• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.24 no.3
• /
• pp.203-213
• /
• 1991

Zooplankton samples were collected vertically from different layers with a closing net at 14 stations in the middle East Sea of Korea in February, August and September to study distribution of biological indicators for analysis of water masses. Horizontal and vertical distributions of important species of copepods and chaetognathas known as indicator species were closely related to distributions of different water masses and oceanic fronts. Pleuromamma gracilis, Calanus tenuicornis, Sagitta enflata and Sagitta minima were found to be reliable indicator species to determine warm water mass with warm core, and Calanus cristatus, Calanus tonsus and Sagitta elegans could be used as cold water species for evaluating the movement of cold current from North Korea, and Gaetanus armiger was deep sea water species. Therefore, it was found that North Korean Cold Current down to the south along the coast appeared to be significant in the surface around Chumunjin area, and from here towards the south the cold water containing S. elegans submerged under warm water with S. enflata which were about $2{\~}4^{\circ}C$ higher than that of the vicinity and reappeared near Chukpeon area in surface layer. In the layer between loom and 300m depths, distribution of Pleuromamma gracilis and Sagitta bedoti indicated that warm water mass and front zone influenced by the different water systems were formed in northwestern area off Ulreung-do. In $300{\~}500m$ layer, the proper cold water could be estimated to be present in the northwestern area off Ulreung-do throughout the survey period by the high abundance of Gaetanus armiger. In August, distributions of S. bedoti, S. enflata and S. minima were valuable index to find oceanic fronts and warm core.

• Journal of Korean Society of Forest Science
• /
• v.73 no.1
• /
• pp.1-8
• /
• 1986

Relationship between distribution of tree species and salt concentration in soil was studied in order to understand the salt tolerance of tree species in the middle part of Korean east coast and its results were as follows; 1) The tree species in the area mostly consist of Pinus thunbergii, Pinus densiflora, Rosa rugosa, Lespedeza bicolor, Amorpha fruticosa, Quercus dentata, Rhododendron mucronulatum, Rohinia pseudoacacia and others. 2) Pinus thunbergii was dominant species and Rosa rugosa gradually disappeared at the distance from the beach line to 200 meters toward inland. Pinus thunbergii tended to disappear gradually and Pinus densiflora was dominant at the distance from 200 meters to 300 meters inland. 3) Pinus thunbergii was dominant below 50 meters in altitude while Pinus densiflora was dominant above 50 meters. 4) NaCl content tended to decrease as proceeding to inland, higher altitude and to shallow depth of soil. 5) Change in pH in terms of distance toward inland and altitude was not significant, but change in pH along soil depth was conspicuously decreasing from pH 7.0 of top soil to pH 6.5 50cm below. 6) Pinus thunbergii was densely distributed to the area where soil NaCl content was higher than 100 vpm, while Pinus densiflora dominated the area of less than 100 vpm. Rosa rugosa was shown to dominate the area of over 100 vpm soil NaCl content. 7) NaCl content in tree tended to decrease, as proceeding to inland, rapidly within 150 meters distance from the beach line and gradually at further distances. NaCl content in leaf was about 600 ppm, branch 350ppm and root 250 ppm.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.36 no.5
• /
• pp.407-428
• /
• 1991

