• Journal of Life Science
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• v.23 no.5
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• pp.637-642
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• 2013

This study was performed to evaluate the rodent repellency and antimicrobial activity of natural oils. Thirteen natural essential oils were evaluated for repellent efficacy against rodent feed intake suppression activity. Salvia sclarea (sage), Cinnamomum zeylanicum (cinnamon) Cymbopogon citratus (lemon grass), and Syzygium aromaticum (clove) showed the best repellent efficacy among tested natural oils. Antimicrobial activity against Gram-negative (four strains) and Gram-positive (four strains) bacteria were evaluated using four natural oils, which showed high efficacy on the rodent repellent test. Syzygium aromaticum showed antimicrobial activity against all tested bacteria and Cymbopogon citratus, Cinnamonum zeylanicum, and Salvia sclarea showed antimicrobial activity against some tested bacteria.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.425-428
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• 2008

To use lightweight aggregate concrete with the structural material, it was need to evaluate property of mechanic and drying shrinkage and creep of the lightweight aggregate concrete, but these weren't. So the purpose of this study which it sees follows the mechanical property of the eco lightweight aggregate concrete according to the water binder ration in the high strength concrete. Eco lightweight aggregate was made with clay and crushed rock in this study. To make experiment, water binder ratio was divided 35% and 39%. And the fresh concrete properties were that slump flow was 500${\pm}$50mm, air contents was 2.0${\pm}$1.0%. It evaluated the hold a drying shrinkage and the creep the effect, it analyzed quality and reliability of the eco lightweight aggregate concrete.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.3
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• pp.667-675
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• 2014

Two types of diets, extruded pellet (EP) and raw-fish-based moist pellet (MP) were fed to compare growth, water quality and histology of olive flounder, Paralichthys olivaceus in Jeju fish farm. Two groups of 7000 fish per each tank (initial mean weight 51 g) were fed one of two diets for 7 months. At the end of the feeding trial, significant differences were found in weight gain and feed utilization. Dissolved oxygen (DO) level of the MP tank was decreased from 7.98 to 6.89 after feeding. There were no significant differences in hematocrit, hemoglobin, alanine aminotransferase and aspartate aminotransferase of fish fed the two diets. Whole body protein content of fish fed the EP was significantly higher than that of fish fed the MP. While the feeding rate by month indicated numerically decreased, fish fed the MP had higher feed intake than that of fish fed the EP. Histological examination of hepatopancreas, kidney, and anterior intestine of fish fed the EP did not show any negative effects compared to those of fish fed the MP. This study revealed that EP could substitute for MP in terms of growth performance, blood parameters, water quality and histology of olive flounder.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.433-440
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• 1999

Objective: To evaluate the effectiveness of CC+FSH or CC+hMG in intrauterine insemination (IUI) cycles for the treatment of infertility. Method: Patients received daily 100 mg of clomiphene citrate (CC) for 5 days followed by hMG or FSH. A single IUI was performed at 36 h after hCG. Clinical pregnancy was classified if a gestational sac or fetal cardiac activity was seen on ultrasound. Results: The overall clinical pregnancy rate was 19.1% per cycle (17/89) and 21.5% per patient (17/79). More clinical pregnancies were recorded in CC+FSH (23.1%, 6/26) than CC+ hMG cycles (17.5%, 11/63), but this difference was not statistically significant. No differences were found in age, duration of infertility, follicle size, levels of estradiol ($E_2$) on the day of hCG injection and total motile sperm counts between pregnant and non-pregnant groups. However, more ampules of gonadotropins were used in pregnant group than non-pregnant group (p<0.05). Conclusion: Combination of CC and hMG may economically be more effective to induce ovulation for IUI compared to CC and FSH.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.7
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• pp.1025-1032
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• 2013

The purpose of this study was to examine how socio-demographic characteristics and delinquent behaviors affect the suicidal ideation among the Korean high school students. Using the 35,668 senior high school student cases of 2009 Korean Youth Health Risk Behavior On-line Survey data, it conducted a secondary data analysis. Frequency analysis, chi-square test and logistic regression analysis was done. Being female, living without parents, low economic status, poor academic record, technical school students, young students, poor academic record, internet addition, problem drinking, smoking cigarettes and experience of drug use significantly increased probability of their suicidal thoughts. Findings may be used for tackle the issues of suicidal thoughts among the Korean senior high school students.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.132-136
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• 2002

