• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.6
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• pp.118-125
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• 2011

This study was conducted to check danger of the cold injury by reviewing the lowest temperature by regions and the cold tolerance of Lagerstroemia indica and Pyracantha angustifolia. The cold tolerance of the samples treated at low temperature was evaluated by measuring electrical conductivity and observing browning of the cambium. It was proved that the lethal temperature of L. indica is below $-17.1^{\circ}C$, and that of P. angustifolia is below $-18.9^{\circ}C$. The frequency of the lowest temperature went down below $-17.1^{\circ}C$, was 7 times in Daejeon, 55 times in Cheongju and 72 times in Suwon for the last 45 years. In Daejeon, it has happened only once since 1975. The temperature dropped below $-18.9^{\circ}C$ 45 times in Cheongju and 32 times in Suwon during the same period, but it has not happened at all since 1991. It appears that the rising coefficient of the lowest temperature increases, as the latitude gets higher. As a result, L. indica and P. angustifolia which were planted in the central region of Korea, are considered in danger from freezing injury because the temperature can get very low intermittently in winter. But, the risk of freezing has reduced gradually as the lowest temperature raises each year.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1B
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• pp.29-36
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• 2011

Evapotranspiration (ET) from the various surfaces needs to be understood because it is a crucial hydrological factor to grasp interaction between the land surface and the atmosphere. A traditional way of estimating it, which is calculating it empirically using lysimeter and pan evaporation observations, has a limitation that the measurements represent only point values. However, these measurements cannot describe ET because it is easily affected by outer circumstances. Thus, remote sensing technology was applied to estimate spatial distribution of ET. In this study, we estimated major components of energy balance method (i.e. net radiation flux, soil heat flux, sensible heat flux, and latent heat flux) and ET as a map using Mapping Evapo-Transpiration with Internalized Calibration (METRIC) satellite-based image processing model. This model was run using Landsat imagery of Gyeongan watershed in Korea on Feb 1, 2003 and Sep 13, 2006. Basic statistical analyses were also conducted. The estimated mean daily ETs had respectively 22% and 11% of errors with pan evaporation data acquired from the Suwon Weather Station. This result represented similar distribution compared with previous studies and confirmed that the METRIC algorithm had high reliability in the watershed. In addition, ET distribution of each land use type was separately examined. As a result, it was identified that vegetation density had dominant impacts on distribution of ET. Seasonally, ET in a growing season represented significantly higher than in a dormant season due to more active transpiration. The ET maps will be useful to analyze how ET behaves along with the circumstantial conditions; land cover classification, vegetation density, elevation, topography.

• Korean Journal of Plant Tissue Culture
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• v.28 no.6
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• pp.317-321
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• 2001

This study was carried out with Lilium oriental hybrid cv. Casa Blanca to observe the effect of in vitro culture conditions on ex vitro sprouting of bulblets. Low temperature (15$^{\circ}C$) inhibited the growth of in vitro bulblets while high temperature ($25^{\circ}C$) enhanced the growth. Bulblets cultured at 15$^{\circ}C$ did not show dormacy while those cultured at 2$0^{\circ}C$ ,$25^{\circ}C$ had a longer dormancy period. High sucrose concentration (9%) induced longer dormancy. Dormancy period was also prolonged in bulblets cultured in vitro at high temperature ($25^{\circ}C$). Dormancy period was more affected by in vitro culture temperature rather than sucrose concentration. Physiological dormancy was released more rapidly when bulblets were cultured at $25^{\circ}C$ for 6 weeks and further transferred at 15$^{\circ}C$ and cultured for another 12 weeks. Treatment of ABA induced the dormancy in Lilium bulblets but when bulblets were subjected to chilling treatment (4$^{\circ}C$ for 8 weeks) nearly 100% sprouting were observed. The medium containing 1.0 mg/L BA or 1.0 mg/L fluridone was also effective to produce non-dormant bulblets.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.169-176
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• 2018

