• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.116-118
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• 2011

해안가에 건설되는 구조물 표면은 해풍에 의해 직접적인 영향을 받는다. 해풍에 섞여 날아오는 염분이 건축물 외부에 흡착하여 시간이 경과함에 따라 내부로 확산 이동하게 되어, 콘크리트 내부의 철근이 부식하게 된다. 따라서, 해안가 구조물의 비래염분에 대한 열화 예측을 보다 정확하게 조사하기 위해서는 실환경하에 작용하는 기상요인, 지형, 구조물의 형태 등 대상지역의 다양한 조건을 정밀하게 반영하여 정해야 할 필요가 있다. 풍향, 풍속, 온도, 습도등의 다양하게 변화하는 기상요인에서 각 요인에 따라 발생되는 비래염분량과의 상관성을 분석하기 위해서는 고정된 실험인자에 따른 지속적인 실험이 필요하다. 따라서 본 연구는 비래염분 포집기 개발 및 인공비래염분 발생장치(이하, 인공장치) 개발과 장치 성능의 정확성 향상을 위한 기초 실험 실시에 목표를 하였고, 또한 개발된 비래염분 포집기를 실 환경에 설치하여 각 실험인자에 따른 실환경에서의 비래염분 포집량을 분석하고자 한다.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.769-776
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• 2010

Concrete structures immersed in seawater are exposed to uniform chloride concentration. However, seashore concrete structures are subjected to various airborne chlorides concentration depending on areas, distance from seashore, orientation of structures and wind direction etc. Therefore, structures which is not coming into direct contact with seawater are greatly affected by salt attack and those cases have been reported. This study intends to investigate salt attack by airborne chlorides in terms of the distance from the seashore based on the measurements conducted at 73 spots and 27 areas during 3 years in the Eastern, Western and Southern coasts of South Korea. Results revealed large regional variations of the salinity in coastal regions along with significant seasonal effects caused by seasonal winds. Moreover, the salinity is seen to diminish as the distance from the seashore increases at a rate corresponding to the function $y=ax^{-b}$. These results will be helpful to do the durability design and management of seashore structures.

• Korean journal of applied entomology
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• v.41 no.4
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• pp.247-253
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• 2002

Based on accumulated data during 1977-2001, seasonal fluctuations of migrated aphids at Daegwallyeong highlands were analyzed. In addition, rates of PLRV transmission by migrated aphids were investigated by inoculation on indicator plant, Physazis floridana, and ELISA in 2000-2001, and the change of PLRV transmission rates by aphids was compared with that of 1989-1991. The average migrated aphid population densities in 1976-1980, 1991-1995, and 1996-2000 were 575.2, 2959.4 and 2281.6, respectively, showing gradual increase in recent years. The average peak time of aphid migration was from early to mid June during 1977-2001, showing any significant differences over the years. The dominant species, however, changed slowly; before mid 1980s M. persicae flied dominantly, but after mid 1980s Aphis gossypii did. Hahm et al. (1991) reported that PLRV transmission rate of migrated aphids during 1989-1991 was 6.7-10.0%. In 2000-2001, however, migrated aphids at Daegwallyeong highland showed 10.1-11.0%. Although present PLRV transmission rate was slightly higher than that of 10 years ago, taking increased population densities and diversity of migrated aphids into account, there was no significant change of PLRV transmission rate over the years.

• Research in Plant Disease
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• v.24 no.3
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• pp.202-212
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• 2018

Major viruses infecting rice are transmitted by planthoppers such as small brown planthopper (SBPH), brown planthopper (BPH) and white-backed planthopper (WBPH). In this study, we investigated planthoppers captured during 2015 to 2017 by a smart sky net trap (SSNT) system installed in 40 areas in Korea, which is an automatic, rapid and real-time insect surveillance system. The average rates of captured migration plnathoppers was 27.5%, 17.2%, 15.3% and 10.9% in Chungcheongnamdo, Jeollanamdo, Jeollabukdo and Gyeonggido, orderly. The highly migrated month was July for SBPH, July to August for WBPH and August for BPH. To investigate the viruliferous rates of planthoppers of rice during 2015 to 2017, we performed RT-PCR using specific primers for each rice virus. RBSDV was detected from 0.4% in SBPH, while no viruses were detected in BPH and SBPH. Rice planthoppers exist all around in Asia. They can move long distance by wind from southern countries to Korea. Monitoring the migration of rice planthoppers and their viruliferous rates is important to prevent the outbreaks of rice virus diseases.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.627-633
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• 2011

Evaluation of the amount of chloride ion coming from the sea is very important in assessing the life expectancy of Reinforced Concrete structures. Developed in Japan, the incoming salt collector has been used to this day. Unfortunately, the incoming salt collector has had a bad reputation, which is caused by backward wind. Backward wind causes a reduction of the amount of salt collected in collector's gauze. The collector was developed to eliminate the effect of backward wind. Simulation test in the laboratory and site measurement were performed to determine the amount of incoming salt according to the height. The performance was verified through analytic and experimental methods.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.553-558
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• 2012