The rice straw managements are essential for maintaining soil fertility as well as reducing chemical fertilizer application in paddy field. A field experiment was conducted on moderately well draining alluvial paddy soil to investigate the decomposition pattern of rice straw. The mesh bags containing the rice straw harvested in the previous year were placed at soil surface and buried into around 10cm depth and recovered periodically for determining the straw decomposition. Pot experiments were conducted to investigate the fates of N released from $^{15}$ N-labeled rice straw under different levels of N fertilizer application. The overall decomposition patterns of rice straw were similar for the two incorporation depths in transplanted paddy field. The straw incorporated at transplanting date showed weight loss of about 50%, 70% and 90% after 2 months, 5 months, and 2 years, respectively. The decompositions of straw cell wall components showed somewhat different pattern. The decompositions of cellulose and silica were similar to that of dry weight while the decomposition of lignin was slower than that of cellulose and silica. N was released from rice straw 42% and 65 % of the initial N after one month and after five months, respectively. P release was faster than N release. Recoveries of rice straw-$^{15}$ N by rice plants were 10.2, 13.4 and 14.9% in 0, 120 and 240 mg N pot$^{-1}$ , respectively. Soil recoveries of rice straw $^{15}$ N were 17.3, 20.6 and 18.9% in 0, 120 and 240mg N pot$^{-1}$ , respectively.

• Journal of Astronomy and Space Sciences
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• v.32 no.1
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• pp.73-80
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• 2015

The Yang-gyeong-gyu-il-ui (兩景揆日儀) is a kind of elevation sundial using three wooden plates. Sang-hyeok Lee (李尙爀, 1810~?) and Byeong-cheol Nam (南秉哲, 1817~1863) gave descriptions of this sundial and explained how to use it in their Gyu-il-go (揆日考) and Ui-gi-jip-seol (儀器輯說), respectively. According to Gyu-il-go (揆日考) there are two horizontal plates and two vertical plates that have lines of season and time. Subseasonal (節候) lines are engraved between seasonal (節氣) lines, subdividing the interval into three equal lines of Cho-hu (初候, early subseason), Jung-hu (中候, mid subseason) and Mal-hu (末候, late subseason); there are 13 seasonal lines for a year, thus resulting in 37 subseasonal lines; also, there are 12 double-hour (時辰) lines for a day engraved on these plates. The only remaining artifact of Yang-gyeong-gyu-il-ui was made in 1849 (the $15^{th}$ year of Heon-jong) and is kept at the Korea University Museum. We have compared and analyzed Yang-gyeong-gyu-il-ui and similar western sundials. Also, we have reviewed the scientific aspect of this artifact and built a replica. Yang-gyeong-gyu-il-ui is a new model enhanced from the miniaturization development in the early Joseon Dynasty and can be applied to the southern part of the tropic line through a structure change.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.222-222
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• 2007

RF circuit을 구현하는데 있어서 기판의 전기적 특성을 정확하게 아는 것은 원하는 결과를 추출하기 위해 매우 중요하다. 본 연구에서는 현재 사용되고 있는 PI 기판의 전기적인 특성인 유효 유전율과 loss tangent 값을 T-resonator률 이용해 정확하게 측정하고자 했다. T-resonator는 microstrip 구조로 구현 되었으며 conductor material은 Cu를 사용하였다. PI 기판의 두께는 25um, Cu의 두께는 PI 기판의 종류에 따라 12um 와 18um, T-resonator line width는 50um로 구현하였다. 또한 공진 주파수에 따라 stub 길이가 다른 10개의 T-resonator를 제작하였다. PI 기판의 유효 유전율을 구하기 위해 stub 길이의 open-end effect와 T-junction effect를 고려하였으며 수식을 통해 정확한 유효 유전률을 추출하였다. 또한 PI 기판의 loss tangent 추출에 필요한 dielectric loss를 추출하기 위해 unload quality factor를 분석하였다. Unload quality factor는 dielectric loss, conductor loss, radiation loss를 구성되며 conductor loss와 radiation loss를 수식에 의해 구하고 dielectric loss를 추출 하였다. 추출 된 dielectric loss를 통해 각각의 T-resonator의 loss tangent 값을 구하였다. T-resonator를 이용한 PI 기판의 측정은 비교적 복잡한 수식에 의해 이루어지지만 정확한 data를 얻을 수 있고 다른 재료의 전기적 특성을 추출하는데 응용이 가능하다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.210-210
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• 2007

