• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.3
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• pp.207-216
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• 2010

Individual differences of ozone ($O_3$) resistance for seed production, seed germination and seedling development were examined in this study. Five in each healthy and damaged trees of Pinus thunbergii growing in air polluted area for 12 years were chosen based on visible foliar injury and growth. The cones of P. thunbergii, which were collected from healthy and damaged trees, were analyzed for physical characteristics and seeds from the cones were used to test germination percentage under $O_3$ treatment. The germinated seeds were continuously exposed to $O_3$ treatment and the lipid peroxidation and activities of antioxidative enzymes were determined for both seeds and seedlings. The $O_3$ treatment for seed germination and seedling development were conducted at three conditions: control, 150 ppb and 300 ppb of $O_3$. The non-treated seeds from the damaged trees showed 21.6% lower germination than those from the healthy ones. On the $O_3$ treatment of 300 ppb, seed germination decreased approximately 10% for the healthy trees and 19% for the damaged trees compared to that on the control. The seeds from the healthy trees showed significantly higher activities of superoxide dismutase (SOD), glutathione reductase (GR), and catalase (CAT) than those from the damaged trees. The activities of GR, ascorbate peroxidase (APX), and CAT decreased along with the increasing $O_3$ concentration in two tree grades. Malondialdehyde (MDA) content of seeds was not influenced by $O_3$ treatment for two tree grades. In seedling development, there were no significant differences for length and biomass of needle and root of two tree grades at both the control and 150 ppb of $O_3$. At 300 ppb of $O_3$ treatment, however, the length and biomass of needle and stem decreased for two tree grades but no significant differences was detected in root. The seedlings from the damaged trees were more sensitive to the $O_3$ treatment, showing higher activities of SOD, APX, and CAT and content of MDA compared to those from the healthy tree seedlings. Our results indicate that seed germination and seedling development are vulnerable to increasing $O_3$ concentrations and that attention must be paid to the individual selection of tree species for reforestation.

• Journal of Animal Science and Technology
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• v.53 no.5
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• pp.481-487
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• 2011

Rearing density is a major factor in welfare production and health of broiler chicks. An experiment was conducted to investigate the effect of rearing density on the behavioral characteristics of Korean native chicks. In the study, 20, 30, and 40 chicks per pen (3.17 $m^2$) were used in each treatment and randomly allotted to 6.3 bird/$m^2$, 9.5 bird/$m^2$, and 12.6 bird/$m^2$ density, respectively. The broilers' behavior was recorded for 12 hours continuously during 1 to 8 weeks of age. The time budgets (standing, sitting, and walking) and frequencies of certain behaviors (drinking, feeding, preening, scratching, dust bathing, flapping, aggressive pecking, and pecking) in the broilers were checked during the day. The behavioral characteristics in the early period (1 to 4 weeks) were compared to the later period (5 to 8 weeks) to know the changes in each behavior as the chicks matured. It was observed that 40 chicks per pen showed significant decrease in feed intake and body weight. Corticosterone hormone was higher in the order of 12.6 bird/$m^2$ > 9.5 bird/$m^2$ > 6.3 bird/$m^2$ (p<0.05). The behaviors of standing and sitting were the highest in groups of 30 and 40 respectively. The walking behavior was gradually decreased as rearing density increased. The frequencies of the other behaviors also decreased in a high density treatment; especially for feeding, drinking, preening, and pecking. These tendencies widened the gaps of behaviors as time passed. It was concluded that a group of 20 chicks (6.3 bird/$m^2$) was the proper rearing density among these three treatments. Broilers in the lower rearing density showed more activity than that with higher density and therefore this environment may lead to better welfare condition.

• Journal of Animal Science and Technology
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• v.51 no.2
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• pp.143-154
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• 2009

