• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.3
• /
• pp.274-294
• /
• 2007

The most reasonable method of counting the number of the estuaries in Korea may be counting the number of streams flowing into the sea. The number counting of the streams should be carried out based on the river classes (National River, Regional 1st Class River and Regional 2nd Class River) given by the River Act. The National River scale estuaries are totaled to thirteen, i.e. Han River(including Imjin River), Anseongcheon, Sapgyocheon, Geum River, Mankyeong River, Dongjin River, Yeoungsan River, Tamjin River, Seomjin River, Gawhacheon, Nakdong River(including West Nakdong River), Taewha River, and Hyeongsan River estuaries. The Regional 1st Class River scale estuaries are counted as four, i.e. Yeoungdeok Osipcheon, Samcheok Osipcheon, Gangneung Namdaecheon, and Yangyang Namdaecheon. While, the Regional 2nd Class River estuaries are arranged as the Province and counted as total 444; Jeonnam, Gyeongnam, Chungnam, Jeju Province have the 108, 94, 52, and 35 estuaries, respectively. The counted estuary numbers, however, can be slightly increased/decreased on what references are applied, e.g. whether or not including the streams lost estuary functions by the sea-dike construction or integrated nearby streams, and so on.

• Proceedings of the Korean Society of Organic Agriculture Conference
• /
• 2009.12a
• /
• pp.45-56
• /
• 2009

Current status on the occurrence and the management of the major disease, insect and mite pests were investigated in the organic or non-chemical pest control orchards from 2005 to 2009. Numbers of certified organic or non-chemical apple orchards were increased from 14 in 2005 to 78 in 2008. Severe damages on leaves and fruits occurred by the several diseases such as marssonina blotch, bitter rot, white rot, sooty blotch and flyspeck, and the several insect pests such as apple leaf-curling aphid, woolly apple aphid, oriental fruit moth and peach fruit moth on the almost certified organic or non-chemical pest control orchards. About 10 and 18 environmental-friendly materials were used to control diseases and insect or mite pests respectively. But, lime sulfur and bordeaux mixture to diseases and machine oil, plant oil mixed with egg yolk, and pheromone mating disruptions to insect pests were effective to control under the adequate conditions. At present, it is extremely difficult to produce organic apples in Korea. Growers must consider about and solve so many conditions on the cultivar, weather, local site, marketing and so on, before when they decide to change from conventional or IPM(Integrated Pest Management) to organic or non-chemical pest control orchards.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.13 no.1
• /
• pp.10-19
• /
• 2011

In order to predict the risk of anthracnose on hot pepper in the future, the projected climate data from SRES A1B scenario in South Korea were used with the modified anthracnose model to calculate Infection Risk (IR), which was to estimate the number of fungicide sprays. Based on daily temperature and precipitation, the anthracnose model resulted in an empirical relationship that IR = (Daily temperature - $16^{\circ}C$) ${\times}$ 0.07 + (Daily precipitation ${\times}$ 0.11). For 135 locations in South Korea, the total number of fungicide sprays needed from 2011 to 2100 was 12,150, indicating a complicated change with an overall increase in anthracnose development in all locations until 2100. In particular, radical changes in anthracnose development were predicted at Yeongdeok, Yeongyang, and Uiseong, whereas gradual changes were predicted at Heongsung, Hamyang and Taean. The eastern counties of Gyeongbuk Province, which ar the major plantation area in these days, would be the place with the highest disease pressure in the future. In addition, the years of 2058, 61, 78 and 2096 will be most severe, requiring 8-11 times of fungicide spraying. The GIS maps show that the mountain areas of Jeonbuk and Chungbuk Province would have the least disease pressure of anthracnose in the future.

