• Korean Journal of Environmental Biology
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• v.41 no.2
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• pp.101-108
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• 2023

Recently, in relation to climate change, many studies have been conducted to predict the potential habitat area and distribution range of tilapia and the suitability of habitat for each species. Most tilapia are tropical fish that cannot survive at water temperatures below 10 to 12℃, although some tilapia can survive at 6 to 8℃. This study predicted habitable areas and the possibility of spreading of habitat ranges of tilapia (Oreochromis niloticus and Oreochromis aureus) known to inhabit domestic streams. Due to climate change, it was found that habitats in the Geum River, Mangyeong River, Dongjin River, Seomjin River, Taehwa River, Hyeongsan River, and the flowing in East Sea were possible by 2050. In addition, it was confirmed that tilapia could inhabit the preferred lentic ecosystem such as Tamjin Lake, Naju Lake, Juam Lake, Sangsa Lake, Jinyang Lake, Junam Reservoir, and Hoedong Reservoir. In particular, in the case of tilapia, which lives in tributaries of the Geumho River, Dalseo Stream, and the Nakdong River, its range of habitat is expected to expand to the middle and lower of the Nakdong River system. Therefore, it is judged that it is necessary to prepare physical and institutional management measures to prevent the spread of the local population where tilapia currently inhabits and to prevent introduction to new habitats.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.123-139
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• 1985

The present survey was undertaken to observe the geographical distibution of matacercaria among the sweetfish, Plecoglossus altivelis, the most important second intermediate host of Metagonimus yokegawai, which were collected during the period from 1983 to 1984 in south-eastern coastal areas of Korea. The results obtained were summarized as follow: 1. A total of 668 sweetfish collected from 70 chins (=streams) in the above coastal arcus was examined for the metacercariae, and 432 (64.7%) among them were infected with metacercariae of M. yokogawai. The mean number of metacercariae in a fish was in the range from 0 to 29,604 and the mean number of the metacercariae in a fish was 640.3. 2. It was observed that the mean infection rate showed 46.45 in Gangweon-Do (=province) . The infection rates varied from stream to stress showing 100% in Namdae stream(Gangnun-city) , Obsib stream (Samchok-gun) and Dongmak, 95.0% in Hosan stream, 90.0% in Gungchin stream, and Namdae stream (Yangyang-fp) ,80.0% in Hwasang stream,50.0% in Daebong stream,45.0% in Yonghwa stream, 30.0% in sangchsn stream and Sachsn stream, 20.0% in Munam stream and Okgyoe stream, 15.0% in Imweon stream, 10.0% in Namchsn stream. And no metacercarial infections in their fish host were found in the areas of Mulchi stream, Sangun stream, Gosamun stream, Jonchon stream and Gagok stream. 3. It was observed that the mean infection rate showed 50.9% in Kyangsangbuk-Do (=province). The infection rates also varied from stream to stream showing 100% in Songchon stream, Osib stream (Yongdok-gun) and Daejong stream,60.0% in Pyanghae stream and Gunmu stream,50.0% in Buhwung stream and stream, 25.0% in Nagok stream, 20.0% in Oangbi stream, 10.0% in Namhodong stream. And no metacercarial infections in their fish host were found in the areas of Namdae stream (Uljinup) and Chaksan stream. 4. It was observed that the mean infection rate showed 67.6% in Kyangsangnam-Do(=province). The infection rates varied from stream to stream showing 100% in Taehwa river, Hwiya river, Inchfn stream, Miryang river, Nam river, Hwagae stream, Koha stream, Sosang stream, and Tongchon stream,90.9% in Yancho stream,90.0% in Hoihwa stream,80.0% in Chindong stream, 66. YoA in Chingyo stream, 40.0% in Hoyam river. And no metacercarial infections in their fish host were found in the areas of Chinjon stream, Sanchan stream and Jukch6n stream. 5. It was observed that the mean infection rate showed 94.6"A in 0h511anam-Do(=province). The infection rates varied from stream to stream showing 100% in DongchEn stream, Isachon stream, Somjin river(GoksEng-gun) , Ssmjin river(Kurye-gun) , S6si stream, Gokchsn stream, Kohung stream, Kwansan stream, Youi stream, stream, Unj6n stream and Apnae stream, 92.3% in Tamjin river, 90.9% in Okkok stream, 84.6% in Songgen stream. And no metacercarial infections in their fish host were found in the area of Ypmgpl stream. 6. On the other hand, the infection rate showed 100% in Inchsn river of Chollabuk Do (=province) (=province) and Kangsn stream of Cheju-Do(=province) .

