• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.237-246
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• 2008

Filtration rates and fecal production of freshwater bivalve, Unio douglasiae on two kinds of hibernal diatom communities were measured simultaneously in a laboratory. One community is the Han River (HAN), which dominated by Asterionella Formosa. Stephanodiscus hantzschii (ca. 98% of total phytoplankton). The other community is the Ilgam Lake (IL), which dominated by Synedra ulna, Scenedesmus sp. Microcystis aeruginosa (ca. 82%). The HAN water has higher concentrations of nutrient (TN and TP) and chlorophyll $\alpha$ (Chl-$\alpha$), lower turbidity and conductivity than the IL water. Water sampling for the feeding experiment was conducted in the same day (Jan 15, 2008) and similar time (AM 10:00 for HAN, AM 11:00 for IL). Mussels with the similar size ($0.0{\pm}0.5\;cm$) were collected from the Gunsan and Okgu district (Jeonbuk), and starved in a laboratory for 2 days before the experiment. The experiment comprised CON (no addition of mussel), LOW (addition of mussel at 0.3 indiv. $L^{-1}$), MID (1.0 indiv. $L^{-1}$) and HIGH (2.0 indiv. $L^{-1}$), respectively. With the increment of mussel density and time, the concentration of Chl-$\alpha$ in two diatom communities were clearly decreased; Chl-$\alpha$ of HAN gradually decreased after 1 hour of mussel treatment, while that of IL decreased as soon as mussel introduction. In 7 hours of treatment, the former was removed finally up to about 90% of control, while the later was remained as about 50%. Under the presence of mussel, total phytoplankton density was shifted as the similar patterns to that of Chl-$\alpha$ (r=0.705, P<0.0001), however, there showed the drastic differences following a species. Based on the concentration of Chl-$\alpha$, filtration rate of U. douglasiae averaged 0.266 $L\;g^{-1}\;h^{-1}$ (0.115 to 0.442) on HAN and $0.577\;L\;g^{-1}\;h^{-1}$ (0.146 to 1.428) on IL water, respectively. There were no differences in feces production among the mussel density in the HAH water (ANOVA, P>0.5), while in IL water, including lots of seston, the HIGH mussel produced the higher fecal materials, over one hundred times of LOW. These results suggest that freshwater bivalve Unio douglasiae have the alternative potential, as a filter-feeder of seston in turbid lake, and a biological controller of diatom bloom in cold stream.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.57-69
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• 2017

Overwintering and succession of phytoplankton community with physicochemical and biological characteristics were investigated in pilot culture system. Water and phytoplankton samples were collected twice a week from February 23 to June 28, 2016. A total of 17 overwintering taxa including cyanophyceae, chlorophyceae, bacillariophyceae were identified in the experimental group in winter (February), and these overwintering species showed a marked succession pattern along with environment changes. In the process of phytoplankton succession, a total of 56 species in 28 genera were identified in two (experimental, control) pilot culture system. In the experimental group, 52 phytoplankton species in 24 genera were identified, and the number of taxa was highest in chlorophyceae (35 species), followed by Bacillariophyceae (9 species), Cyanophyceae (5 species) and others (3 species). In the control group, 25 phytoplankton species in 14 genera were classified and these taxa consisted of 17 chlorophyceae, 3 cyanophyceae, 2 Bacillariophyceae and 3 others. The standing crops ranged from 40 to $325,450cells\;mL^{-1}$ in the experimental group, and from 900 to $37,100cells\;mL^{-1}$ in the control group, respectively. The dominant species were represented by Monoraphidium minutum, Microcystis aeruginosa, Rhodomonas lacustris, Ankyra judai and Chlorella vulgaris in the experimental group; and M. minutum and Coenochloris cf. pyrenoidosa in the control group. In conclusion, overwintering and succession of predominant phytoplankton species developed due to interactions of internal environmental factors(physicochemical and biological factors) in the pilot culture system.

