• Ocean and Polar Research
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• 제28권3호
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• pp.317-329
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• 2006

To assess the contamination status of organochlorine pesticides in the marine environment of Saemangeum, surface seawater and sediments were collected and analyzed. Organochlorine pesticides were widely distributed in the Saemangeum environment, with DDT, HCH and endosulfan II contamination being particularly prevalent. The overall concentrations of DDTs, HCHs, and endosulfan II in surface seawater were in the rage of 0.03-0.65ng/l (mean value: 0.36ng/l), 1.31-4.54ng/l (2.63 ng/l), and not detected (ND)-0.96ng/l (0.49ng/l), respectively. Among the target organochlorine pesticides, endosulfan II showed the hi띤est level at the river mouth flowing into the Saemangeum. Additionally, its negative gradient from the rivers to the outside and a good correlation with $NO_3^-$ indicate that endosulfan ll inflows to the Saemangeum through the river; this conclusion is also supported by the elevated levels of endosulfan II in sediments at the river mouth. In sediment, the concentration of DDTs, HCHs, CHLs, and endosulfan II were in the range of 0.05-1.96 ng/g, 0.03-0.31ng/g, 0.01-0.13ng/g, and ND-0.62ng/g, respectively. Levels of contamination in Saemangeum are relatively lower than the median concentrations previously observed at the Korean coastal regions and sediment quality guidelines suggested by NOAA (Long et at. 1995).

• Ocean and Polar Research
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• 제28권3호
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• pp.339-352
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• 2006

Seasonal and tidal variations of density stratification in the Saemangeum waters are investigated based on synoptic CTD observations between July 2003 and September 2005. CTD data used in this study are those obtained after closing the dike No. 4 and before closing the two final gaps, the Sinsi and the Garyeok, on the Saemangeum tidal harrier. A total of 19 field campaigns comprehend a wide temporal spectrum, that is, few seasons, spring and neap tides, and high and low waters. In addition, ADCPs were anchored and CTDs were cast at three stations for 25 h in July 2005. Water columns are vertically homogeneous in autumn and winter. The vertical homogeneity persists in spring but with an occasional weak stratification in i:he northern part of the Gogunsan Islands. Increased reshwater runoff tends to stabilize the water columns and strong density stratification is established in summer. The mean potential energy anomaly (PEA) in summer used as a stratification parameter is the largest $(27.7\;J\;m^{-3})$ in the northern part of the Gogunsan Islands where the Geum River discharge dominates, the smallest $(16.9\;J\;m^{-3})$ is in the inner area of the barrier, in between the two $(21.6\;J\;m^{-3})$ in the southern part of the Gogunsan Islands. Whereas the stratification is generally strengthened in summer, strong winds or large tidal currents over the shallow depths frequently destratify the water column near the mouth of river runoff inside the tidal barrier. Periodic stratification, the development of stratification on the ebb and its breakdown on the flood, occurs in the mid-area inside the barrier induced by the tidal straining, which can also be found in the results of 25 h observation.

• Ocean and Polar Research
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• 제30권1호
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• pp.21-31
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• 2008

Analyzing the results of East Sea Regional Ocean Model using a 3-dimensional variational data assimilation scheme, we investigated spatial and temporal variability of the North Korean Cold Current (NKCC) in the East Sea. The climatological monthly mean transport of the NKCC clearly shows seasonal variation of the NKCC within the range of about 0.35 Sv ($=0^6m^3/s$), which increases from its minimum (about 0.45 Sv) through December-January to March, decreases during March and May, and then increases again to the maximum (about 0.8 Sv) in August-September. The volume transport of the NKCC shows interannual variation of the NKCC with the range of about 1.0 Sv that is larger than seasonal variation. The southward current of the NKCC appears often not only in summer but in winter as well. The width of the NKCC is about 35 km near the Korean coast and its core is located under the East Korea Warm Current. The North Korean Cold Water (NKCW), characterized by low salinity and low temperature, is located both under the Tsushima Warm Water and in the western side of the maximum southward current of the NKCC that means the NKCC advects the NKCW southward along the Korean coast. It is revealed that the intermediate low salinity water, formed off the Vladivostok in winter, flows southward to the south of $37^{\circ}N$ through $2{\sim}3$ paths; one path along the Korean coast, another one along $132^{\circ}E$, and the middle path along $130^{\circ}E$. The path of the intermediate low salinity varies with years. The reanalysis fields suggest that the NKCW is advected through the paths along the Korean coast and along $130^{\circ}E$.