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.8-9
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• 2017

Soybean yield has been low and unstable in Japan and other areas in East Asia, despite long history of cultivation. This is contrasting with consistent increase of yield in North and South America. This presentation tries to describe perspective of breaking stagnation of soybean yield in East Asia, considering the factors of the different yields between regions. Large amount of rainfall with occasional dry-spell in the summer is a nature of monsoon climate and as frequently stated excess water is the factor of low and unstable soybean yield. For example, there exists a great deal of field-to-field variation in yield of 'Tanbaguro' soybean, which is reputed for high market value and thus cultivated intensively and this results in low average yield. According to our field survey, a major portion of yield variation occurs in early growth period. Soybean production on drained paddy fields is also vulnerable to drought stress after flowering. An analysis at the above study site demonstrated a substantial field-to-field variation of canopy transpiration activity in the mid-summer, but the variation of pod-set was not as large as that of early growth. As frequently mentioned by the contest winners of good practice farming, avoidance of excess water problem in the early growth period is of greatest importance. A series of technological development took place in Japan in crop management for stable crop establishment and growth, that includes seed-bed preparation with ridge and/or chisel ploughing, adjustment of seed moisture content, seed treatment with mancozeb+metalaxyl and the water table control system, FOEAS. A unique success is seen in the tidal swamp area in South Sumatra with the Saturated Soil Culture (SSC), which is for managing acidity problem of pyrite soils. In 2016, an average yield of $2.4tha^{-1}$ was recorded for a 450 ha area with SSC (Ghulamahdi 2017, personal communication). This is a sort of raised bed culture and thus the moisture condition is kept markedly stable during growth period. For genetic control, too, many attempts are on-going for better emergence and plant growth after emergence under excess water. There seems to exist two aspects of excess water resistance, one related to phytophthora resistance and the other with better growth under excess water. The improvement for the latter is particularly challenging and genomic approach is expected to be effectively utilized. The crop model simulation would estimate/evaluate the impact of environmental and genetic factors. But comprehensive crop models for soybean are mainly for cultivations on upland fields and crop response to excess water is not fully accounted for. A soybean model for production on drained paddy fields under monsoon climate is demanded to coordinate technological development under changing climate. We recently recognized that the yield potential of recent US cultivars is greater than that of Japanese cultivars and this also may be responsible for different yield trends. Cultivar comparisons proved that higher yields are associated with greater biomass production specifically during early seed filling, in which high and well sustained activity of leaf gas exchange is related. In fact, the leaf stomatal conductance is considered to have been improved during last a couple of decades in the USA through selections for high yield in several crop species. It is suspected that priority to product quality of soybean as food crop, especially large seed size in Japan, did not allow efficient improvement of productivity. We also recently found a substantial variation of yielding performance under an environment of Indonesia among divergent cultivars from tropical and temperate regions through in a part biomass productivity. Gas exchange activity again seems to be involved. Unlike in North America where transpiration adjustment is considered necessary to avoid terminal drought, under the monsoon climate with wet summer plants with higher activity of gas exchange than current level might be advantageous. In order to explore higher or better-adjusted canopy function, the methodological development is demanded for canopy-level evaluation of transpiration activity. The stagnation of soybean yield would be broken through controlling variable water environment and breeding efforts to improve the quality-oriented cultivars for stable and high yield.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.1-11
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• 2015