(Y $\times$ L) $\times$ D-crossbred gilts and barrows weighing $80.2\pm0.2$ kg were fed a "medium-energy" (ME) or "low-energy" (LE) diet (3.2 vs 3.0 M cal DE/kg) and slaughtered at 110, 125, or 138 kg, after which physicochemical and sensory quality traits of major primal cuts of resulting carcasses were analyzed, under a 2 (sex) $\times$ 2 (diet) $\times$ 3 (slaughter weight; SW) factorial arrangement of treatments. The ADG and ADFI were greater (P<0.01) in barrows than in gilts and also in 125- and 138-kg vs 110-kg SW. Moreover, ADG and gain:feed were greater in ME vs LE (P<0.01), whereas ADFI was greater in LE vs ME (P<0.01). Backfat thickness, which increased with increasing SW (P<0.01), was not affected by sex or diet. Carcass marbling score was greater (P<0.01) in gilts and LE than in barrows and ME, respectively. Carcass quality grade, which was superior in LE vs ME, was not affected by SW, whereas the yield grade decreased abruptly between 125- and 138-kg SW primarily due to the upper limit of carcass weight imposed on the A and B grades. Physicochemical characteristics including pH, drip loss, and variables pertaining to color of belly, ham, and loin were not affected significantly by any of the treatment factors, albeit statistically significant in some cases, in terms of quality criteria. In sensory evaluation, the acceptability of fresh belly was not influenced by any of the treatment factors. Marbling score of fresh ham was greater in LE vs ME (P<0.01) and tended to increase between 110- and 125-kg SW (P=0.10); in loin, the increase of this variable between the two SW was significant (P<0.01). Following cooking, LE was superior to ME in the acceptability in belly and ham, but the effect of SW was insignificant in any of the sensory quality traits evaluated in this study in any of the three major primal cuts. In conclusion, the present results suggest that SW can be increased to up to 138 kg without compromising carcass quality and that LE has some beneficial effects on quality of the whole carcass and the major primal cuts.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.3
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• pp.274-279
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• 1989

The objective of the study was to determine optimum clipping time, interval and height of Suwon 1 pearl millet hybrid in Korea to increase forage yield and quality. Clipping height 20 cm above the ground surface was the best resulting in producing 11.1 tons per hectare of green chop. However, clipping height 5 cm was not good for regrowth of the ratoon crop. Just after the first cutting when the plant height reached two meters around mid-July, four weeks cutting interval was the best for higher forage yield of 11. 4 tons per hectare. Crude protein content of the clipping height 20 cm was the highest being 12.8 percent. Dry matter of the first cut contained 14 percent of crude protein being the highest, and with lower crude fiber content of 24 percent. And also four weeks cutting interval was the highest in crude protein content being 13.1 percent along with lower crude fiber content of 24.2 percent. Thus, the forage yield depended on clipping height greatly, but the quality was dependent upon clipping time, interval and frequency more than cutting height pearl millet plant. It would be desirable for higher yield and quality of Suwon 1 pearl millet hybrid to cut three or four times during the growing season at 20 cm clipping height and at four weeks clipping interval from the first cut when the canopy height is above one meter under the Korean environmental conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.149-157
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• 2018

In this study, we investigated the changes in physicochemical properties, antioxidant activities, and contents of functional compounds, such as avenanthramides (AVNs), vitamin E, and ${\beta}$-glucan, in oats by accelerated age-conditioning (temperature: $45^{\circ}C$, relative humidity: 20%). No significant differences were observed in crude protein, crude fat, and AVNs contents of three oat cultivars, up to 63 days of storage; however, their antioxidant activities, as well as ${\beta}$-glucan, vitamin E, and fatty acid contents were significantly different (p < 0.05). ${\beta}$-glucan and fatty acid contents and the antioxidant activities of Deayang (DY) cultivar did not change during storage. ${\beta}$-glucan and unsaturated fatty acid contents of Choyang (CY) and Jopung (JP) increased during the storage period, while antioxidant activities did not (DPPH-CY; 48.1 to 26.9 mg TEAC/100 g, JP; 49.4 to 26.7 mg TEAC/100 g. ABTS-CY; 88.4 to 56.3 mg TEAC/100 g, JP; 80.0 to 55.8 mg TEAC/100 g). The total vitamin E content in DY (1.20 to 0.85 mg/100 g) and CY (1.73 to 1.33 mg/100 g) decreased, but it was maintained in JP. This study indicated that the changes in physicochemical properties and functional compounds of oat grains during storage depends on the cultivars. The result showed that DY, which has the highest AVNs content, has more stable functional compounds and antioxidant activities during storage. These results can serve as essential data for post-harvest management and development of functional food materials for extending the use of oats.

• Economic and Environmental Geology
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• v.43 no.1
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• pp.1-12
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• 2010

Geochemical approaches on the two recovered piston cores were performed to understand the characteristics of organic matters and the influence of the sea level variation of the East Sea in the Hupo Basin since the Holocene. The analyzing results on organic components (TOC and TN), and isotopic compositions of organic matters showed the variation to core locations and sampling depths. In core 08HZP-01, their values were gradually changed with depth from 4 mbsf to seafloor. However, rapid variation was observed at the boundary of 4.71 mbsf (meter below seafloor) in core 08HZP-03. Based on TOC/TN, $\delta^{13}C_{org}$ and $\delta^{15}N_{org}$, the origin of organic matters in the Hupo Basin can be divided into three groups; 1) predominant marine algae, 2) $C_3$ land plant, and 3) mixture of $C_3$ land plant and marine/freshwater algae. It is likely that the vertical and spatial variations of organic and isotopic compositions reflect the shifts in sedimentary environment (including sediment transportation) by ocean currents and sea-level changes and others during the Holocene period.

