• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.399-402
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• 2004

착탈식의 플라스틱 디스크와 부상형 광헤드를 사용하는 광드라이브에서 부상형 광헤드의 부상안정성 문제는 고밀도 표면기록의 신뢰성 확보를 위해 매우 중요한 요소로 고려되어야 한다. 플라스틱 디스크와 광헤드의 포커싱 제어를 위해 부상형광헤드의 광학적 조립오차와 플라스틱디스크의 보호층의 오차를 보상해주는 추가적인 엑츄에이터의 몇 가지 설계방안에 대해 검토한다. 또한 본 논문에서는 부상형 광헤드의 부상안정성을 위하여 디스크의 굴곡에 대한 부상특성과 안정성을 해석하고, 특히 로드/언로드 시의 부상안정성에 대해서도 검토해 본다.

• 한국식품과학회지
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• 제32권5호
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• pp.979-984
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• 2000

열풍건조양파의 품질을 향상시키기 위해서 갈변억제제를 선발하였고, 갈변억제제가 갈변도, 환원당, pyruvic acid및 vitamin C의 함량에 미치는 영향을 조사하였다. 절단한 양파는 $70^{\circ}C$에서 5시간 열풍건조 하였고 수분함량은 3% 이내였다. 여러 가지 갈변억제제중 cyclodextrin과 corn starch를 갈변억제제로 선발하여 처리한 결과 4% 전분현탁액에 침지한 양파가 다른 처리구에 비교하여 갈변억제효과가 뛰어났고, 색의 변화와 갈변도는 상관성이 있었다. 갈변억제제를 처리한 건조 양파들은 대조군과 비교할 때 갈변을 약 $24{\sim}32%$ 억제하였다. 대조구에 대한 처리구의 갈변억제율은 물에 침지한 것은 16%, 0.5% cyclodextrin 처리구는 24%, 4% corn starch 처리구는 32%로 비교적 크게 나타났다. 처리에 따른 건조양파의 성분중 pyruvic acid는 약 $15{\sim}26%$만이 잔존되어 크게 감소되었으나 환원당 및 vitamin C 함량은 비교적 변화가 적었다.

• 대한금속재료학회지
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• 제48권4호
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• pp.335-341
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• 2010

High-quality single-walled carbon nanotubes (SWCNTs) were synthesized by catalytic decomposition of $C_2H_2$ using Fe-Mo/MgO catalyst at $800^{\circ}C$. The as-synthesized SWCNTs typically occurred in the form of a bundle with a diameter of 10~20 nm together with amorphous carbon and catalytic impurities, which were removed by a two-step purification process consisting of oxidation and an acid treatment. The oxidation step, using an $O_2$-Ar mixture at $380^{\circ}C$ for 5 hr in a vertical-type furnace and a $HNO_3$ treatment at $100^{\circ}C$ for one hour, was utilized to remove the amorphous carbon particles. Subsequently, metallic catalysts were removed in HCl at room temperature for 5 hr under magnetic stirring. The SWCNT suspension was prepared by dispersing the purified SWCNTs in an aqueous sodium dodecyl benzene sulfonate solution with horn-type sonication. This was then air-sprayed on glass to fabricate CNT field emitters. The samples had a turn-on field value of 4 V/${\mu}m$ and a current density of 0.67 mA/$cm^2$ at 9 V/${\mu}m$. Increasing the HCl treatment time improved the field emission properties.

• 한국표면공학회지
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• 제57권1호
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• pp.22-30
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• 2024

This study reports a direct growth of carbon nanotubes (CNTs) on the surface of LiCoO₂ (LCO) powders to apply as highly efficient cathode materials in lithium-ion batteries (LIB). The CNT synthesis was performed using a thermal chemical vapor deposition apparatus with temperatures from 575 to 625 ℃. Ferritin molecules as growth catalyst of CNTs were mixed in deionized (DI) water with various concentrations from 0.05 to 1.0 mg/mL. Then, the LCO powders was dissolved in the ferritin solution at a ratio of 1g/mL. To obtain catalytic iron nanoparticles on the LCO surface, the LCO-ferritin suspension was dropped in silicon dioxide substrates and calcined under air at 550℃. Subsequently, the direct growth of CNTs on LCO powders was performed using a mixture of acetylene (10 sccm) and hydrogen (100 sccm) for 10 min. The growth behavior was characterized by scanning and transmission electron microscopy, Raman scattering spectroscopy, X-ray diffraction, and thermogravimetric analysis. The optimized condition yielding high structural quality and amount of CNTs was 600 ℃ and 0.5 mg/mL. The obtained materials will be developed as cathode materials in LIB.