Salinity affects sound speed in the low salinity environment, in the seas where freshwater from large rivers and flows into the marginal sea area near the Yangtze River and the Niger River. In this paper, SSC (Surface Sound Channel) formed by low salinity water was investigated in the East China Sea and the Gulf of Guinea of rainy season. The data from KODC (Korea Oceanographic Data Center) in the East China Sea and from ARGO (Array for Real-time Geostrophic Oceanography) in the Gulf of Guinea of the tropical area were used for analysis. SSC haline channel was formed 14 times among 32 SSC occurrences when the 90 data from 9 points were analyzed during a decade (2000 ~ 2009) in the East China Sea. In the Gulf of Guinea, haline channel was formed 18 times among 20 SSC occurrences during 3 years (2006 ~ 2009). When the sound speed gradient was analyzed from temperature-salinity gradient diagram, the gradients of both salinity and temperature affect SSC formation in the East China Sea. In contrast, the salinity gradient mostly affects SSC formation due to the least change of temperature in the well-developed mixed layer in the Gulf of Guinea. Their acoustic characteristics show that channel depth is 6.5 m, critical angle is $1.5^{\circ}$ and difference of transmission loss between surface and thermocline is 11.5 dB in the East China Sea, while channel depth is 18 ~ 24 m, critical angle is $4.0{\sim}5.4^{\circ}$ and difference of transmission loss is 21.5 ~ 27.9 dB in the Gulf of Guinea. These results are expected to be used as a basic understanding of the acoustic transmission changes due to low salinity water at the estuaries and the ocean with heavy precipitation.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.3
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• pp.48-57
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• 2018

In this study, we conducted an analysis on the actual field materials and the ancient text of January 2017. First, Yuyin ShanFang is one of the famous garden in the Lingnan Region, and its total area is $1598m^2$. Wobin called the name 'Yuyin(餘蔭)' meaning the virtues of his ancestors. Second, if we analyze the poem written by Wobin, we can classify it as a phrase expressing the world beyond the future, a poem expressing the ideas of family and romantic ideas. Third, the space spread to the south around the shrine building in the middle of the site was largely a residential space, according to the analysis of the site's layout and spatial composition. Fourth, the spatial component of the hydronic acid is analyzed. The pavilion area is the Hanchwi-Pavilion, which is designated in the Wongrim, and Gyesang-Pavilion, which is a unique range that describes the peak of the garden. Fifth, Yuyin ShanFang has five ponds that are very diverse in shape. It is characteristic of us to stand on a technical boundary. Sixth, Seokgasan was referred to as Gyeongbansan, which was named after The builder Wobin and his descendants who passed it. Seventh, Hwachang is characterized by a wooden bull window and a compound glass. Eighth, the alumni style is not as diverse as the alumni style of the Suzhou traditional garden, but it features various forms and colorful pictures on the front of the alumni. Ninth, the one-piece sculptures of the interior of a building are expressed themes such as Gilsang, Sukjeong, Daoism, Palseom, and others. Finally, Trees planted in Yuyin ShanFang are mostly tropical plants, and some of them have symbolic meaning. Because the weather here is good for growing fruit, so planted a lot of fruit trees.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.371-384
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• 1982

