• Journal of the Korean Institute of Navigation
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• v.18 no.3
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• pp.19-30
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• 1994

By use of the recent tropical cyclones' data in the Northwest Pacific Ocean, the occurrence frequency and region of typhoon as well as the features of the monthly mean track were analyzed. As the result of this study, (1) mean occurrence frequency of typhoon per year is 27.5, and 68% of total typhoons were formed in July to October and shown the highest frequency in August. (2) The ave-rage duration of typhoons is 8.5 days, and super typhoon which maximum sustained surface wind speeds is more than 130 knots occurs most frequently in October and November. (3) The highest frequency ap-pears around the Caroline, Mariana and Marshall Islands, and in wintertime, typhoon occurs in lower lati-tude comparing with those in summertime. (4) The typhoon track depends upon the distribution of pres-sure system and steering current in neighbouring areas. The mean track of typhoon can be classified into three types such as westward-moving type, northward-moving type and abnormally moving type. The west-ward-moving typhoons make landfall on the southern China by way of the South China Sea in June and July, on mid-part of China in August and September, and on Indo-china Peninsula in October and Novem-ber. The northward-moving typhoons approximately move on north~northwestward track to $20~30^{\circ}N$ from the occurrence region, then recurve to the East Sea through Korean Peninsula and Kyushu Island in June and July, to the Noth Pacific Ocean along the Japanese Islands in August and September and to the North Pacific Ocean through the seas far south off the Japan in October and November.

• Economic and Environmental Geology
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• v.23 no.1
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• pp.59-71
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• 1990

Magnetic anisotropy of a total of 213 independently oriented Tertiary rock samples from Pohang-Ulsan area has been studied. The sampled strata comprise basalts, tuffs and black shale, and range in age from Eocene to Miocene. The previous palaeomagnetic studies indicate that their magnetic carrier minerals are titanomagnetites. Among 23 sampled sites, 11 sites were found to preserve magnetic load foliation parallel to the bedding plane caused by the Iithostatic load of the overlying strata. Other 4 sites showed magnetic lineation indicating the flow direction of lava and tuffs. The remaining 8 sites revealed the magnetic tectonic foliation nearly vertical to the bedding plane. This magnetic foliation is interpreted to be generated by tectonic compression which acted nearly horizontally during the solidification stage of the strata. The compression directions deduced from the tectonic foliation of the 8 sites can be grouped into internally very consistent two group: a N-S trending one and the other WNW-ESE trending one. It is interpreted that the former N-S compression was associated with the N-S spreading of the East Sea(Sea of Japan) and the dextral strike-slip movement of the Yangsan-Ulsan fault system. The latter WNW-ESE compression is interpreted to represent the folding and reverse faulting activity in the Korean and Tsushima straits during middle/late Miocene times.

• Industrial Engineering and Management Systems
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• v.9 no.4
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• pp.294-302
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• 2010

There is a trend toward the world's manufacturing sites moving to East Asia. After manufacture, these products are transported to the advanced nations for their consumption demands. Among such advanced nations, the U.S.A. has the largest demand, and then Japan and European countries follow. It should be noted that the infrastructures of the Asian districts used for the production sites are rather limited, and the volume of products transported from these districts of Asia to the U.S.A is becoming tremendously large. This situation is causing very serious traffic problems. New products are required to be transported swiftly by air. Once the consumption and market demands are stable however, the products should be sent rather slowly, but in larger amounts. However, the airports of China are quite restricted in capacity, while the transportation volume is becoming large. As a result, transportation cost and the time required for transportation are increasing. Now, a third method is appearing. This is the so-called Sea and Air transportation. The cost and time in transit of this mode take mean positions between Air and Ocean services. At present there exists no well-thought-out strategy for how to allocate these three methods of transportation. This paper is an attempt to theoretically describe this mechanism and to discover the optimal way to allocate the three modes. For this purpose, several mathematical properties of value and cost of the products are defined, and on this basis a simulation of the transportation is established.