• 한국축산시설환경학회지
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• 제14권1호
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• pp.31-38
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• 2008

자연환기식 육성 비육돈사의 내부 사육환경을 개선하고자 돈사내부에 악취탈취장치를 설치하였다. 악취탈취장치에서 탈취한 공기는 덕트를 이용하여 돈사내부에 분배되도록 하였다. 악취탈취장치의 가동에 따른 내부의 환경은 돈사의 측벽에 설치된 윈치커튼을 닫아 관리하기 때문에 내부의 환경이 열악해지는 겨울철에 실시하였다. 악취탈취장치를 가동하면서 분석한 돈사의 내부환경 개선효과는 다음과 같다. 1. 돈사내부에 설치한 악취탈취장치에서 탈취된 후 배출된 공기를 돈사내부에 재분배함으로써 악취탈취장치 가동전보다 돈사내부의 암모니아 가스 농도를 약 33.3% 줄일 수 있는 것으로 나타났다. 2. 돈사의 암모니아 가스 저감효과는 돈사의 환기율이 $0.5m^3/m$ 두 이하인 경우에 나타났으며, 환기율이 많아지면 외부의 신선한 공기의 유입에 의해 희석되는 양이 악취탈취 장치에서 배출된 공기량보다 많아 악취탈취 장치 가동에 의한 내부 환경개선 효과는 작은 것으로 나타났다. 3. 육성 비육돈사에 악취탈취장치를 가동하면서 돼지를 입식하여 출하 때까지 사육한 결과 악취탈취장치 설치전과 비교하여 돼지의 폐사율이 약 3.8% 줄어들었으며, 탈취장치 가동후 돈사내부에 관리를 위해 들어갈 때 눈 따가움, 부유먼지 등이 크게 줄어든 것으로 나타났다.

• Tuberculosis and Respiratory Diseases
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• 제60권6호
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• pp.663-672
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• 2006

연구배경: 미세먼지는 여러 가지 유기물과 무기물의 복합체로 그 구성 성분이 시간과 장소에 따라 다르고 모양과 크기도 일정하지 않으며, 특히 지름 $10{\mu}m$이하의 미세먼지 (particulate matter 10; $PM_{10}$)는 흡입이 가능한 입자의 크기여서 하부기관지 및 폐의 가스-교환부분까지 침착하여 호흡기계에 손상을 일으킬 수 있다. 본 연구에서는 황사에 포함된 $PM_{10}$과 비황사 시기에 포집된 $PM_{10}$이 폐상피세포주에 작용하여 전염증성 사이토카인(proinflammatory cytokine) 및 cytokine messenger RNA(mRNA)의 발현에 어떤 영향이 있는지를 관찰하여 기관지 천식과 만성 폐쇄성 폐질환등 호흡기 질환의 증상 악화기전에 미치는 역할을 규명하고자 하였다. 연구방법: 공기 포집기(HV 500F, sibata model)를 이용하여 황사와 비황사 기간에 하루 6시간씩 실외의 장소에서 대기분진을 membrane filter에 포집한 다음, $PM_{10}$입자를 추출하고 폐암 상피세포주인 A549 cells(한국세포은행주)에 $PM_{10}$을 농도에 맞게($10{\mu}g/ml$, $100{\mu}g/ml$, $500{\mu}g/ml$) 노출시켰다. 각각의 노출된 세포로부터 interleukin(IL)-$1{\alpha}$, $IL-1{\beta}$, IL-8, granulocyte macrophage colony stimulating factor(GM-CSF)의 mRNA를 역전사중합효소연쇄반응(reverse transcriptase polymerase chain reaction; RT-PCR) 방법으로 측정하였다. 결 과: 황사 및 비황사 기간 중 포집된 $PM_{10}$을 가했을 시 가하지 않은 대조군에 비하여 $IL-1{\alpha}$, $IL-1{\beta}$, IL-8, granulocyte macrophage colony stimulating factor (GM-CSF)의 m'RNA와 cytokine의 발현이 유의하게 높았으며, 황사 기간의 고농도의 $PM_{10}$에 노출된 세포의 $IL-1{\alpha}$ mRNA는 비황사 기간의 $PM_{10}$에 노출된 세포의 mRNA보다 증가되어 있었다. 결 론: $PM_{10}$은 A549 cells에서 전염증성 사이토카인의 발현을 증가시키고 비황사 기간보다 황사 기간 중 대기 중에서 채취한 $PM_{10}$에 노출된 A549 cells에서 일부의 전염증성 사이토카인의 mRNA발현을 더욱 증가시키는 것을 알 수 있었다. 따라서 황사 기간의 $PM_{10}$에 의한 일부의 전염증성 사이토카인의 발현 증가가 만성 호흡기 질환의 증상 악화기전에 연관되어 있을 가능성을 시사하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제16권12호
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• pp.1738-1742
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• 2003