• Journal of The Korean Society of Grassland and Forage Science
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• v.29 no.1
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• pp.37-42
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• 2009

This experiment was conducted to investigate the effect of cattle manure application on macro contents change in pasture. The treatment consisted of T1: 100% chemical fertilizer (CF 100%), T2: 50% CF+50% cattle manure (CM), T3: 25% CF+75% CM, T4: 100% CM 100%, T5: 100% CM(1st year (yr.) +100% CF (2nd yr.)+100% CM (3rd yr.), T6: 100% CM (1st yr.)+100% CF (2nd yr.)+100% CF (3rd yr.). The highest substitution effect of chemical fertilizer with cattle manure indicated by the highest yield of 11,169 kg/ha was obtained from the application of 100% CM (1 yr.) + 100% CF (2 yr.). The forage yield of plots applied with 100% CM (1 yr.) + 100% CF(2 yr.) was only 4% more than the yield of plots applied with 100% CM. It was only 3% less than the yield of plots applied with 100% CF. In this study, cattle manure application recorded slightly lower forage dry matter (DM) yield than 100% CF application but they were statistically comparable on the third year of production. The all treatments have narrow range of P, K, Ca, Mg and Na contents $0.25{\sim}0.32%,\;3.08{\sim}3.71%,\;0.42{\sim}0.55%,\;0.21{\sim}0.38%$ and $0.08{\sim}0.15%$.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.2
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• pp.87-93
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• 2014

Multiple cropping system is an important agricultural system in Korea, which is significant to increase forage yield and promote agricultural economic development. This experiment was carried out to develop triple cropping systems (winter cereals crop for forage - silage corn - summer oats) for maximum year-around forage production at paddy field in southern region. We also to select a winter forage crop to determine corn planting time, and to examine the forage productivity and feed value of summer cultivated oat, which was planted after corn cultivation. When winter cereal crops for forages are harvested in accordance with and corn planter, the fresh yield and dry matter yield of rye were 32.0 ton/ha and 5.8 ton/ha, respectively, showing higher yielding compared to other winter crops. Corn silage as summer crop was showed the fresh yield and dry matter yield of 72.1 ton/ha and 20.2 ton/ha, respectively. In the feed value, crude protein and TDN contents were 7.4% and 69.3%, respectively. They was showed higher productivity and feed value. The heading date of High-speed oat was October 10, and its fresh yield and dry matter yield were 37.6 ton/ha and 8.0 ton/ha, respectively. As a feed value, crude protein and TDN content was 11.4% and 59.1%, respectively. Therefore, triple cropping systems for the production of forage all throughout the year are possible with the introduction of summer oats in the southern region, and rye could be the most suitable winter forage crops for triple cropping systems.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.87-93
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• 2013

'Okhan' (Avena sativa L.), an oat cultivar for winter use, was developed by the breeding team at the Department of Rice and Winter Cereal Crop, NICS, RDA in 2011. It was derived from an original cross between 'Early80', exhibiting early heading, and 'Maine PI-590' (CI 7518), exhibiting large-size grain, in 1995. Subsequent generations as well as cross-bred cultivars were handled in bulk, and pedigree selection programs took place at Suwon and Yeoncheon, respectively. A promising line, 'SO95027-B-45-16-10-6-2-Y7-10', was selected in 2004, and was designated 'Gwiri74' after being selected from a yield trial for three years from 2005 to 2008. The breeding line 'Gwiri74' was subsequently evaluated for earliness of heading and forage yield in four different locations, Yesan, Iksan, Kimjae, and Jeju, from 2009 to 2011, and was finally named as 'Okhan'. Over 3 years, the heading date of 'Okhan' was about 6 days earlier than that of the check cultivar 'Samhan', and their average forage dry matter yield harvested at the milk-ripe stage was 15.0 ton $ha^{-1}$, compared with 14.1 ton $ha^{-1}$ of check cultivar. Cultivar 'Okhan' was lower than the check cultivar 'Samhan' in terms of the protein content (9.2% and 9.9%, respectively) and total digestible nutrients (58.5%, and 59.3%, respectively), while the TDN yield per ha was more than the check (8.70 and 8.36 kg, respectively). Fall sowing cropping of 'Okhan' is recommended only in areas where average daily minimum mean temperatures in January are higher than $-7^{\circ}C$, and it should not be cultivated in mountain areas, where frost damage is likely to occur.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.4
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• pp.264-270
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• 2017