• Ocean and Polar Research
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• v.36 no.2
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• pp.189-197
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• 2014

The pearl-spot damsel, Chromis notata, is one of the important fishery species in Korea. While C. notata has been commonly harvested in southern Korea, the increasing number of C. notata in higher latitudes has crucial ecological, economic and evolutionary implications under conditions where the climate is rapidly changing. Here we examined the morphological and genetic characteristics of C. notata to assess patterns of geographical variations among the groups from three different sites. The groups were clearly distinguishable in the analysis of morphological characteristics. On the other hand, the groups were genetically indistinguishable. All individuals fell within a single clade in the neighbor-joining tree but appeared scattered in the haplotype network. Several haplotypes are shared among the sampling sites (Jejudo-Ulleungdo; Hap 9, Wangdolcho-Ulleungdo; Hap 28, Hap 33, Hap 34). Although control region markers did not elucidate the spatial patterns in genetic characteristics, Wangdolcho and Ulleungdo groups appear to exhibit a more robust gene flow between the two groups than with Jejudo group. Integrative approaches such as those combining morphological and genetic analyses minimize potential errors caused by limited perspectives of each analysis and can provide useful information for discovering functional DNA regions attributable to morphological characteristics expressions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.4
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• pp.363-367
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• 1986

Distributional patterns of Ulnung-do's Polychaetous annelid worms comprising 64 species out of 53 genera were divided into four zoogeographical groups with reference to the distribution of the world's polychaetous annelid worms; cosmopolitan, northern, temperate and tropical types. It was found out that there were 25 species of cosmopolitan type taking up $39\%$, 20 species of northern type, $31\%$, and 19 species of temperate type, $30\%$, but tropical type was not found. When compared with the polychaetous annelid worms of the neighboring coastal areas of the Yellow Sea, the east coast of U.S.S.R., Korea and Japan, those of Ulnung-do island were shown to have highest similarity to those of Yellow Sea follwed by the areas in the order named.

• Economic and Environmental Geology
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• v.18 no.2
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• pp.167-175
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• 1985

Geothermal heat flow distribution of Korea is investigated in the light of geophysical data, seismicity, tectonics and gravity as well as heat flow measurements and surface temperature of hot springs. The average heat flow in Korea is found to be $1.65{\mu}cal/cm^2{\cdot}sec$ that is greater than the world's average ($1.5{\mu}cal/cm^2{\cdot}sec$). The high heat flow is located at the regions of high seismicity in Korea. They are found to be Bugok of south central, and Haeundae, Pohang and Dongnae of the southest coast in the Peninsula. The anomalously high heat flow, equal to or greater than $1.93{\mu}cal/cm^2sec$ is found in the Kyongsang Basin, indicating that it is extended from the spreading of the East Sea (Japan Sea) and its origin.

• 한국해양학회지
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• v.21 no.3
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• pp.136-145
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• 1986

Biotope analysis(UPGM) of the data on the total benthic foraminferal assemblage (Kim and Han, 1982) collected from the southeastern sea off the Korean Peninsula shows that foraminiferal assemblages are related to the water masses prevailing in the study area. South Proper facies is governed by the Tsushima Warm Current, and Southern Deep facies is influenced by the cold water mass moved down along the bottom. Northern Nearshore facies is governed by the North Korea Cold Current, and North Proper facies is affected by the North Korea Cold Current and Japan Sea Proper Water. It is also evident that the upper part of the study area is under the influence of the North Korea Cold Current rather than the East Korea Warm Current which flows northward along/or off the right side of the study area. Planktonic foraminiferal occurrence also supports this biotope analysis.