The whole plant of crop maize was chopped and ensiled in double-layered polyethylene bags to determine the influence of residual sugar on the fermentation of lactic acid and aerobic stability by L. buchneri in whole crop maize silage made in airstress condition. There were a total of six treatments used in this experiment as follow: added 25 g de-mineralised water per kg chopped maize serving as control (con), 37.5 g glucose solution containing 12.5 g glucose ($g_1$), 75 g glucose solution containing 25 g glucose ($g_2$), 25 g, L,.buchneri suspension intended for $10^6$ cfu $g^{-1}$ (L.b.), $g_1$+L.b. and $g_2$+L.b. All silos were opened at day 91 after ensiling for measuring the pH values, microbiological enumeration, fermentative products and aerobic stability. The dry matter loss increased significantly (p<0.01) due to inclusion of sugar or L. buchneri. The lower lactic acid concentrations were observed (p<0.01) in silages inoculated with L. buchneri only or in combination with sugar addition than the correspondent uninoculated silages. Compared with control silage, ethanol production was about 3 or 6-fold higher due to addition 12.5 or 25 g glucose per kg chopped maize at ensiling. The silages added with sugar contained less acetic acid concentration (p<0.01) than control, but silages inoculated with L. buchneri showed the contrary effects (p<0.01) at different sugar levels. No butyric acid was found in uninoculated silages, silages inoculated with L. buchneri. producted more propionic acid, 1-propanol and butyric acid. Lactic acid bacteria counts increased markedly (p<0.01) due to inoculation with L. buchneri, whereas it was reduced (p<0.01) by added sugar. No significant difference was observed in count of yeast, but inoculation with L. buchneri shows a decreasing trend. Mould count in all silages was less than 2 (log cfu $g^{-1}$). The added sugar had negative effects on aerobic stability of maize silage made under air-stress conditions, whereas inoculation with L. buchneri improves (p<0.01) the aerobic stability.

• 한국구조물진단유지관리공학회 논문집
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• 제24권3호
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• pp.57-62
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• 2020

국내에 설치된 하수관거 중에서 20년을 초과한 콘크리트관의 연장은 66,334km로서 전체의 42.5%를 차지한다. 열화된 콘크리트 하수관거에서는 내부 하수의 유출로 인해 관로 주변의 동공을 확장시켜 땅꺼짐 등의 문제도 발생시키기 때문에 이에 대한 보수를 통한 유지관리가 필요한 실정이다. 본 연구에서는 초속경시멘트 및 분리저감제를 적용한 수중불분리성 모르타르를 하수관거 보수에 적용하기 위한 기초연구를 수행하였다. 배합조건에 따른 응결시험 결과 분리저감제 혼입에 따라 종결이 최대 172%정도 지연되는 것으로 나타났다. 수중분리도는 분리저감제 0.3% 이상 혼입시 pH 12 이하로 측정되었고, 현탁액량은 분리저감제 0.2% 이상 혼입시 50mg/l이하로 측정되어 국내 KCI-AD102 기준을 만족하였다. 기건조건과 수중조건에서 타설하였을 때의 강도비 평가 결과, 분리저감제 혼입시 80% 이상의 강도비를 나타내어 국내 KCI-AD102 기준을 만족하였다. 부착강도는 분리저감제 혼입시 기건조건보다 수중조건에서 타설하였을 때 높은 강도로 측정되었다. 내수성 검토는 분리저감제 혼입량에 따른 흡수율과 투수성으로 평가하였고, 각각 42.6%, 36.6%의 성능개선을 확인하였다.