This study was carried out to investigate the optimal harvesting time, feed value and fermentation quality of barley and wheat for the making of chopped whole crop silage substitute for formula feed. As a result, the moisture content of barley and wheat decreased with a late harvest, and barley progressed faster than wheat. The plant height was similar with harvesting time, and the number of spikes decreased with prolonged period after heading. The dry matter yield and TDN yield of barley harvested at 35 and 40 days after heading were significantly higher than those at 30 days after heading and wheat was significantly higher at 40 and 45 days than at 35 day after heading(p<0.05). Crude protein content of barley and wheat were increased with later harvesting time, and crude fiber, crude fat and crude ash were slightly decreased, but not statistically significant. NDF and ADF content of barley decreased with later harvesting time, and those showed similar level in wheat. TDN content of barely was slightly increased but there was no difference in wheat. Comparing the effects of fermentation on feed value of chopped whole crop silage, the approximate compositions were slightly increased after fermentation, but the difference was not significant. Fermentations resulted in increasing the pH value of barley silage with late harvesting time, but decreasing the lactic acid content(p<0.05). A pH value of wheat silage showed similar level in different harvest time, and lactic acid content was decreased. Considering the quantity and quality of fermentation, barley and wheat can be used for making chopped silage of whole crop silage when they were harvested at 35 days and 40~45 days after heading, respectively.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.50-55
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• 2010

This study was conducted to investigate the shelf-life and quality of breads made with 0.5, 1 and 2% of Myagropsis myagroides fermented ethanol extracts (MOE). The total microbial count in breads made with 2% MOE decreased to about 1.6 log cycles as compared to that of breads not containing MOE. The protection index measured by rancimat increased with an increase in the quantity of MOE in the breads. During the storage period, the pH value was not different between breads containing MOE and breads not containing MOE. The lightness and redness of the breads decreased with an increase in the quantity of MOE, while the yellowness increased. In the sensory evaluation, the breads containing 0.5% MOE were more preferred than the breads not containing MOE. These results suggest that the addition of 0.5% MOE to breads has a good effect on improving the shelf-life and overall quality.

• Korean Journal of Food Science and Technology
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• v.46 no.6
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• pp.750-756
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• 2014

This study was performed to understand the effect of cultivation periods on the physicochemical characteristics of the starch of five sweetpotato cultivars, cultivated in Muan, Korea. Starch, protein, and ash contents increased with increased cultivation period, whereas amylose content decreased. Rapid viscosity analysis showed that the pasting temperature, peak viscosity, breakdown, setback and final viscosity increased with increased cultivation period. However, trough and final viscosity decreased. Although the onset temperature and peak temperature values increased, the conclusion temperature did not show any consistent patterns by differential scanning calorimetry. X-ray diffraction showed that the starch samples had C-type crystallinity irrespective of the cultivation period and cultivar. The starch granules were dominantly round and oval, or polygonal irrespective the cultivation period. The bigger the particle size was, the longer the cultivation period was.

• Korean Journal of Head & Neck Oncology
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• v.14 no.2
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• pp.244-252
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• 1998

The thyroid nodules are the most common endocrine disease requiring surgical management. We perfomed a clinical study of 298 cases with thyroid nodules, who were admitted to and operated at the Department of Surgery, College of Medicine, Gyeong sang National University from January 1987 to April 1997 and the results were summarized as follows: 1) Patients were composed of 214 cases(71.8%) of benign nodule and 84 cases(28.2%) of malignant nodule. Benign and malignant nodules were prevalent in fifth decade. 2) The sex distribution showed a preponderance of females with ratio of 5.88:1 in benign nodule and 11:1 in malignant nodule. 3) The nodules were located in the right lobe(134 cases, 44.9%), the left lobe(121 cases, 40.6%), both lobes(34 cases, 11.4%), and isthmus(8 cases, 2.7%). The possibility of malignancy was higher in the solid rather than cystic lesions. 4) Radioactive iodine scintiscans were perfomed in 273 cases and revealed cold nodules in 237 cases(86.8%), 58 of these cases(24.4%) were malignant. 5) According to the histopathologic classification, benign nodules included follicular adenomas 136 cases(63.5%), adenomatous goiters 67 cases(31.3%), Hurthle cell adenomas 4 cases(1.9%), cysts 3 cases(1.4%) and thyroiditis 4 cases(1.4%). In malignant nodules, papillary carcinomas 72 cases(85.7%), follicular carcinoma 8 cases(9.5%), undifferentiated carcinoma 2 cases(2.4%), medullary carcinoma 1 case(1.2%) and malignant lymphoma 1 case(1.2%). 6) The most commonly performed operative procedure was a lobectomy with isthmusectomy(85.5%) for bengn nodules and a total thyroidectomy(51.2%) for malignant nodules. 7) The rate of complications was higher in the cases with malignant nodules(20.2%) than in the benign cases(0.5%). The recurrence rate was 8.3%(7 cases).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.135-135
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• 2018