Airborne chlorides are transported to inland by sea wind to be attached to seashore concrete structure surface then penetrated into concrete structure members. Since the surface attached chloride amount are dependent on the amount of airborne chlorides, the prediction of distribution of airborne chlorides is important information in preventing chloride corrosion problems in seashore concrete structures. The prediction of surface chloride amount from airborne chlorides environment is extremely difficult than concrete directly in contact with seawater. In addition, their penetrating tendency is different from that of concrete immersed in seawater. In this study, properties of surface and penetrated chlorides under airborne chlorides environment are investigated. Concrete specimens were manufactured and exposed to marine environment for 3 years. The specimens were analyzed at the time durations of 1, 2, and 3 years to check surface chloride amount to penetrated chloride depth. The results revealed that there were certain differences according to surface roughness of concrete and with and without washing effect due to rainfalls. The evaluation results showed that penetrated chlorides depend on amount of airborne chlorides and duration of exposure. In addition, a notable tendency of having deeper chloride penetration and higher chloride content in concrete members under long-term exposure was observed.

• Korean journal of applied entomology
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• v.27 no.4
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• pp.200-210
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• 1988

ABSTRACT Brown planthopper collection data by 151 light traps located throughout the southern part of Korean peninsula for 7 years from 1981 thru 1987 were analysed with each immigration wave in relation to daily weather charts when the immigration occurred, and summarized as below. 1) Most of the main immigration took place during the mid and late July, though there were some variations from year to year. 2) Number of the BPH collected at one time, and the number of the area where those immigrants where collected were increased when it occurred closer to the end of July. 3) Weather conditions when the immigration took place were divided into 4 types; (a) depression with stationary front passed over the central peninsula (A type, 12 times); (b) depression with stationary front passed over the southern sea (B type, 5 times); (c) stationary front passed over the central peninsula(C type, 7 times); (d) without depression and stationary front (D type, 2 times). 4) Whatever the types of the weather, those immigrations started to land from south-west part of the peninsula, and those numbers of immigrants were also grater at those south-western areas. 5) When common weather factors were counted from each weather chart of the days when thcse immigrations took place, presence of wind from south-west was 26 times, presence of stationary front was 24 times, and presence of depression was 17 times out of all 26 cases of immigration. 6) Therefore, it could be concluded that the immigration of the BPH into Korea is simply accompanied by the north$.$easterly flowing air currents, connected from south-east part of China through Korean peninsula. And other factors seem to be related with inducing their landing.anding.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.221-228
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• 2021

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is a notorious invasive migratory pest native to the tropics that has recently invaded South Korea with subsequent damage to cornfields. This study was conducted to evaluate the damage patterns on corn plants caused by the migratory and subsequent generations of FAW. The early migrant generation-related infestation rates reached an average of 13.2%, ranging from a minimum of 4.3% ('Allog-i') to a maximum of 33.0% ('Chodang'), depending on the corn cultivar. The proportion of FAW larvae-infested corn plants, in which the FAW survived until the pupal stage was 19.3%. The subsequent FAW generation caused considerable damage to the ears, resulting in 60% of ears with damaged kernels. This damage was markedly different from the nearly negligible damage caused by the migratory generation. The FAW larval dispersion was the most dynamic during the second instar stage and occurred along the same cornrow in line. In addition, we discuss the development of corn pant damage patterns caused by FAW. In summary, the results of the present study would provide useful basic information for the damage analysis of this pest for future studies.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.415-426
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• 2023

In this study, the horizontal and vertical structure of wind speed and wind direction were analyzed at the origin of migratory insect pests in China. Wind rose analysis was carried out using the Land-Atmosphere Modeling Package (LAMP) - WRF data, which has the spatiotemporal resolution of about 20 km and 1 hour intervals. Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) was employed for backward trajectory analysis between South Korea and Southeastern China with Global Data Assimilation System (GDAS). The research interest date is July 16, when rice planthopper and leafhopper were observed at the same time. In order to examine where a jet stream occurs in the vertical in source regions and South Korea during the period (July 8 to July 17 in 2021), three-dimensional wind information was extracted and analyzed using the east-west, north-south, and vertical component wind data of the LAM P. The vertical distribution of wind showed that the wind changed in favor of the inflow of migratory insect pests during the period. As a result of analyzing the wind rose, about 30% or more of the wind at a point close to South Korea was classified into the low-level jet stream. In addition, majority of the wind directions for the low-level jet streams (rather than high-level jet streams) at the five origin sites were heading toward South Korea and even Japan, and this was supported by the HYSPLIT-based backward trajectory analysis.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.98-99
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• 2014

The newly developed eight-directional collector was installed at five different locations in the coastal area after its functionality was verified through experiments. Based on the airborne chloride amount measured for one year, the distribution characteristics of airborne chlorides were examined by direction. In terms of direction, a large amount of airborne chlorides was collected, not only in the direction facing the coast but also in the opposite direction. The amount measured at effective three directions was 1.5 times that measured at non-effective three directions.