high-speed motor-driven turbocompressor. The test bearing had two top foils and two beam foils, each with an arc length of ~180°. Each beam foil was etched to obtain 40 beams with six geometries of different lengths and widths. The insertion of beam foils into the bearing housing produces equivalent beam heights. The structural tests of the bearing with a non-rotating journal revealed a smaller bearing clearance and larger structural stiffness for the load-on-pad configuration than for the load-between-pads configuration. Rotordynamic performance measurements during driving tests up to 100 krpm demonstrated synchronous vibrations and subsynchronous vibrations with large amplitudes. The test was repeated after inserting the shim between the top foil and beam foil to reduce the bearing radial clearance. The reduced bearing clearance resulted in a reduction in the peak amplitude of the synchronous vibrations and an increase in the speed at which the peak amplitude occurred. In addition, the onset speed and amplitude of the subsynchronous vibrations were dramatically increased and diminished, respectively. The rotor coast-down tests at 100 krpm show that the reduction in the bearing clearance extends the time to rotor stop, thus implying an improvement in hydrodynamic pressure generation and a reduction in bearing frictional torque.

• Strategy21
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• s.31
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• pp.190-219
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• 2013

Since Korea and Japan established diplomatic relationship, Relationship between Korea and Japan has not been easygoing. There are two most explosive, and noticeable ones among topics which have affected the relationship ; Dokdo and Historical Distortion. Without these issues, relationship between two countries will take a turn for the better. However, unfortunately, it seems that it is almost never going to happen. There is the Japanese conservative right-wing who has an influence on those two issues. The right-wing takes regard getting negative view or finding out dark past as an action from Self-torture view of history, and tries to dilute the Japanese sense of guilt on past invasions to neighbor countries. Moreover, to become a "normal country", they are trying to revise Constitution of the Japan so that Japan can possess the military and re-arm, dispatch troops abroad, and get the right to break the war. In other words, they expect Japan to become a powerful nation with great influence on Asia and world, as the period in which Japan conquered Korean peninsula, China, and South-Eastern nations. Japan still harbours secret romanticism for bygone days of imperialist glory. That is why neighbors want to never make the painful history happen again. In order to deal with this effort, most of all, it is required to assert better argument with a careful, thorough analysis on Japanese opinion about Dokdo. There might be a hidden card which can be accepted in the international society considering Japanese persistent effort to make Dokdo disputed area, and that is why we have to know that it is. In addition, it is needed to secure a high-quality professional manpower because the issues of Dokdo and Historical Distortion are primarily the matter of logic and references. The professional manpower should have open-minded to break down walls of their own majors. We have to introduce our achievements and stances to the international society vigorously. As a definite way to solve these problems, we have to develop national power. We have to possess naval forces and coast guard to protect our territory and Koreans overseas. There are not many options Korea can do to Japan, except protesting denunciation, and pressing a joint efforts. Most of the suggestions stated before are what have to be conducted domestically. It is a miserable condition, because two problems are Japanese domestic issues, but they become international issues and we have to seek a solution for ourselves.

• Journal of Aquaculture
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• v.9 no.3
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• pp.239-245
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• 1996

As one of the red tide control method, montmorillonite was used to eliminate the causative organisms in Korea and Japan. We assayed the loess to replace the montmorillonite because it distribute in large quantity and nearby the red tide occurrence in South Coast of Korea. By using the mixture of loess and coal ashes, we examined the decreasing level of nutrients such as ammonia and phosphate, the elimination of causative organisms as a chlorophyll a content, and the harmful effect on aquaculture orgarnisms in cage culture farms. Half of the ammonium and phosphate was adsorbed by the loess particles, but only $25\%$ of ammonium was adsorbed by the coal ashes particles. In water column test, the particles of loess and coal ashes were settled down by $80\%$ in 20 minutes, the red tide organisms was eliminated by $80\%$ after 2 hours in 1,000 ppm of loess suspension, but the organisms were eliminated only $30\%$ by the same concentration of coal ashes. The harmful test of fishes and invertbrates, we observed any other negative effects of test animals than a tint deceleration in yellowtail.