RF circuit을 구현하는데 있어서 기판의 전기적 특성을 정확하게 아는 것은 매우 중요하다. 왜냐하면 초고주파로 갈수록 기판의 전기적인 특성이 circuit에 많은 영향을 미치고 이러한 영향을 고려한 circuit를 설계해야 원하는 결과를 얻을 수 있기 때문이다. 본 연구에서는 현재 사용되고 있는 PI 기판의 전기적인 특성인 유효 유전율과 loss tangent 값을 캐패시터를 이용해 정확하게 측정하고자 했다. 캐패시터의 conductor material은 Cu를 사용하였고 PI 기판의 투께는 25um 를 이용하였다. PI 기판의 유효 유전율은 캐패시터 측정에 의한 data률 EM simulation tool 을 통해 분석한 후 간단한 수식에 의해 구했다. 또한 PI 기판의 loss tangent 값을 구하기 위해 캐패시터의 dissipation factor를 분석하였다. 캐패시터의 dissipation factor는 dielectric loss, AC 저항에 의한 loss, DC 저항에 의한 loss를 포함한다, DC 저항에 의한 loss는 dissipation factor에 차지하는 비율이 낮기 때문에 생략이 가능하다. 하지만 AC 저항에 의한 loss는 주파수에 비례하여 값이 커지게 된다. 따라서 주파수가 올라 갈수록 dissipation factor도 상승하게 되는데 주파수의 전 대역에서 AC 저항에 의한 loss를 보정해주면 dielectric loss를 얻을 수 있다. 추출된 dielectric loss를 통해 PI 기판의 loss tangent 값을 구하였다. 캐패시터를 이용한 PI 기판의 전기적 특성 추출은 간단한 구조를 통해 얻을 수 있기 때문에 다른 재료의 기판의 전기적 특성을 추출하는데도 이용이 용이하다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.728-728
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• 2012

본 연구에서는 자연하상 복원을 위한 하상복원공법을 개발하여 시험구간에 적용하였다. 공법적용 대상 지역은 안양시역내의 안양천 일정구간으로 화창교로부터 상류방향으로 약 500m 거리에 웅덩이 수제공법이 적용되어 있으며, 그로부터 다시 상류방향으로 130m 떨어진 거리에 낮은 바닥막이 공법이 적용되어 있다. 낮은 바닥막이 공법의 경우 완만한 곡류사주의 직상류 부로서 강한 수류와 함께 빠른 유속이 형성될 경우 하상의 세굴이 예상되어 이를 방지하기 위해 저수로의 유하방향으로 완만한 호형으로 설치하였으며, 웅덩이형수제 공법은 완만한 곡류로 좌안 수충부가 형성되어 있어 물의 흐름방향과 유속을 제어하여 흐름에 의한 호안침식을 방지하기 위해 현 위치를 선정 및 적용하였다. 첫 번째, 경관모니터링 결과 낮은 바닥막이 공법과 웅덩이 수제 공법을 적용한 구간에서 대규모 홍수 이후에도 저수로 호안과 하상의 안정성이 유지되었으며, 이는 공법 설치 전 후 하상 경관의 변화가 거의 없어 수리적 안정성 유지를 하고 있다고 볼 수 있다. 또한 웅덩이 수제 공법 설치 후, 미소서식처가 형성되면서 포식자인 왜가리, 백로류를 지속적으로 관찰할 수 있어 어류서식처로서의 기능이 강화되었음을 간접적으로 확인하였다. 두 번째, 생태계 모니터링 결과 저서성 무척추동물의 경우 한국오수생물지수(KSI)는 낮은 바닥막이 공법을 적용하여 하상구조가 변화된 조사 지점 st.1의 환경상태가 "양호"에서 "최적"으로 변화하였기 때문에 공법 적용이 서식처 건강성 증진에 도움을 준 것으로 판단된다. 세 번째, 수질 모니터링 결과 용존산소의 경우 상부지점보다 하부지점이 낮게 나타나는 결과를 보여주었다. 낮은 바닥막이 공법에 의한 용존산소 상승효과보다는 다양한 서식처의 제공이라는 측면이 보다 중요한 효과를 나타낸다. 결과적으로, 공법의 실용화를 위한 적용 공법에 대한 생태계 모니터링 및 평가를 통하여 하천에서의 다양한 서식처(Habitat) 창출을 통해 수생 생물의 다양성을 증진시키고, 하천 하상공법에 대한 생태계의 조사 및 평가기법을 확보하여 연구성과를 다른 하천으로의 확대 적용 할 수 있을 것으로 기대한다.