• Parasites, Hosts and Diseases
• /
• v.35 no.3
• /
• pp.171-180
• /
• 1997

Studies on geographical distributions and relative population densities of the vector mites of tsutsugamushi disease were carried out in October 1996 at 12 locations of the mid south inland of the Korean peninsula, where chigger mites have been never studied. Of 177 field rodents and insectivores collected. 154 (87.0%) were Apodemus ngrarius. Total 25,707 chigger mites were collected and 14 species were identified. of which Leptotrombidium pnllidum was predominant (79.8%) and L. palpate the next (8.9%) . L. pallidum, the vector species, was widely distributed in all study areas, showing the highest density at Cho-o 2-dong, Sangju-si (chigger index 201.8), and the lowest at Tanwol-dong. Chungiu-si (chigger index 40.7) . The other vector species, L. scutellare was found only at the southern part of the study area such as Yobae and Mipyong, Kumrung gun and Vnsu , Kimchon-si. The northernmost areas of the L. scutellcre distribution were coincided with the areas where actual mean air temperature is above 10.0%. Among 157 A. ograrius sera tested, 48.3% was Karp, 1.7% william and 3.3% Kuroki. The rest of the sera were not able to determine the sexto-type because of the cross antigen-antibody reactions among the tested sero-types.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.12 no.3
• /
• pp.157-172
• /
• 2010

Using 61 observation data of the recent 30 years from 1979 to 2008, we have identified the areas which had climatologically frequent occurrence of extraordinary low and high temperature leading to meteorological disasters. The station of the highest temperature deviation was Gangneungduring the period of April through July. Furthermore, the eastern coast region including Gangneung recorded the largest amplitude of temperature deviation in Korea, showing the climatological evidence that the temporal variation was the largest. During the period of April to October, most of the days with extraordinary high temperature were found in April. The regionswith more than 30days of extraordinary high temperature werethe eastern and western coast regions. Thus, special attention to prevent the meteorological disaster related to extraordinary high temperature is required in the coast regions particularly during April. Meanwhile, further attention to prevent the disaster related to extraordinary low temperature is required in Gangwon inland, Chungcheong inland, and the southern province especially in August.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.32 no.2
• /
• pp.163-172
• /
• 1987

Results obtained from this study conducted to find the effect of wind-break net on reducing cold wind damage in the eastern coastal cold wind damaged area are summarized as follows. The rice critical safe heading date was up to Aug. 10 in the eastern coastal area, which the frequency of gale Aug. 10 to Sep. 10 is high. The frequencies of westries and cold wind from sea were 25%, respectively, in this area. The effects of wind-break net on reducing wind verocity were 26.9, 34,6% with raising air temperature of 0.4-0.7$^{\circ}C$ and water temperature of 0.3-0.5$^{\circ}C$. The effect of wind-break net was up to 10 time's distance of wind-break net's height from wind-break net. The installation of wind-break inhanced to rice growth, so showed the heading date earlier by 2-5days and increased culm length, no.of panicles per hill and no. of spiklets per panicle. The yield decrease in this area was due to sterilization, poor ripening and light 1,000 grain weight. The yields showed 20-28% increase by installation of wind-break net. The effect of wind-break net was most in the installation plot with wind-break net against cold wind from sea and westries installed in the panicle formation stage.

• Korean Journal of Environmental Agriculture
• /
• v.10 no.1
• /
• pp.59-66
• /
• 1991

This study was carried out to investigate the chemical characteristics of the rain water in rural, urban and industrial areas which are located in Kyongbuk province, namely. Songju, Kumi, Kimchon, Yongdok and Teagu. The experiments were sampled the rain by amount of rain water from July to August in 1989, and analyzed the pH. EC, $SO_4\;^{2-}$, $NO_3^-$ and $Cl^-$ contents in the rain water. The results are summarized as follows : 1. The acid rain showed at the begining rain water of all surveyed sites, but there were difference by sites, and particulary severe in Kumi. 2. The content of $SO_4\;^{2-}$ in rain water was high in urban and industrial area, such as Teagu, Kumi and Kimchon. 3. According to the increasing rain water amount, the pH in rain water was high, and the contents of other components were low. This phenomenon remarkably presented at higher concentration of components and earlier rain water. 4. The electric conductivity was high significantly positive correlation with contents of $SO_4\;^{2-}$, $NO_3\;^-$ and $Cl^-$ in rain water, and pH was high significantly negative correlation with contents of $SO_4^{2-}$ and $NO_3\;^-$ in rain water, respectively.

