• 한국물환경학회지
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• 제21권6호
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• pp.584-594
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• 2005

The spatio-temporal abundance pattern of algae in Lake Paldang from 2002 to 2004 was investigated. The concentration of chlorophyll a representing algal biomass had fluctuated intensively throughout the year. Among three years, the highest algal biomass was shown in 2002, and typical growth peak of concentration of chlorophyll a was occurred in spring and autumn. There had been frequent rainfall in spring drought period in 2003 and it resulted in the decrease of the algal biomass. The distribution pattern of four algal groups on the surface water of Lake Paldang showed different abundance by season and by water area. In particular, different algal growth characteristics by water areas were observed. Influences of various environmental parameters on algal abundance in four water areas of Lake Paldang were analyzed statistically. From the results of Peason correlation analysis, it was understood that the kinds and affects of environmental parameters were different according to water areas and seasons. Based on the factors analysis of environmental parameters on the concentration of chlorophyll a, stepwise regression models whose independent variables were the factors produced by factor analysis and dependent variable was the concentration of chlorophyll a were derived by water areas and seasons. As a whole, factors related with organics and photosynthesis were revealed to have high affects to algal abundance, whereas limiting nutrients such as phosphorus and nitrogen showed little affect in Lake Paldang.

• 한국농공학회논문집
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• 제53권4호
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• pp.1-9
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• 2011

Forest area covers 64 % of the national land of Korea and the forest plays a pivotal role in the hydrological process such as flood, drought, runoff, infiltration, evapotranspiration, etc. In this study, soil moisture monitoring for conifer forest in experimental forest of Seoul National University has been conducted using FDR (Frequency Domain Reflection) for 6 different soil layers, 10, 20, 30, 60, 90 and 120 cm during 2009~2010, and precipitation data was collected from nearby AWS (Automatic Weather Station). Soil moisture monitoring data were used to estimate soil moisture recession constant (SMRC) for analyzing soil moisture recession characteristics. From the results, empirical soil moisture recession equations were estimated and validated to determine the feasibility of the result, and soil moisture contents of measured and calculated showed a similar tendency from April to November. Thus, the results can be applied for soil moisture estimation and provided the basic knowledge in forest soil moisture consumption. Nevertheless, this approach demonstrated applicability limitations during winter and early spring season due to freezing and melting of snow and ice causing peculiar change of soil moisture contents.

• 한국환경복원기술학회지
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• 제14권2호
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• pp.1-10
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• 2011

Six pine trees (Pinus densiflora S. et Z.) at the Euilimji Lake Park in Jecheon were collected to investigate tree ages, growth decline pattern and the years of death. Tree-ring measurement was carried out using the Lintab with a resolution of 0.01mm. Tree age were 80-176 years. Cross-dating between the tree-ring series of each tree and the local chronology from Worak Mountain resulted that four and two trees died in 1998 and 1999, respectively. Three dead trees had only formed earlywood in the outermost tree ring and the others had incomplete latewood. Therefore, it was proven that the former trees died between spring and early summer, whereas the later ones died during late summer and/or autumn. The simultaneous deaths of trees suggest the insect damage and/or drought may be the crucial reason of the death, but frequent reaction woods, which were formed by leaning stem, and scars formed by physical damage may also contribute to the death.

• 아시안잔디학회지
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• 제9권3호
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• pp.173-185
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• 1995

Hydroseeding technique is a very popular method of revegetating slope areas through the control of soil erosion and stability by seeding grasses. This study was conducted to select turfgrass species and cultivars for hydroseeding. Experiment plots were established on various soil types and environmental conditions at Singar-Ansan high-way construction site. The investigation was designed in three cutting, one back-filling and other three spare sites with various seed mixtures. Results indicated that combinations of seed mixtures influenced seed germination and rates of surface cover. In a view of long term, vegetation shifts should be influenced by characters of slopes and micro-climate conditions. Hydroseeding did not show good results on rocky slope areas. Revegetation was only going on where there had soil. The combination of seed mixture with a higher rate of perennial ryegrass had relatively good revegetation with faster germination and seedling growth. Improved turf-type tall fescue Arid ⓡ and Falcon ⓡ seemed to have good environ-mental adaptation and drought tolerance. Wild or old type cultivars showed relatively slow green-up in spring and growth rates at the next year of seeding. For the harmonious landscaping with surrounding area, the combination of native grass mixture with cool-season grasses had good results. Slow and low revegetation rate at hack-filling site seemed to be caused by the poor development of capillary tubes in sub-soil. It was shown that a high correlation between seed germination and revegetation rate, and between three-month later coverage rate and final rate. The evaluation of coverage rate after three month seems to he acceptable to decide the accomplishment of hydroseeding results on rode side slopes.