The eastern coastal area having variability of climate is located within Taebaek mountain range and the east coast of Korea. It is therefore ease to cause the wind damages in paddy field during rice growing season. The wind damages to rice plant in this area were mainly caused by the Fohn wind (dry and hot wind) blowing over the Taebaek mountain range and the cold humid wind from the coast. The dry wind cause such as the white head, broken leaves, cut-leaves, dried leaves, shattering of grain, glume discolouration and lodging, On the other hand the cold humid wind derived from Ootsuku air mass in summer cause such symptom as the poor rice growth, degeneration of rachis brenches and poor ripening. To minimize the wind damages and utilize as a preparatory data for wind injury of rice in future, several experiments such as the selection of wind resistant variety to wind damage, determination of optimum transplanting date, improvement of fertilizer application methods, improvement of soils and effect of wind break net were carried out for 8 years from 1982 to 1989 in the eastern coastal area. The results obtained are summarized as follows. 1. According to available statisical data from Korean meteorological services (1954-1989) it is apperent that cold humid winds frequently cause damage to rice fields from August 10th to September 10th, it is therefore advisable to plan rice cultivation in such a way that the heading date should not be later than August 10th. 2. During the rice production season, two winds cause severe damage to the rice fields in eastern coastal area of Korea. One is the Fohn winds blowing over the Taebaek mountain range and the other is the cold humid wind form the coast. The frequency of occurrence of each wind was 25%. 3. To avoid damage caused by typhoon winds three different varieties of rice were planted at various areas. 4. In the eastern coastal area of Korea, the optimum ripening temperature for rice was about 22.2$^{\circ}C$ and the optimum heading date wad August 10th. The optimum transplanting time for the earily maturity variety was June 10th., medium maturity variety was May 20th and that of late maturity was May 10th by means of growing days degree (GDD) from transplanting date to heading date. 5.38% of this coastal area is sandy loamy soil while 28% is high humus soil. These soil types are very poor for rice cultivation. In this coastal area, the water table is high, the drainage is poor and the water temperature is low. The low water temperature makes it difficult for urea to dissolve, as a result rice growth was delayed, and the rice plant became sterile. But over application of urea resulted in blast disease in rice plants. It is therefore advise that Ammonium sulphate is used in this area instead of urea. 6. The low temperature of the soil inhibits activities of microorganism for phosphorus utilization so the rice plant could not easily absorb the phosphorus in the soil. Therefore phosphorus should be applied in splits from transplanting to panicle initiation rather than based application. 7. Wind damage was severe in the sandy loamy soil as compared to clay soils. With the application of silicate. compost and soil from mointain area. the sand loamy soil was improved for rice grain colour and ripening. 8. The use of wind break nets created a mocro-climate such as increased air. soil and water temperature as well as the reduction of wind velocity by 30%. This hastened rice growth, reduced white head and glume discolouration. improved rice quality and increased yield. 9. Two meter high wind break net was used around the rice experimental fields and the top of it. The material was polyethylene sheets. The optimum spacing was 0.5Cm x 0.5Cm. and that of setting up the wind break net was before panicle initiation. With this set up, the field was avoided off th cold humid wind and the Fohn. The yield in the treatment was 20% higher than the control. 10. After typhoon, paddy field was irrigated deeply and water was sprayed to reduce white head, glume discolouration, so rice yield was increased because of increasing ripening ratio and 1, 000 grain weight.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.3
• /
• pp.147-153
• /
• 2013

There exist various types of the WEC (Wave Energy Converter), and among them, the point absorber is the most popularly investigated type. However, it is difficult to find examples of systematically measured data analysis for the design of the point absorber type of power buoy in the world. The study investigates the wave load acting on the point absorber type resonance power buoy wave energy extraction system proposed by Kweon et al. (2010). This study analyzes the time series spectra with respect to the three-year wave data (2002.05.01~2005.03.29) measured using the pressure type wave gage at the seaside of north breakwater of Hupo harbor located in the east coast of the Korean peninsula. From the analysis results, it could be deduced that monthly wave period and wave height variations were apparent and that monthly wave powers were unevenly distributed annually. The average wave steepness of the usual wave was 0.01, lower than that of the wind wave range of 0.02-0.04. The mode of the average wave period has the value of 5.31 sec, while mode of the wave height of the applicable period has the value of 0.29 m. The occurrence probability of the peak period is a bi-modal type, with a mode value between 4.47 sec and 6.78 sec. The design wave period can be selected from the above four values of 0.01, 5.31, 4.47, 6.78. About 95% of measured wave heights are below 1 m. Through this study, it was found that a resonance power buoy system is necessary in coastal areas with low wave energy and that the optimal design for overcoming the uneven monthly distribution of wave power is a major task in the development of a WEF (Wave Energy Farm). Finding it impossible to express the average spectrum of the usual wave in terms of the standard spectrum equation, this study proposes a new spectrum equation with three parameters, with which basic data for the prediction of the power production using wave power buoy and the fatigue analysis of the system can be given.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.17 no.4
• /
• pp.262-269
• /
• 2012

We investigated the concentration levels and evaluated the distributions of 17 polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs), 12 dioxin-like polychlorinated biphenyls(DLPCBs) and 24 polybrominated diphenyl ethers (PBDEs) in sediment and organism from various culturing grounds in Korean coast. The levels of PCDD/Fs, DLPCBs, and PBDEs in sediment samples ranged from 0.03 to 2.9(Mean${\pm}$SD, $1.2{\pm}0.89$) pg $WHO_{2005}$-TEQ $g^{-1}$ dry weight(dw), ND(not detected) to 1.1($0.09{\pm}0.19$) pg $WHO_{2005}$-TEQ $g^{-1}$ dw, and ND to 16.6($2.96{\pm}3.53$) ng $g^{-1}$ dw, respectively. Also, the levels of PCDD/Fs, DLPCBs, and PBDEs in culturing organisms ranged from ND to 0.24($0.07{\pm}0.06$) pg $WHO_{2005}$-TEQ $g^{-1}$ wet weight(ww), ND to 0.11($0.04{\pm}0.04$) pg $WHO_{2005}$-TEQ $g^{-1}$ ww, and 0.05 to 0.29($0.13{\pm}0.06$) ng $g^{-1}$ ww, respectively. The levels of total dioxins(PCDD/Fs+DLPCBs) and PBDEs in sediments from East and South sea were four to seven times higher than those from West sea. PCDD/Fs had dominant contribution(mean, 94%) for TEQ concentration in sediment, whereas relatively higher contribution of DLPCBs(33%) were shown in culturing organism than sediment. BDE209 was a dominant congener in both matrix. The concentrations of PCDD/Fs, DLPCBs and PBDEs were in decreasing trends in Korea coasts compared to previous results.