• 멤브레인
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• 제23권1호
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• pp.80-91
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• 2013

$Fe(SO_4)_2$, cyclohexanedione dioxime, phenylboronic acid을 이용하여 금속 템플레이트 중합을 실시한 후 메탄올로 세척하여 Fe(II) clathrochelate 화합물을 합성하였다. Fe(II) clathrochelate와 polyethersulfone을 이용한 유무기 복합 멤브레인을 제조하였다. 멤브레인 제조를 위하여 Fe(II) clathrochelate는 DMF, NMP, DMAC와 같은 멤브레인 제조에 이용되는 극성 아프로틱 용매에 잘 녹는 물질로 고안되었다. Fe(II) clathrochelate는 trifluorosactic acid와 같은 강산 존재하에서도 금속이 분리되지 않고 안정성이 유지되었다. UV-vis 분광법으로 용액 가용성을 확인하였으며 (i) 강산 및 (ii) 경쟁 킬레이트제를 이용하여 용액상의 안정성을 확인하였다. 유무기 복합막은 PES, PVP, TSA, Fe(II) clathrochelate를 DMF에 녹여 NIPS (비용매 유도 상전이) 방법으로 제조하였다. Fe(II) clathrochelate의 첨가는 표면의 기공 밀도의 향상, 평균기공 크기의 증가 및 유량 증가에 영향을 주었으며 상대적으로 비대칭 구조를 가지는 성능이 향상된 멤브레인을 얻을 수 있었다.

• 한국산업보건학회지
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• 제16권2호
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• pp.183-192
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• 2006

Predicting energy expenditure (EE) is important to prevent work-related musculoskeletal disorders (WMSDs). The problem to predict EE is that the standard of EE is based on western data. The authors checked average EE by job categories to provide basic data for suggesting proper work intensity for Korean workers. This study was conducted from 2003 to 2005. Study subjects were recruited from 4 car parts assembly plant, 2 car assembly plant, 2 Heavy machine manufacturing plant and 2 shipyards. Total study subjects were 515 male workers. To estimate VO2max, sub-maximal test was conducted to measure VO275%max by bicycle ergometer (Combi Co, Aerobike 75XL II). Heartbeats were recorded with heartbeat recorder (Polar Electro Co, Finland, S810) during work. EE of work was calculated by recorded heartbeat and individual regression equation which was derived from sub-maximal test. Subjects were classified into 4 industry and 8 work posture, 23 job task categories. Mean EEs (S.D.) according to industry classification (kcal/min) were 4.9 (0.7), 4.8 (0.7), 4.9 (0.7), 5.0 (0.9), and 4.0 (0.5) for Car Part manufacture, Car Assembly, Ship Building, Heavy Machinery Manufacture, and Hospital Office, respectively. The results suggest that Korean male workers of exceeding to the NIOSH criteria will be needed to plan for job rescheduling to maintain $worker^{\circ}$Øs health. Further study to establish Korean work intensity standard would be needed.

• 한국수정란이식학회지
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• 제9권2호
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• pp.153-160
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• 1994

This study evaluated the influence of cell stage of donor nucleus on nuclear injection, electrofusion and in vitro development in the rabbit to improve the efficiency of nuclear transplantation in the rabbit. The embryos of 8-, 16- and 32-cell stage were collected from the mated does by flushing viducts with Dulbecco's phosphate buffered saline(D-PBS) containing 10% fetal calf serum(FGS) at 44, 54 and 60 hours after hCG injection. The blastorneres separated from these embryos were used as donor nucleus. The ovulated oocytes collected at 14 hours after hCG injection were used as recipient cytoplasm following removing the nucleus and the first polar body. The separated blastomeres were injected into the enucleated oocytes by micromanipulation and were electrofused in 0.28 M mannitol solution at 1.5 kV /cm, 60 $\mu$sec for three times. The fused oocytes were cocultured with a monolayer of rabbit oviductal epithelial cells in M-199 solution containing 10% FGS for 72~120 hours at 39$^{\circ}C$ in a 5% $CO_2$ incubator. The cultured nuclear transplant embryos were stained with Hoechst 33342 solution and the number of cells were counted by fluorescence microscopy. The successful injection rate of 8-, 16- and 32-cell-stageblastomeres into enucleated oocytes was 86.7, 91.0 and 93.9%, respectively. The electrofusion rate of 8-, 16- and 32-cell-stage blastomeres with enucleated oocytes was 93.3,89.3 and 79.0%, respectively. Development of blastomeres to blastocyst was similar with 8-,16- and 32-cell-stage donor nuclei(26.2, 25.8 and 26.6%, respectively, P<0.05). The mean number of cell cycle per day during in vitro culture in nuclear transplant embryos which received 8-, 16- and 32-cell- stage nuclei was 1.87, 1.81 and 1.43, respectively.