• Economic and Environmental Geology
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• v.50 no.1
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• pp.1-14
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• 2017

The analytical conditions including surface state, moisture effect, and device condition were investigated for applying Short Wave Infrared(SWIR) spectroscopy to the field survey. Among the three surface state of samples (exposed surface, cutting face and powder), both spectra from the exposed surface and cutting face are almost identical whereas spectral variation was detected in powder sample. Over 24-hours-dryring of the wet sample at room temperature, the samples show a similar spectrum with that of dry condition. The result suggests that outcrop samples mighty be dried for 24 ~ 48 hours depending on the wetness of outcrop. The bright minerals could produce stable spectra with 10 times measurements as default value of the device under SWIR spectroscopy but the dark minerals would require about 10 seconds, which corresponds to 100 times measurements to get the reliable spectra. The position and shape 2,160 ~ 2,330 nm and/or other spectral features of hydrothermal alteration minerals by SWIR spectroscopy could be used for a classification of hydrothermal alteration zone in the field. Absorption peaks in 2,160 ~ 2180 nm are useful for identifying (advanced) argillic zone by spectral characteristics of kaoline, dickite, pyrophyllite, and alunite. Absorption peaks in 2,180 ~ 2,230 nm are able to define muscovite, sericite, and smectite, which are key alteration minerals in phyllic zone. Absorption peaks in 2,230 ~ 2,270 nm can be used to recognize prophylitic zone where chlorite and epidote occur. Absorption peaks of other principle minerals such as talc, serpentine, amphibole, and carbonate group are mainly detected within the wave length of 2,270 ~ 2,330 nm. This result indicates that the spectra of these minerals need to be carefully interpreted.

• Journal of Korean society of Dental Hygiene
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• v.7 no.4
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• pp.583-594
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• 2007

The purpose of this study was to conduct a survey on the senses that preliminary dental hygienists have on employment, who applied for the National Dental Hygienist Examination, so that it could provide a basic reference required for fostering good human resources specializing in oral health with a sense of mission and responsibility as professional. To meet these goals, a self-administered questionnaire survey was conducted for participants in a refresher education meeting for preliminary dental hygienists across three major regions(Seoul, Daejeon and Busan), which was held by the Korean Dental Hygienists Association(KDHA) on Jan. 15, 2006. Total 289 sheets of questionnaire were collected, and 262 sheets except invalid or incomplete ones were used for examination and analysis. As a result, this study came to the following conclusions: First, it was found that 40.4% respondents wanted to be employed in dental clinic or hospital. Most respondents(90.1%) answered that faithfulness is most valued as prerequisite qualification for employment in hospital, and highest percentage of respondents(39.3%) wanted to earn 16 to 17 million Korean won annually. For internship opportunities, 61.9% respondents replied that they could willingly accept the internship, provided that basic pay and switchover to regular employee are all assured. Second, as the results of survey on employment circumstances around respondents, it was found that most respondents(58.3%) were employed in dental clinic or hospital, and highest percentage of respondents(35.0%) earned 15 to 16 million Korean won. Third, it was found that interpersonal relationships among employees had most significant effects(4.81) on selection of employment, which was followed by in-house welfare benefits 1(monthly/annual vacation, resting room, etc; 4.56). For possible influential factors on the selection of employment depending on whether employed or not, it was found that there were Significant differences in pay, welfare benefit 2(seminar, orientation, refresher training opportunities, etc), post-wedding continued employment and merit system between employees and non-employees(pE0.05). Fourth, the survey on respondents' occupational senses of dental hygienist showed that major tasks of dental hygienists were represented by oral disease prevention(92.6%), case management(71.5%), oral health education(66.3%), hospital/clinic management and dental management support(10.4%) and public oral health activities(6.7%) respectively. For job satisfaction, it was found that almost half respondents(48.9%) showed satisfaction at their job and 32.6% felt satisfied at and proud of their job. That is, majority of respondents(81.5%) felt satisfied at their job as dental hygienist. For follow-up requirements to qualify for dental hygienists, it was found that 73.3% felt it necessary to give more investments to self-development, 62.2% respondents considered protection of membership's rights as one of future assignments that KDHA should be more committed to. For future social awareness about dental hygienists as occupation, 69.2% respondents expected that they would be better developed and treated as professional. And desired training courses as a part of qualification for professional dental hygienists were represented by case management(services, manners, etc; 33.3%), implant(28.9%), esthetics(correction, prosthesis, whitening; 18.9%) and so on. For an item on working years, it was noted that 75.9% respondents would keep working as dental hygienists as long as they could.