• Journal of Preventive Medicine and Public Health
• /
• v.21 no.1 s.23
• /
• pp.183-194
• /
• 1988

This study was carried out to investigate for resistance of V. parahaemolyticus that isolated from patients of food poisoning and fish and shellfish, captured in east coast of Kyungpook province of Korea from 1985 to 1986. VP ATCC 17802 and NAG V. ATCC 6538 were used as control. In fish, shellfish and seaweed, the more temperature increased, the shorter survival time was. In case of sea-water, the more temperature rose up, the longer survival time was, particularly in $37^{\circ}C$ and $25^{\circ}C$, the strains had survived after 6 months. And in tapwater, it was sterilized in 150 mins. and survived for 11.5 days on maximum in ground water. In kimchi, at room temperature, germicidal time was shorter more than 6 times compared with that which had been kept in refrigerator. It survived for 57.1 days in milk, 49.2 mins. in yougurt. Strains had been surviving in frozen condition at $-70^{\circ}C$ even after 6 months, present study time. In resistance test in water bath at several degrees of temperature, all the strains were sterilized in 20 mins. with $60^{\circ}C$. In resistance test to driness, number of surviving strains dropped rapidly in 10-11%) water contents. In UV $2538{\AA}$, strains were sterilized in 20 mins. In resistance test to alcohol, strains had survived for 0.1-4 mins. in fermentative wine of below than 25% and distilled wine of over than 25% in alcohol concentration. The bactericidal concentration of disinfectant was 1% in phenol and 3% in cresol. In 0.1M acetic acid and 0.1M lactic acid, number of surviving colonies decreased rapidly but not in citric acid. The more NaCl concentration rose up, the lower decreasing rate of number of surviving colonies was. The strains had showed sensitive response to vancomycin, chloramphenicol, gentamicin, and resisted to carbenicillin, ampicillin and kanamycin. When one day culture strain was cultured till 25th day, resistant strains to tetracycline and cephalothin were changed to sensitive.

• Korean Journal of Soil Science and Fertilizer
• /
• v.51 no.1
• /
• pp.16-27
• /
• 2018

To predict the influence of volcano eruption on agriculture in South Korea we evaluated the dispersal ranges of the volcanic ashes toward the South Korea based on the possibilities of volcano eruption in Mt. Baekdu. The possibilities of volcano eruption in Mt. Baekdu have been still being intensified by the signals including magmatic unrest of the volcano and the frequency of volcanic earthquakes swarm, the horizontal displacement and vertical uplift around the Mt. Baekdu, the temperature rises of hot springs, high ratios of $N_2/O_2$ and $_3He/_4He$ in volcanic gases. The dispersal direction and ranges and the predicted amount of volcanic ash can be significantly influenced by Volcanic Explosivity Index (VEI) and the trend of seasonal wind. The prediction of volcanic ash dispersion by the model showed that the ash cloud extended to Ulleung Island and Japan within 9 hours and 24 hours by the northwestern monsoon wind in winter while the ash cloud extended to northern side by the south-east monsoon wind during June and September. However, the ash cloud may extent to Seoul and southwest coast within 9 hours and 15 hours by northern wind in winter, leading to severe ash deposits over the whole area of South Korea, although the thickness of the ash deposits generally decreases exponentially with increasing distance from a volcano. In case of VEI 7, the ash deposits of Daejeon and Gangneung are $1.31{\times}10^4g\;m^{-2}$ and $1.80{\times}10^5g\;m^{-2}$, respectively. In addition, ash particles may compact close together after they fall to the ground, resulting in increase of the bulk density that can alter the soil physical and chemical properties detrimental to agricultural practices and crop growth.