• 식물병연구
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• 제8권1호
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• pp.1-10
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• 2002

2001년 기상의 특징은 3월부터 5월까지 계속된 극심한 가뭄과 생육기간 내내 계속된 고온현상 그리고 별다른 태풍의 내습 없이 9, 10월 수확기 맑은날의 지속으로 요약할 수 있다. 벼는 순조로운 기상 때문에 잎, 이삭도열병, 세균성벼알마름병, 흰잎마름병, 잎집무늬마름병의 발생이 예년에 비해 경미하였으나, 감비추진 정책에 의해 생육후기 깨씨무늬병이 발생하여 전국적으로 문제시되었으며 그동안 발생이 적었던 줄무늬잎마름병이 경기, 충청, 호남 서해안지역을 중심으로 많이 발생하였다. 고추는 생육기 비가 많이 왔던 전남북 지역에서 역병 발생이 심하였으며 토마토와 오이는 대부분 예년에 비해 병발생이 적었다. 수박의 경우는 꽃자리 부분이 썩는 푸른곰팡이병이 전국적으로 발생하였으며 CGMMV는 전년에 비해 상당폭 발생면적이 감소하였고 노지재배의 경우 탄저병 발생이 예년에 비해 심하였다. 참외와 딸기도 전년에 비하여 병발생이 경미하였으며 예년에 발생이 많았던 참외의 급성위조증상도 발생이 대폭 감소하였다. 마늘·양파의 흑색썩음균핵병은 봄철의 가뭄과 고온현상으로 병발생의 전년의 절반수준으로 감소하였다. 감자의 풋마름병은 발병포장이 증가하는 경향이었으며 고구마의 덩굴쪼김병도 발생이 감소하였다. 사과의 경우 전반적으로 병 발생이 예년에 비해 경미하였으며 배는 흰가루병이 많이 발생하였다. 맥류의 붉은곰팡이병은 예년처럼 거기 발생이 없었다.

• 한국농림기상학회지
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• 제23권4호
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• pp.316-328
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• 2021

본 연구에서는 간척지의 염분 모니터링을 위한 다중 분광 센서를 개발하기 위해 400~1000 nm 초분광센서를 사용하여 봄 감자의 잎 Na 함량 예측 모델을 구축하고자 하였다. 관개조건은 표준, 한해, 염해(2, 4, 8 dS/m)로, 관수량은 증발량을 기준으로 산정하였다. 영양생장기, 괴경형성기, 괴경비대기에 각각 관개를 시작한 후 1주와 2주 후에 잎의 Na 함량을 측정하였다. 잎의 반사율은 10nm 파장 간격을 기준으로 5 nm에서 10nm, 25nm, 50nm FWHM (full width at half maximum)으로 변환되었다. PLS-VIP를 사용하여 봄 감자 잎의 Na 함량에 따른 염분 피해 수준을 예측하기 위한 10개의 밴드비가 선택되었다. 선택된 10개의 밴드비 중 가중치가 가장 낮은 순서대로 밴드비를 하나씩 제거하면서 MLR모델을 추정하였다. 모델의 성능은 R2, MAPE 뿐만 아니라 밴드비의 수, 다중 분광센서를 작게 만들기 위한 최적의 FWHM 수로 비교하였다. 1, 2주차의 영양생장기, 괴경형성기와 2주차의 괴경비대기에서 봄 감자의 잎 Na 함량을 예측하기 위해서는 25 nm의 FWHM을 사용하는 것이 유리하였다. 선택된 밴드필터는 430/440, 490/500, 500/510, 550/560, 570/580, 590/600, 640/650, 650/660, 670/680, 680/690, 690/700, 700/710, 710/720, 720/730, 730/740 nm로 Red 및 Red-edge 영역에서 15개 밴드비가 선택되었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.267-267
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• 2017

In Korea, the average air temperature has been elevated twice faster than the average global warming. And the climate warming is characterized by the smaller rise of air temperature in summer and the greater rise of air temperature in spring and winter. Therefore, the number of frost-free days to determine the cultivation ability of crops has increased by more than 15 days in 10 years according to climate warming. This climate warming trend has extended and is projected to extend not only the sweet potato growing season but also the sweet potato early cultivating area to higher altitude and latitude region. This study was carried out to evaluate the possibility of sweet potato double cropping in the southern island area of Korea by assessing the growth and yield performance of sweet potato cultivated at extremely-early and -late time. We had performed at Yokji Island Yokji Island($E128^{\circ}$ 18' $N34^{\circ}$ 36'), a representative specified complex area of sweet potato cultivation in southern Korea. As the test varieties, the major cultivars of the this region, Shinyulmi and early hypertrophic cultivars, Dahomi were used. The prior cropping were planted with PE film mulching on March 30 and April 10, and harvested after 110 days. So the succeeding cropping were planted without PE film mulching on July 25 and August 5 according to the harvesting time of the prior sweet potato and harvested after 120 days. As a control, it was harvested on September 15, 120 days after planted on May 15. Each experimental plot had an area of 12 square meters consisting of 4 beds, and was planted one at a time at intervals of 25cm. We had investigated growth characteristics - main vine length, node number, branch number, total vine yield, and tuberous root characteristics - tuberous root number, average weight, starch value, and etc. After harvesting, we analyzed the economic effects by examining the postharvest quantity, the input labor, the management cost, and the income. The total yield of marketable products in prior and succeeding cropping was 46~70% higher than that of control. The average unit price of sweet potato was 36% higher than the conventional culture, and the gross income increased by 98%, but the operating cost increased by 83%, and the farm income increased by 103%. There are considerations such as the difficulty of enlargement of cultivation area due to lack of labor in limited space and the need for watering measures due to spring drought. However, if the area of application for sweet potatoes double system is increased by 10%, it can be used as a new cropping system.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.280-280
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• 2017