• Geophysics and Geophysical Exploration
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• v.14 no.2
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• pp.127-132
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• 2011

We acquired and interpreted more than 650 km of high-resolution seismic reflection profiles in the Hupo Basin, offshore east coast of Korea at $37^{\circ}N$ in the East Sea (Japan Sea) to image shallow and basement deformation. The seismic profiles reveal that the main depocenter of the Hupo Basin in the study area is bounded by the large offset Hupo Fault on the east and an antithetic fault on the west; however, the antithetic fault is much smaller both in horizontal extension and in vertical displacement than the Hupo Fault. Sediment infill in the Hupo Basin consists of syn-rift (late Oligocene. early Miocene) and post-rift (middle Miocene.Holocene) units. The Hupo Fault and other faults newly defined in the Hupo Basin strike dominantly north and show a sense of normal displacement. Considering that the East Sea has been subjected to compression since the middle Miocene, we interpret that these normal faults were created during continental rifting in late Oligocene to early Miocene times. We suggest that the current ENE direction of maximum principal compressive stress observed in and around the Korean peninsula associated with the motion of the Amurian Plate induces the faults in the Hupo Basin to have reverse and right-lateral, strike-slip motion, when reactivated. A recent earthquake positioned on the Hupo Fault indicates that in the study area and possibly further in the eastern Korean margin, earthquakes would occur on the faults created during continental rifting in the Tertiary.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.186-194
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• 2000

bottom as a reference basis, some theoretical elements which form bottom echoes during acoustic survey of demersal fish were considered. A stable bottom detection method based on maximum voltage difference, which was not influenced by variable levels and waveform transformation. The method has been shown to be effective using in-situ bottom echo waveforms and computer simulation data. A comparison between near-bottom SV profiles acquired in Funka Bay, Hokkaido, of Japan, the East China Sea and the Yellow Sea, of Korea, with the threshold method and maximum differential voltage method, shows that the SV obtained with the maximum differential voltage method is 4-6 dB higher than those with threshold method within 2m from the bottom.

• Ocean and Polar Research
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• v.31 no.1
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• pp.121-131
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• 2009

In an effort to better understand the physiological and ecological differences between warm and cold water copepod species in Korean waters using lipid contents and compositions, two species of copepods (Pleuromamma sp. as a warm water species and Neocalanus plumchrus as a cold water species) were collected from the Northwest Pacific and East Sea/Sea of Japan, respectively. The cold water species showed two fold higher lipid contents than the warm water species (11% vs. 5% of dry weight). Wax esters, known as one of the major storage lipid classes, were found to be the dominant lipid class (accounting for 64% of total lipids) in the cold water species, whereas, in the warm water species, phospholipids, which are known as membrane components, were the dominant lipid class (accounting for 43% of total lipids),with a trace amount of the storage lipids as a form of triacylglycerols (${\leq}1%$ of total lipids). With regard to the fatty acid compositions, saturated fatty acids (SAFA), especially 16:0 (about 30% of total fatty acids), were most abundant in the warm water species, whereas the polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic acid (EPA : 20:5(n-3)) (${\geq}16%$ of total fatty acids), were most abundant in the cold water species. Among the neutral fraction of lipids, phytol, originating from the side chain of chlorophyll and indicative of active feeding on phytoplankton, was detected only in the warm water species. Significant quantities of fatty alcohols were detected in cold water species, particularly long-chain monounsaturated fatty alcohols (i.e. 20:1(n-9) and 22:1(n-11)), which are well known to abound in cold water herbivorous copepods. However, only trace amounts of short-chain fatty alcohols were detected in the warm water species. Twelve different kinds of sterols were detected in these copepod species, with cholest-5-en-$3{\beta}$-ol (cholesterol) and cholesta-5, 24-dien-$3{\beta}$-ol (desmosterol) dominating in cold and warm water species, respectively. In addition, for the warm water species (Pleuromamma sp.), we assessed the latitudinal gradients of lipid contents and compositions using samples from three different latitudinal regions (Philippine EEZ, Japan EEZ, and the East China Sea). Although no latitudinal gradients of lipid contents were detected, the lipid compositions, particularly dietary fatty acid markers, varied significantly with the latitude. The findings of this study confirm that the distribution of lipid contents and compositions in copepods may not only indicate their nutritional condition and diet history, but may also provide insights into their living strategies under different environmental conditions (i.e., water temperature, food availability).