In this paper, we consider duty-cycled wireless sensor networks (WSNs) in which sensor nodes are periodically dormant in order to reduce energy consumption. In such networks, as the duty cycle interval increases, the energy consumption decreases. However, a higher duty cycle interval leads to the increase in the end-to-end (E2E) delay. Many applications of WSNs are delay-sensitive and require packets to be delivered from the sensr nodes to the sink with delay requirements. Most of existing studies focus on only reducing the E2E delay, rather than considering the delay bound requirement, which makes hard to achieve the balanced performance between E2E delay and energy consumption. A few study that considered delay bound requirement require time synchronization between neighboring nodes or a specific distribution of deployed nodes. In order to address limitations of existing works, we propose a duty-cycle scheduling algorithm that aims to achieve low energy consumption, while satisfying the delay requirements. To that end, we first estimate the probability distribution for the E2E delay. Then, by using the obtained distribution we determine the maximal duty cycle interval that still satisfies the delay constraint. Simulation results show that the proposed design can satisfy the given delay bound requirements while achieving low energy consumption.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.85-93
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• 1984

This research was carried out to study the seed dormancy of radishes which were used for summer vegetation. The differences of dormancy of cultivars, maternal effects, the effect of full day length to mother plants, and the effects of chemical treatments for breaking the seed dormancy were considered for this study. These results sere summarized as follows; 1. The germination percentage of 7 cultlvars sown just after harvest were as follows;SP70-:0, PS11-:37.5, GJ75-:75.5, JD127-:77.5, YH85-:81.0, M55-:96.5, and JC73-:98.0%. 2. The dormany of $F_1$ seed of radish was severe when SP70-was used for mother plant. 3. Germination behavior was different by the maturity of plants grown for seed production. The dormancy of seed harvested from immature field-grown plants sown Nov. 10 was deeper than mature plants sown Mar. 22. 4. The germination ratio of tire seed of SP70-radish was increased by treatment of full day length to tire mother plant during full period of growing or since first flowering stage, while that was 0% by treatment since yellow ripening stage. 5. GA 200 ppm+thiourea 0.2% treatment was most effective for breaking of radish seed dormancy.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.205-212
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• 1987

To examine the morphogenetic response, stem segments of 8 Populus spp. and 3 different explants of P. nigra var. italica were cultured on MS (Murashige and Skoog 1962) and WPM (Woody Plant Medium) medium containing various phytohormones. The results obtained were as follows: 1. Shoot regeneration and development from stem segment of 8 Populus spp. showed a quite difference according to the section and the species. All of the species of Leuce and Tacamahaca section did not form adventitious buds, while most of explants showed axillary or dormant bud elongation after 4 weeks. But P. nigra var. italica of Aigeiros section showed a successful adventitious bud formation (mean 5.4 buds per explant). 2. Leaf, petiole, and internode segment of P. nigra var. italica showed a quite differences according to media and ex plants upon the morphogenetic response. Adventitious bud formation from leaf was more abundant and readily initiated on the abaxial side than on the adaxial side. Mean number of 103 adventitious buds per explant was obtained from abaxial side of leaf segment cultured on WPM medium containing $0.2mg/{\ell}$ BAP for 5 weeks. 3. 2,4-D (2,4-dichlorophenoxy acetic acid) supplemented to media appeared to be negative upon the adventitious bud formation of P. nigra var. italica, while it promoted callus formation from all explants. Especially, NAA (${\alpha}$-naphtalene acetic acid) or NAA combination with BAP (6-benzylaminopurine) promoted root regeneration from the all explant of P. nigra var. italica in this study.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.141-145
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• 2013

The aim of this study was to investigate the effect of two male cultivars of asparagus with low different chilling periods on bud breaking, relative spear growth rate, shoot number and yield. Four-month-old plants of two male cultivars of asparagus were dried to impose dormancy and placed in a coldroom at $5^{\circ}C$ to satisfy the chilling requirement for 0, 2, 4, and 6 weeks. After the specified chilling time, the pots were placed in greenhouse. The results showed that mean days to bud break of 'Jersey Giant' significantly decreased with an increasing chilling period from 0 to 6 weeks, but 'Jersey Supreme' was not affected. The relative spear growth rate of 'Jersey Supreme' was significantly stimulated by chilling compared to non-chilled plants. Shoot production and total spear weight of 'Jersey Supreme' tended to be greater than 'Jersey Giant' irrespective of chilling treatments. Following low temperature treatment, 'Jersey Supreme' showed shorter dormant period than 'Jersey Giant', faster growth of spear. The present study showed that asparagus male cultivar at duration of chilling treatment had an affirmative effect on bud breaking, spear growth rates, shoot number and yield of asparagus.