In Korea, the average air temperature has been elevated twice faster than the average global warming. And the climate warming is characterized by the smaller rise of air temperature in summer and the greater rise of air temperature in spring and winter. Therefore, the number of frost-free days to determine the cultivation ability of crops has increased by more than 15 days in 10 years according to climate warming. This climate warming trend has extended and is projected to extend not only the sweet potato growing season but also the sweet potato early cultivating area to higher altitude and latitude region. This study was carried out to evaluate the possibility of sweet potato double cropping in the southern island area of Korea by assessing the growth and yield performance of sweet potato cultivated at extremely-early and -late time. We had performed at Yokji Island Yokji Island($E128^{\circ}$ 18' $N34^{\circ}$ 36'), a representative specified complex area of sweet potato cultivation in southern Korea. As the test varieties, the major cultivars of the this region, Shinyulmi and early hypertrophic cultivars, Dahomi were used. The prior cropping were planted with PE film mulching on March 30 and April 10, and harvested after 110 days. So the succeeding cropping were planted without PE film mulching on July 25 and August 5 according to the harvesting time of the prior sweet potato and harvested after 120 days. As a control, it was harvested on September 15, 120 days after planted on May 15. Each experimental plot had an area of 12 square meters consisting of 4 beds, and was planted one at a time at intervals of 25cm. We had investigated growth characteristics - main vine length, node number, branch number, total vine yield, and tuberous root characteristics - tuberous root number, average weight, starch value, and etc. After harvesting, we analyzed the economic effects by examining the postharvest quantity, the input labor, the management cost, and the income. The total yield of marketable products in prior and succeeding cropping was 46~70% higher than that of control. The average unit price of sweet potato was 36% higher than the conventional culture, and the gross income increased by 98%, but the operating cost increased by 83%, and the farm income increased by 103%. There are considerations such as the difficulty of enlargement of cultivation area due to lack of labor in limited space and the need for watering measures due to spring drought. However, if the area of application for sweet potatoes double system is increased by 10%, it can be used as a new cropping system.

• 대한원격탐사학회지
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• 제28권3호
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• pp.267-276
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• 2012

Terminal lakes are widely distributed in the arid and semi-arid Gobi of Mongolia, and serves as important water resource for local people and livestock. However, such lakes are subject to great fluctuations in its size depending on climatic conditions and human water utilization. The Orog Lake is one such example that has shown remarkable fluctuation in recent years. In this study, we investigated the temporal changes of Orog Lake surface area by using 16-day MODIS 250 m NDVI products from 2000 to 2010. The results were compared with climate variability represented by monthly precipitation and temperature. Our results show that the Orog Lake gradually shrank for the period from 2000 to 2010, but with a significant range of seasonal and inter-annual variability. The lake area showed considerable seasonal variations, as it expanded in spring and fall, primarily due to snow melt and summer precipitation, respectively. Extreme drought period from 2000 to 2002 triggered the substantial reduction in lake area, leading to dry-up in year 2005, 2006, 2007, and 2009. After dry-up once occurred in 2005, the lake repeated reappearance and disappearance depending on seasonal and annual precipitation. Our findings implicate that the ground water fluctuated around the lake bottom level since 2005. This suggests the highly vulnerable nature of Orog lake, which greatly depends on future precipitation change.

• 한국작물학회지
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• 제46권2호
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• pp.130-133
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• 2001

The purpose of this study was to investigate the decreased ratio of growth and yield by delayed seeding and flowering because drought of spring season often cause to delay seeding and sprout emergence. Equation of linear regression, y=-11.914x＋818.61 ($R^2$=0.916) and y=-16.96lx＋913.98 ($R^2$=-0.885) were derived from relationship between sowing date and yield of leading variety, Yangbaeckkae in 1999 and 2000, respectively. Yield was decreased by 7, 24, 40, 57, 74%, respectively, according as sowing date was delayed more 5, 15, 26, 36, 46 days than May 15, standard sowing date under the culture mulched with black P.E. film. Number of capsules per plant and length of stem bearing capsule were greatly decreased, while plant height, stem diameter, and day to flowering were affected little by delayed seeding date. Equation of linear regression, y=-0.7081x＋41.04 ($R^2$=0.861) was derived from relationship between flowering date and yield of 33 accessions. Yield was decreased by 7.7, 8.3, 9.2, 10.1, 11.2%, respectively, according as flowering date was delayed more 1, 2, 3, 4, 5 days than July 3, normal flowering date of Yangbaeckkae when it was sown on May 15, and the more flowering date was delayed, the more yield was decreased. Number of capsules per plant and length of stem bearing capsules were greatly decreased, but plant height and harvest index were decreased little by delay of flowering date