천이금속 질화물 코팅은 우수한 기계적 특성들로 인해 공구 코팅으로 많이 사용 되어왔다. 그 중에서도 특히 Cr계 경질 코팅은 높은 경도와 낮은 표면조도, 우수한 마찰특성 등 뛰어난 기계적 특성을 나타내므로 공구 코팅으로의 적용 가능성이 크다. 그러나 최근 공구산업의 발전으로 인해 공구가 더욱 가혹한 환경에서 사용됨에 따라, 공구의 수명을 향상시키고 보호하기 위해 코팅의 높은 밀착력이 요구되고 있으며, 모재와 코팅 사이에 중간층을 합성함으로써 공구의 밀착력을 향상시키는 연구가 활발히 진행되고 있다. 이전 연구에서 모재/중간층/코팅간의 경도와 탄성계수 비율(H/E ratio)의 구배가 코팅의 밀착력에 큰 영향을 미치는 것으로 확인되었다. 그러므로, WC 모재와 Cr계 코팅의 중간값의 H/E ratio를 갖는 중간층의 합성을 통해 코팅의 밀착력을 향상시킬 수 있을 것으로 판단된다. 본 연구에서는, 코팅의 밀착력을 향상시키기 위해 다양한 중간층을 증착한 CrZrN, CrAlN 코팅을 비대칭 마그네트론 스퍼터링 장비를 이용하여 합성하였다. 모재로는 디스크 형상의 WC-6wt.%Co 시편을 사용하였고 Cr, Zr, Si, Al single 타겟을 이용하여 Cr, CrN, CrZrN, CrZrSiN 등의 중간층이 증착된 코팅을 합성했다. 코팅의 합금상, 경도 및 탄성계수, 미세조직 및 조성, 표면 조도을 확인하기 위해 X-ray diffractometer (XRD), Fischer scope, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy를 사용하였고, 코팅의 밀착 특성을 분석하기 위해 scratch tester와 optical microscopy (OM)를 이용하였다. 코팅의 내열성을 확인하기 위해 코팅을 furnace에 넣어 공기중에서 500, 600, 700, 800, 900, $1,000^{\circ}C$로 30분 동안 annealing 한 후에 nano-indentation을 사용하여 경도를 측정하였다. CrZrN 및 CrAlN 코팅을 나노 인덴테이션으로 분석한 결과, 모든 코팅의 경도(33.4-35.8 GPa)와 탄성계수(384.1-391.4 GPa)는 중간층의 종류에 상관없이 비슷한 값을 보인 것으로 확인됐다. 그러나, 코팅의 마찰계수는 중간층의 종류에 따라 다른 값을 보였다. CrZrN 코팅의 경우 CrN 합금상 중간층을 갖을 때 가장 낮은 값을 보였으며, CrAlN 코팅의 경우 CrN/CrZrSiN 중간층을 증착하였을때 마찰계수는 0.34로 CrZrN 중간층을 증착하였을 때(0.41)에 비해 낮은 값을 보였다. 또한, 코팅의 마모율 및 마모폭도 비슷한 경향을 보인 것으로 보아, CrN/CrZrSiN 중간층을 합성한 CrAlN 코팅의 내마모성이 상대적으로 우수한 것으로 판단된다. 코팅의 밀착력의 경우도 마찰계수와 비슷한 경향을 보였다. 이것은 중간층의 H/E ratio가 코팅의 내마모성에 미치는 영향에 의한 결과로 사료된다. H/E ratio는 파단시의 최대 탄성 변형율로써, 모재/중간층/코팅의 H/E ratio 구배에 따라 코팅 내의 응력의 완화 정도가 변하게 된다. WC 모재 (H/E=0.040)와 CrAlN 코팅(H/E=0.089) 사이에서 CrN, CrZrSiN 중간층의 H/E ratio는 각각 0.076, 0.083으로 모재/중간층/코팅의 H/E ratio 구배가 점차 증가함을 확인 할 수 있었고, 일정 응력이 지속적으로 가해지면서 진행되는 마모시험중에 CrN과 CrZrSiN 중간층이 WC와 CrAlN 코팅 사이에서 코팅 내부의 응력구배를 완화시키는 역할을 함으로써 CrAlN 코팅의 내마모성이 향상된 것으로 판단된다. 모든 코팅을 열처리 후 경도 분석 결과, CrN/CrZrSiN 중간층을 증착한 CrAlN 코팅은 $1,000^{\circ}C$까지 약 28GPa의 높은 경도를 유지한 것으로 확인 되었고, 이는 CrZrSiN 중간층 내에 존재하는 SiNx 비정질상의 우수한 내산화성에 의한 결과로 판단된다.