• Geophysics and Geophysical Exploration
• /
• v.12 no.3
• /
• pp.225-232
• /
• 2009

As part of seismic experiments investigating crustal velocity structures of the Korean peninsula, permanent (fixed) seismographs of the Korea Meteorological Administration (KMA) network recorded seismic signals from four and eight large explosions in Korean Crustal Research Team (KCRT) profiles shot in 2004 and 2008, respectively. Among the seismograms recorded by 43 velocity sensors and 103 accelerometers at KMA stations distributed throughout the southern Korean Peninsula, 156 records with epicentral distances less than 120 km and high signal-to-noise ratios were analyzed to determine velocity anisotropy of the Pg phase. Relative elevation corrections of -101.6 to 105.3 ms were made using velocity information derived from the 2004 KCRT profile data and differences in elevation between the permanent KMA stations and the temporary stations in the KCRT profiles at the same source-receiver offsets. To remove site effects, receiver-station corrections of -89.6 to 192.2 ms were additionally made to the KMA station data by subtracting the average differences in traveltimes between KMA stations and portable stations at the same offsets for all available shots with different azimuths. With the exception of anomalously fast velocities along trends of the Chugaryeong fault zone and the Okchon fold belt and anomalously slow velocities in the regions of high terrestrial heat near Yeongduk and Ulsan, the analysis of crustal velocity anisotropy using the Pg phase indicates overall isotropy in the southern half of the Korean peninsula.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.585-588
• /
• 2008

To predict the service life of reinforced concrete structures exposed to chloride environment, quantitative measures of material properties such as the critical chloride content for corrosion in concrete and the diffusion coefficient of chloride ions of concrete and the surface chloride content of the concrete are essential. However, it should be noted that they are influenced by several factors such as concrete mix proportions, cement type, and environmental conditions, etc. Thus, the purpose of this research is to estimate more actually the critical chloride content for corrosion of the reinforcing steel in concrete by field exposure experiment. For this purpose, the prism concrete test specimens were made for water-cement(W/C) ratios of 31%, 42%, 50%, and 70%, and then the field exposure experiment for them were conducted at Youngduk of the east coast for about 3 years. During the test, corrosion monitoring by half cell potential method was carried out to detect the time to initiation of corrosion for test specimens and its chloride content was evaluated by breaking the concrete test specimens when corrosion of the reinforcing steel in concrete was perceived. It was observed from the test results that the critical chloride content for corrosion of reinforcing steel in concrete would be dependent on W/C ratio and almost irrespective of concrete cover.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.10 no.4
• /
• pp.177-186
• /
• 2008

This study was carried out to analyze the relationship between major climatic factors (temperature and precipitation) and tree ring growth of Pinus densiflora in 28 cities and counties in Korea. To examine tree ring growth of Pinus densiflora and the response of the climatic factors to climate change, the regional climatic data (for how many years??) from weather stations were categorized by five groups using cluster analysis for major climatic factors. In terms of relationship between monthly average temperature and tree ring growth of Pinus densiflora, negative correlations were observed for the temperatures in March of the present year in Baekdudaegan region and those in February and March in Gyeongbuk and East coast region. In addition, the temperature in October of the previous year was also negatively correlated with tree ring growth. Precipitation was positively correlated with the April and June temperatures of the present year in Baekdudaegan region and Gyeongbuk, respectively. Precipitation effect on the tree ring growth with current year June in Honam and Gyeongnam inland region and June, September in East coast region.