• Asian Journal of Atmospheric Environment
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• 제7권2호
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• pp.65-71
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• 2013

Japanese cedar (Cryptomeria japonica) pollinosis is the most popular pollinosis in Japan. It has been reported that Cryptomeria japonica pollen allergenic species are suspended as fine particles in the urban atmosphere. These allergenic fine particles are responsible for inducing asthma by breaking into the lower respiratory tract. It has also been found that pollinosis symptoms on the sufferers appear mainly at night-time by the results from epidemiological studies. However, the exact reason for these phenomena is not yet clarified. In this study, the diurnal and nocturnal behaviours of Cryptomeria japonica pollen grains and their allergenic species in the urban area of Saitama city of Kanto Plain were investigated. Airborne pollen grains and allergenic Cry j 1 concentrations in total suspended particulate matter (TSP) were investigated at two sampling sites, a heavy traffic road (roadside site) and at the balcony of the $10^{th}$ floor of the Building of Research and Project of Saitama University (general urban site). The latter sampling site where located about 300 m away from the roadside site was used as a general urban site unaffected by automobile traffic. The airborne pollen counts were measured with a real-time pollen monitor. Cry j 1 particles were collected with two high volume air samplers, and these concentrations were measured by surface plasmon resonance method with a Biacore J system. The diurnal variation of the airborne pollen counts was similar to the trends of temperature and wind speed during the day-time; whereas its tendency with wind speed trend was not observed during the night-time. Airborne pollen counts were lower with northern wind than with southern wind because the pollen comes from the mountainous areas, and the mountains in the south are closer, about half the distance to the northern mountains. It is suggested that the peaks of airborne pollen counts during night-time in the sampling site occurred by transport of pollen grains released during day-time in the mountainous forest areas, located c.a. 100 km away from the sampling site. On the roadside site the allergenic Cry j 1 concentrations were higher than at the general urban site, nevertheless pollen grains counts were lower. These results suggested that worsening of pollinosis symptoms during night-time in urban area was caused by transport of pollen grains during day-time in the mountainous forest areas. Moreover, pollen allergenic species become different morphology from pollen grain at roadside site, and the subsequent pollen grains re-suspension by automobile traffic.

• 한국가축번식학회지
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• 제14권1호
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• pp.1-8
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• 1990

These experiments were carried out to investigate the effects of cumulus cells for in vitro fertilization and development of bovine follicular oocytes matured in vitro. The bovine ovaries were obtained at a slaughter house and the follicular oocytes surrounded by cumulus cells were collected by puncturing follicles with 2~6 mm of diameter. Bovine oocytes were matured in vitro for 24~26 hours in a CO2 incubator with 5% CO2 in air at 39$^{\circ}C$. The medium used for maturation was TCM-199 supplemented with hormones, pyruvate, FCS and antibiotics. Epididymal spermatozoa were capacitated by in vitro culture for 2~3 hours in BO solution containing BSA(5mg/ml) and caffeine(2.5mM). Insemination was made by introducing about 10~15 matured oocytes into the suspension of capacitated spermatozoa. Six hour after insemination the eggs were transferred to TCM-199 supplemented with FCS(10%) and HEPES(25mM), cultured for 7~8 days with 10~15 eggs/well in 4-well multidishes(Nunc Co.) forming cumulus cell monolayer. The results obtained in these experiments were summarized as follows ; 1. The majority of the follicular oocytes with compacted cumulus cells existed in GV stage while those with dispersed or denuded cumulus cells existed GVBD and M II stage. 2. After 24~26 hours maturation, the maturation rates of the follicular oocytes cultured in TCM-199 containing hormones were slightly higher than those of oocytes cultured in medium without hormones, and the frequency of cumulus compacted or denuded oocytes reaching M II stage cultured in medium containing hormones was 75.7% or 51.7%, respectively(P<0.05). 3. After 20 hours in vitro insemination, percentages of ova fertilized were 61.4% or 51.4%, respectively, for cumulus oophorus intacted or removed, and increased frequency of ova with both male and female pronuclei was found when cumuli were present(P<0.05). 4. The rates of embryos developed to 2-, 4-, 8-, 16-cell and morula or blastocyst stage after cocultured with cumulus cells were 65.0%, 45.3%, 34.7%, 28.0% and 22.7%, respectively. The results for momla or blastocyst stage were significantly higher than those of the embryos cultured in the basic medium(P<0.05).