Highly cold tolerant varieties are requested not only at high latitute cool area but also tropical high elevated areas, and the required tolerance is different from location to location. IRRI identified 6 different types of cold tolerance required in the world for breeding purpose; a) Hokkaido type, b) Suweon type, c) Taipei 1st season type, d) Taipei 2nd season type, e) Tropical alpine type and, f) Bangladesh type. The cold tolerance requested in Korea is more eargent in Tongil group cultivars and their required tolerance is the one such as the physiological activities at low temperature are as active as in Japonica group cultivars at least during young seedling stage and reproduction stage. With conventional Japonica cultivars, such cold tolerant characters are requested as short growth duration but stable basic vegetative growth, less sensitive to high temperature and less prolonged growth duration at low temperature. The methods screening for cold tolerance were developed rapidly after the Tongil cultivar was reliesed. The facilities of screening for cold tolerance, such as, low temperature incubator, cold water tank, growth cabinet, phytotron, cold water nursery in Chuncheon, breeding nursery located in Jinbu, Unbong and Youngduk, are well established. Foreign facilities such as, cold water tank with the rapid generation advancement facilities, cold nurseries located in Banaue, Kathmandu and Kashimir may be available for the screening of some limitted breeding materials. For the reference, screening methods applied at different growth stages in Japan are introduced. The component characters of cold tolerance are not well identified, but the varietal differences in a) germinability, b) young seedling growth, c) rooting, d) tillering, e) discolation, f) nutrition uptake, g) photosynthesis rate, h) delay in heading, i) pollen sterility, and j) grain fertility at low temperature are reported to be distinguishable. Relationships among those traits are not consistent. Reported studies on the inheritance of cold tolerance are summarized. Four or more genes are controlling low temperature germinability, one or several genes are controlling seedling tolerance, and four or more genes are responsible for the pollen fertility of the rice treated with cold air or grown in the cold water nursery. But most of those data indicate that the results may come out in different way if those were tested at different temperature. Many cold tolerant parents among Japonicas, Indicas and Javanicas were identified as the results of the improvement of cold tolerance screening techniques and IRTP efforts and they are ready to be utilized. Considering a) diversification of germ plasm, b) integration of resistances to diseases and insects, c) identification of adaptability of recommending cultivars and, d) systematic control of recommending cultivars, breeding strategies for short term and long term are suggested. For short term, efforts will be concentrated mainly to the conventional cultivar group. Domestic cultivars will be used as foundation stock and ecologically different foreign introductions such as from Hokkaido, China or from Taiwan, will be used as cross parents for the adjustment of growth durations and synthsize the prototype of tolerances. While at the other side, extreme early waxy Japonicas will be crossed with the Indica parents which are identified for their resistances to the diseases and insects. Through the back corsses to waxy Japonicas, those Indica resistances will be transfered to the Japonicas and these will be utilized to the crosses for the improvement of resistances of prototype. For the long term, efforts will be payed to synthsize all the available tolerances identified any from Japonicas, Indicas and Javanicas to diversify the germ plasm. The tolerant cultivars newly synthsized, should be stable and affected minimum. to the low temperature at all the growing stages. The resistances to the diseases and insects should be integrated also. The rapid generation advancement, pollen culture and international cooperations were emphasized to maximize the breeding efficiency.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.103-110
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• 1993

This study was made to evaluate the chemical properties of 481 farmers' orchard fields in An-Seong area. And the reasonable ferilizer rates were recommended utilizing the result of soil analysis. The results are summarized as follows : 1. As the soil fertility status of collected soil samples were evaluated on the basis of temporary optimal range for each soil chemical properties, 12.7 to 49.6% of the total 481 farmers' fields were range for soil improvement. 2. The contents of chemical component have a tendancy to decrease with depth gradually from surface to subsoil. 3. According to the relationship between the contents of soil component in subsoil and those in surface soil, the fertility condition of subsoil could be estimated on the basis of analysis data of surface soil. 4. The multiple regression equation for pear yield prediction to the organic matter and exchangable calcium contents in the soil were obtained. 5. Referring the average value, distribution ratio compared to the optimum level for each soil chemical properties and standard fertilizer rate, the soil fertility status could be categorized as "High" "Medium" and "Low". For each category, the recommended amounts for NPK and organic matter application were established. 6. The recommended rates through soul fertility diagnosis were less than farmer's dosage in the range 7.1~7.7 kg/10a for N, 0.8~11.5 kg/10a for $P_2O_5$, 7.1~19.9 kg/10a for $K_2O$ and 90~116 kg/10a for lime.

• 한국해양학회지
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• v.30 no.6
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• pp.550-564
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• 1995

The temporal and spatial characteristics of wind fields over the neighbouring seas of the Korean peninsula are investigated using 10-years daily wind data during 1978${\sim}$1987 which have been spatially smoothed and low-pass filtered. Long term annual and monthly means are examined for synoptic patterns and spectral analyses are made for temporal variability and spatial coherence. Spatial patterns of the annual mean wind stress and curl have a strong resemblance with those of monthly means during the winter season. Two outstanding periodicities are observed at 1 and 2 cycles per year. The synoptic winds over the study area are highly coherent at both the annual and semi-annual periodicities. However, each basin has its own characteristic spatial pattern. For instance, the prevailing wind during the winter season is northerIy over the northern East Sea (ES), Yellow Sea (YS), and northern East China Sea (ECS), while it is northwesterly over the southern ES and northesterly over the northern ES and southern ECS. At the same time, the wind stress curl is positive over the northern ES and southern ECS, while it is negative over the southern ES, YS and northern ECS. On the other hand, the wind field during the summer season, with its strength being much reduced, is completely different from that during the winter season, and frequent passage of tropical storms provokes large temporal variability over ECS. One remarkable point is that the annual cycle, dominated by the Siberian High, tends to propagate from northeast to southwest, i.e., from northern 25 toward southern ES, YS and ECS, while the semi-annual cycle propagates in the opposite direction, from southwest to northeast. The semi-annual periodicity may reflect development of extratropical cyclones in spring and fall which frequently cross the Korean peninsula. In higher frequencies, there are no dominant periodicities, but local winds over YS and ES are highly correlated for frequencies larger than 0.1 cycles per day and phase difference increases linearly with frequency. This linear increase of phase corresponds to phase speed of 550 and 730 km/d at 0.1 and 0.3 cpd, respectively, The phase speed is apparently coincident with moving speed of extratropical cyclones across the Korean peninsula in the west-east direction.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.87-94
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• 1985