• The Korean Journal of Mycology
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• v.43 no.4
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• pp.281-285
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• 2015

This study was conducted to examine changes in the fungal community on fallen leaves of pear by treatment with lime sulfur. Although the lime sulfur could reduce the primary inoculum of several pathogens on spring season, the effect of lime sulfur has not been well determined scientifically. Fallen leaves infected by pear diseases in pear orchards in Naju were collected and treated with lime sulfur or water as a control. To determine the fungal diversity from each treatment, rDNA internal transcribed spacer (ITS) regions were analyzed after extraction of fungal genomic DNA from lime sulfur-treated or water-treated fallen leaves, respectively. The most common fungal species were Ascomycota and Basidiomycota in both treated leaves. However, the population dynamics of several fungal species including Alternari sp., Cladosporium sp., and Phomopsis sp., which are known as pear pathogens for skin sooty dapple disease, were quite different from each treated leaves. These results indicated that lime sulfur treatment led to changes of fungal communities on pear fallen leaves and could be applicable as a dormant spray.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.45-45
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• 2018

We had already reported the successful germination for green pods of purple lady's slipper orchid (Cypripedium macranthos Sw.). The green pod methods is to take immature seeds in green capsules, sterilize the capsule, and take out the sterile seeds. This method, however, needs very critical time of harvest. The critical time of seed harvest changes depending upon the species, condition of the specimen, and climatic influence, and the right time lies between 5 and 12 weeks after fertilization. In this study, the mature seeds were collected after 120-130 days with hand-polination of lady's slipper orchids. Mature seeds are usually dormant and it has to be overcome, either with hormone or storing the seeds near freezing for two or three months to break dormancy. The seeds were first surface sterilized with 70% ethanol and then transferred 1% NaOCl for 10-15 minutes, followed by rinses 3 times with sterilized distilled water. The cypripedium seeds consists of an embryo within a seed coat known as a testa. The testa is water repellent and the seed has a large air space between the embryo and testa so the seed tends to float on water. We had resolved the problems with vacuum pump to soak water into the testa before sterilization. The seeds were placed on liquid or agar solidified germination media. Cultures were incubated at $24{\pm}1^{\circ}C$ in dark. The seeds were germinated in 6-8 weeks in liquid suspension culture (germination percentage over 18%); however, the seeds on agar solidified media took more than 5 months to germinate and the germination percentage less than 5%. The most effective media for liquid culture was 1/4 strength Murashige and Skoog (MS) medium with 50 ml/l coconut water ($4brix^{\circ}$) at pH 5.8.

• Korean Journal of Environment and Ecology
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• v.30 no.5
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• pp.888-895
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• 2016

The population ecology (Ecological characteristics) of Squalidus chankaensis tsuchigae were investigated at Geum River from March to November, 2013. This species inhabited midstream of the river where was mostly covered with cobble and sand. The depth of the habitat was 30~60 cm and velocity of stream was 2.27~4.88 cm/sec. The sex ratio of female to male was 1 : 0.86. They were sexually mature when they were over two years of age. The spawning period was from June to July with water temperatures from $25^{\circ}C$ to $25^{\circ}C$. Sexually matured individuals appeared over the two year of age. Frequency analysis of total length indicated that the group with 55~70 mm in total length was one year old, the 71~90 mm was two years old, and the group over 91 mm was three years old. The average number of eggs in the ovaries was estimated as 2,219 per matured female. The number of matured eggs size in ovaries was 0.64~0.98 (mean: 0.85) mm. Calulation length-weight relation of S. chankaensis tsuchigae show the value of contant a as 0.0002 and b as 2.81, and condition factor (K) was 1.06 on average. The stomach contents were Cyanophyta, Chlorophyta, Bacillariophyta, Crustaceae, Copepoda, Nematota, Actithocephala, and Ephemeroptera, Hemiptera, Diptera, and Trichoptera that belong to Aquatic insect, and dormant bud of Pectinatella that belongs to Phylactolaemata. The diet of S. chankaensis tsuchigae was omnivorous, mainly vegetable feed on attached algae (filament form), and mainly animality feeded on benthic invertebrates such as Chironomidae larvae.