• Journal of the Korean earth science society
• /
• v.21 no.3
• /
• pp.230-249
• /
• 2000

Southeastern Korean Peninsula has undergone the polyphase deformations according to the changes of regional tectonic settings during the Cenozoic. Through analyses of more than 600 fault-slip data gathered in the study area, five tectonic events are revealed as the followings: (I) NW-SE transtension, (II) NW-SE transpression, (III) NE-SW pure or radial extension, (IV) NNE-SSW transpression, (V) NE or ENE-WSW transpression. Event I was induced by the pull-apart type extension of the East Sea during 24-16 Ma, which resulted in the NW-SE extension of the Tertiary Basins in SE Korea. Event II was resulted from the collision of SW Japan and Izu-Bonnin Arc (or Kuroshio Paleoland) on the Philippine Sea Plate at ${\sim}$ 15 Ma, which stopped the extension of the Tertiary Basins and originated the uplift of fault blocks in and around SE Korean Peninsula. It was continued until ${\sim}$ 10 Ma. Event III is interpreted as the post-tectonic event after the block-uplifts due to the event II, which indicates a temporal lull in activity of the Philippine Sea Plate since 10 Ma. Event IV was originated from the resumption in activity of the Philippine Sea Plate which was restarted to move toward north at ${\sim}$ 6 Ma. The event made the EW compressional structures behind SW Japan as well as in the Korea Straits, and thus the block-uplifts in SE Korea was resumed again. Lastly, event V was resulted from the gradual decrease in influence of the Philippine Sea Plate and the cooperative compression due to the subduction of the Pacific Sea Plate and the collision of the Indian Plate since 5-3.5 Ma, which generated the NS compressional structures in the offshore along the eastern coast of the Korean Peninsula and thrust up the fault-blocks toward west. This event is continuing so far, and thus is making the active faultings resulting in the present earthquakes of the Korean Peninsula.

• Economic and Environmental Geology
• /
• v.34 no.4
• /
• pp.375-383
• /
• 2001

We extracted sea surface heights(SSH) from the TopexJPoseidon(T/P) radar altimeter data to compare with fhe SSH estimated from in-situ lide gauges(T/G) at Ulleungdo, Pohang, and SockcholMucko sites. Selection criteria such as wet/dry troposphere, ionosphere, and ocean tide were used to estimate accurate SSH. For time series analysis, the one-hour interval tide gauge SSHs were resampled al lO-day interval of the satellite SSHs. The ocean tide model applied in the altimeter data processing showed periodic aliasings of 175.5 day, 87.8 day, 62J day, 58.5 day, 49.5 day and 46.0 day, and, hence, the ZOO-day filtering was applied to reduce these spectral noises. Wavenumber correlation analysis was also applied to extract common components between the two SSHs, resulting in enhancing the correlation coefficient(CC) dramatically. The original CCs between the satenite and tide gauge SSHs are 0.46. 0.26, and 0.]5, respectively. Ulleungdo shows the largest cc bec;luase the site is far from the coast resulting in the minimun error in the satellite observations. The CCs were then increased to 0.59, 030, and 0.30, respectively, after 200.day filtering, and to 0.69, 0.63. and 0.59 after removing inversely correlative components using wavenumber correlation analysis. The CCs were greatly increased by 87, 227, and 460% when the wavenumber correlation analysis was followed by 2oo-day filtering, resulting in the final CCs of 0.86, 0.85, 0.84, respectively. It was found that the best SSHs were estimated when the two methods were applied to the original data. The low-pass filtered TIP SSHs were found to be well correlated with the TIG SSHs from tide gauges, and the best correlation results were found when we applied both low-pass filtering and spectral correlation analysis to the original SSHs.

• Weed & Turfgrass Science
• /
• v.6 no.1
• /
• pp.11-20
• /
• 2017

Ninety species belonging to 28 families of weeds were identified in Korean rice fields. They were divided by eight provinces and 19 agro-climatic zones to be used as basic data of weed control. Looking at the regional weed occurrence, there were 52 species of 20 families in Gyeonggi, 37 species of 17 families in Gangwon, 41 species of 15 families in Chungbuk, 21 species of 12 families in Chungnam, 24 species of 13 families in Jeonbuk, 54 species of 21 families in Chonnam, 36 species of 20 families in Gyeongbuk, and 32 species of 16 families in Gyeongnam province, respectively. The most dominant family was Poaceae followed by Cyperaceae and Asteraceae. Mostly dominant species were Echinochloa spp., Monochoria vaginalis var. plantaginea, Scirpus juncoides var. hotarui, Eleocharis kuroguwai, and Sagittaria sagittifolia subsp. leucopetala with slight differences among the provinces. Although there were some differences in 18 climate zones from Taebaek sub-highlands to the southern part of the East Coast (except for the Taebaek Highland), the dominant species were Echinochloa spp., Monochoria vaginalis var. plantaginea and Scirpus juncoides var. hotarui. The most dominant family was Cyperaceae followed by Poaceae and Asteraceae. The differences of weed occurrence between provinces and agro-climatic zones were largely influenced by various weather conditions rather than the provinces. The changes in cultivation mode and herbicide use might influence as well.