The seasonal variations of the rate and intensity of metacercarial infection of C. sinensis in P. parva were observed. The fish were collected at Sun-Am River which located in Kim-Hae City, Kyong-Sang Nam Do (=Province), Korea, from March 1983, to February 1984 every month. A total of 788 fish was examined. The number of metacercariae in each fish was individually counted after the individual digestion by artificial gastric juice. The results were as follows: 1. During one year, 513 (65.1%) out of 788 fish were infected with metacercariae. In May, June, July and September, the infection rates ranged from 82.0% to 98.6% whereas the rates was relatively low in March, April, November and February ranging from 11.4% to 64.7%. 2. The intensity of infection was similar with those of infection rates. The mean intensity per infected fish was 103.0 and standard deviation was 118.9 throughout one year. The highest mean intensity was in June (294.8) and the lowest in November (11.1). 3. The observed frequency of fish with certain intensities of metacercariae were fitted to theoretical equations derived from negative binomial distribution in March, April, November and February (p>0.05). Meanwhile, the equation of lognormal distribution were fitted with the observed frequencies in May, June, July and September (p>0.05, p>O. 75). The variance/mean ratio varied by month. The value was the highest in July (814.3) and the lowest in November (158.8). Unlike our hypothesis, the metacercarial density of Clonorchis sinensis in its the most favorable fish host, Pseudorasbora parva showed considerable seasonal variations in the hyperendemic area. The possible factors were discussed.

• Journal of Korean Society of Forest Science
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• v.99 no.1
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• pp.9-15
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• 2010

This study was conducted to develop a stand growth model and a stand yield table for Eucalyptus pellita and Acacia mangium plantations in Kalimantan, Indonesia. To develop a stand growth model, Weibull robability density function, a diameter class model, was applied in this study. In the development of stand growth model by site index and stand age, a hierarchy is generally required - estimation, recovery and prediction of the diameter class model. A number of grow equations were also involved in each process to estimate diameter, height, basal area, minimum or maximum diameter. To examine whether the grow equations are adequate for Eucalyptus pellita or Acacia mangium plantations, a fitness index was analyzed for each equation. The results showed that fitness indices were ranged from 65 to 89% for Eucalyptus pellita plantations and from 72 to 95% for Acacia mangium plantations. As being highly adequate for the plantations, a stand yield table was developed based on the resulted growth model, and applied to estimate the stand growth with midium site index for 10-year period. The highest annual stand growth of Eucalyptus pellita plantations was estimated to be 21.25 $m^3$/ha, while that of Acacia mangium plantations was 27.5 $m^3$/ha. In terms of annual stand growth, Acacia mangium plantations appeared to be more beneficial than Eucalyptus pellita plantations. Also, to estimate commercial timber volume available from the plantations, an assumption that a log would be cut by 2.7 m in length and the rest of the log would be cut by 1.5m was involved. The commercial timber volume available from Eucalyptus pellita plantations was 68.0 $m^3$/ha, 33% from the total stand volume, 203.2 $m^3$/ha. Also 96.7 $m^3$/ha of commercial timbers were available from Acacia mangium plantations, which was 42% from the 232.9 $m^3$/ha in total. Presenting a good information about the stand growth in Eucalyptus pellita and Acacia mangium plantations, this study might be useful for whom proceeds or considers an abroad plantation for merchantable timber production or carbon credit in tropical regions.