• Korean Journal of Environmental Agriculture
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• v.17 no.2
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• pp.174-181
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• 1998

In four citrus grow of Satsuma mandarin (rootstock of trifoliate orange) including two grove of organical management and two groves of conventional management, spores of arbuscular mycorrhizal(AM) fungi were identified and seasonal changes in spore density in soils and AM colonization of citrus roots were investigated. AM colonization in weeds found in the groves were also examined. Three species of Glomus (G.deserticola, G. vesiculiferum, G. rubiforme ) and one unknown species of Acaulospora were observed in all of the groves. Annual mean density of AM fungal spores were in the range of 10,000${\sim}$40,000 per 100g soil with more spores in the organically-managed groves. The least spores were observed in December in all groves, and the most spores in April in the organically-managed groves while in February or April in the conventionally- managed. Annual mean AM colonization more 27% of citrus root were observed in the organically-managed with the high peaks in April and October and the minimum in August, while mean colonization less than 15% in the conventionally-managed with the peak in February and the minimum in different times depending on groves and years. AM colonization corresponded to a sigmoidal curve consisting of a laf phase during winter and a subsequent increase in spring, then succeeded by a maximum, and then a decrease at the end of vegetation. Fungal spore density and AM colonization showed a parallel pattern during the sample period. The seasonality appeared to be related more to the phenology of the plant than to the soil factors. Generally more spore density and AM colonization were found in organically managed groves. AM colonization was not correlated with available P and organic matter content in soil in this field investigation. Among sixteen weed species found in the groves, Astrogalus sinicus of Leguminosae, Portulaca oleracea of Portulacaceae showed high colonization in all groves and they can be considered as a source of inoculumn and host plants for propagation of AM fungi.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.104-112
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• 2012

BACKGROUND: Agricultural inputs (fertilizer and organic inputs) and water conditions can influence $CH_4$ and $CO_2$ emission from agricultural soils. This study was conducted to investigate the effects of agricultural inputs (fertilizer and organic inputs) under changing water regime on $CH_4$ and $CO_2$ emission from a soil in a laboratory incubation experiment. METHODS AND RESULTS: Four treatments were laid out: control without input and three type of agricultural inputs ($(NH_4)_2SO_4$, AS; pig manure compost, PMC; hairy vetch, HV). Fertilizer and organic inputs were mixed with 25 g of soil at 2.75 mg N/25 g soil (equivalent to 110 kg N/ha) in a bottle with septum, and incubated for 60 days. During the first 30-days incubation, the soil was waterlogged (1 cm of water depth) by adding distilled water weekly, and on 30 days of incubation, excess water was discarded then incubated up to 60 days without addition of water. Based on the redox potential, water regime could be classified into wetting (1 to 30 days), transition (31 to 40 days), and drying periods (41 to 60 days). Across the entire period, $CH_4$ and $CO_2$ flux ranged from 0 to 13.8 mg $CH_4$/m/day and from 0.4~1.9 g $CO_2$/m/day, and both were relatively higher in the early wetting period and the boundary between transition and drying periods. During the entire period, % loss of C relative to the initial was highest in HV (16.4%) followed by AS (8.1%), PMC (7.5%), and control (5.4%), indicating readily decomposability of HV. Accordingly, both $CH_4$ and $CO_2$ fluxes were greatest in HV treatment. Meanwhile, the lower $CH_4$ flux in AS and PMC treatments than the control was ascribed to reduction in $CH_4$ generation due to the presence of oxidized compounds such as ${SO_4}^{2-}$, $Fe^{3+}$, $Mn^{4+}$, and ${NO_3}^-$ that compete with precursors of $CH_4$ for electrons. CONCLUSION: Green manure such as HV can replace synthetic fertilizer in terms of N input, however, it may increase $CH_4$ emission from soils. Therefore, co-application of green manure and livestock manure compost needs to be considered in order to achieve satisfactory N supply and to mitigate $CH_4$ and $CO_2$ emission.