• 한국약용작물학회지
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• 제24권3호
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• pp.237-245
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• 2016

Background: Cyanazine is used as a pre-emergent herbicide once during the growing season to control weeds of many upland crops worldwide. This study aimed to establish a method to determined cyanazine residue levels in major medicinal crops by using high performance liquid chromatography-UV detection/mass spectometry (HPLC-UVD/MS). Methods and Results: Cyanazine residue was extracted with acetone from the raw products of four representative medicinal plants - Scutellaria baicalensis, Paeonia lactiflora, Platycodon grandiflorum and Angelica gigas. The extract was diluted with a large volume of saline water and directly partitioned into dichloromethane to remove polar co-extractives in the aqueous phase. It was then purifined using optimized Florisil column chromatography. HPLC analysis conducted using an octadecylsilyl column allowed the successful separation of cyanazine from co-extractives of the samples, and the amount was sensitively quantified by ultraviolet absorption at 225 nm with no interference. The accuracy and precision of the proposed method were validated by conducting recovery experiments on each medicinal crop sample fortified with cyanazine at two concentration levels per crop in triplicate. Conclusions: The mean recoveries ranged from 91.2% to 105.3% for the four representative medicinal crops. The coefficients of variation were less than 10%, irrespective of the sample types and fortification levels. The limit of quantification of cyanazine was 0.02 mg/kg as verified by the recovery experiment. A confirmatory method was performed by liquid chromatography/MS using selected-ion monitoring technique to clearly identify the suspected residue.

• 멤브레인
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• 제24권6호
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• pp.472-483
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• 2014

본 연구는 거대고리 금속 이온 착화합물과 유도체를 이용하여 미세 다공성 구조를 가지는 분리막의 제조에 관한 것이다. 고분자와 금속이온 리간드 착물 시스템을 이용함으로써 기존의 방법들에 비해 상 전이 과정을 보다 정교하게 제어할 수 있었다. 금속염, cyclohexanedione dioxime, hydroxyphenylboronic acid와의 축합 반응을 통하여 금속 clathrochelate 착물을 얻을 수 있었다. PES, PVP, BE와 금속 clathrochelate 착물을 DMF에 녹인 후 비용매 유도 상 전이법을 통하여 유무기 혼성고분자막을 제조하였다. 제조된 분리막의 구조는 FE-SEM과 microflow permporometer로 조사하였다. p-Hydroxyphenyl group을 가지는 Fe(II) clathrochelate 착물의 첨가는 분리막의 구조에 있어 기공 크기 분산도를 좁혀주고, 표면의 기공 밀도를 높여 주었으며 최대 기공 크기를 감소시킴을 볼 수 있었다.

• Ocean and Polar Research
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• 제27권4호
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• pp.381-395
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• 2005

The spatial distributions of macrobenthic communities in Masan Bay were investigated during summer and winter, 2004. A total of 104 species were sampled with mean density of $448ind./m^2$ and biomass of $77.1g/m^2$ in winter. In summer, a total of 107 species occurred with $485ind./m^2$ and a biomass of $94.5g/m^2$. The most dominant species in winter were Paraprionospio pinnata (24.2%) among polychaetous worms and Theora fragilis (14.1%) among molluscs, but they were replaced in summer by Prionospio chirrifera (20.4%) and Lumbrineris longifolia (14.5%). The difference in species composition and abundance of benthic communities between the two seasons was due to the hypoxia in the bottom layer of the inner bay during summer, which defaunated the macrofauna of the sediments. In the winter when DO concentration increased to normoxia, the pelagic larvae of benthic fauna settled in the soft sediments, but there was a spatial gradient in values of total biomass, density, and H' and benthic pollution index (BPI): higher values were found toward the mouth of the bay. The multivariate analyses like the cluster analysis and MDS ordination showed that Masan Bay could be divided into two or four stational groups in winter and summer whether the hypoxia occurred or not. Group I consisted of sites at the inner bay and central area and Group II, sites at the bay mouth. In summer the inner bay area could be further divided into the shallow impoverished area and the deeper abiotic one.

• Ocean and Polar Research
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• 제42권1호
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• pp.21-31
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• 2020

Shorebirds migrating along the East Asian-Australasian Flyway (EAAF) have been drastically decreasing due to continuous area loss and quality degradation of intertidal mudflats in the Yellow Sea. Evaluating the current habitat quality by means of habitat carrying capacity estimation could be effective in predicting the magnitude of impacts caused by habitat loss and provide better understanding to improve management strategies. In this study, we estimated the total biomass of Macrophthalmus japonicus, a main prey item of curlews in the Korea peninsular as habitat carrying capacity of the southern intertidal mudflat of Ganghwa Island, one of the key stopover sites for curlews in the EAAF. The result of the estimation took into account spatial differences of prey biomass and the available foraging time by tide patterns. Accordingly, it was found that curlew populations account for 30.26% of the habitat carrying capacity. When we calculated the mean biomass of the area and extrapolated it to the whole area to calculate the total biomass, it was found that the curlews have consumed 10.92% of the total biomass. The results show that the habitat carrying capacity of the southern intertidal mudflat of Ganghwa Island has decreased by 7.8% compared to a study conducted twenty years ago employing the same method. This study shows that there can be considerable differences in the results of habitat carrying capacity estimation between different methods, indicating that various environmental factors that affect the estimation results of habitat carrying capacity must be considered to achieve a more precise analysis and assessment.