• 한국자동차공학회논문집
• /
• 제23권4호
• /
• pp.410-419
• /
• 2015

In this study, the roadability, fuel economy and emission characteristics were evaluated for a natural gas converted vehicle. The results are as follows; Not only the shortage of power was observed in stall test, but also large deterioration of acceleration performance was exposed in roadability. Compared to the original LPG system, the acceleration is 76% in start acceleration and 45 ~ 65% in overtaking acceleration, especially the decline became larger when air conditioner is at work. Furthermore, because the mapping data, which controls the injection depending on driving condition, do not match up with injection system, the failure of air-fuel ratio feedback control occurs resulting from the large gap between the required and the really supplied amount of fuel. This failure cause the exhaust gas to emit without catalytic conversion and the fuel economy based on the fuel heat value to get worse 22% in the mode test and 16% in road test respectively. In addition, the existing injection system does not secure enough fuel at the starting so that it may lead to the fail of clod start, the deterioration of hot start and inharmonic of engine at the idle after start.

• 식품보건융합연구
• /
• 제6권1호
• /
• pp.9-15
• /
• 2020

Salinity with sodic condition disturbs germination, retards emergence, and slow down seedling development of Lemon Grass (Cymbopogon citratus).Lemongrass is a perennial grass plant widely distributed worldwide and most especially in tropical and subtropical countries. This research experiment was designed to evaluate the influences of (4 dSm^-1+ 13.5 (mmol L^-1)^-1/2, 5 dSm^-1+ 25 (mmol L^-1)^1/2, 5 dSm^-1+ 30 (mmol L^-1)^1/2, 10 dSm^-1+ 25 (mmol L^-1)^1/2 and 10 dSm^-1+ 30 (mmol L^-1)^1/2) on biomass produce of lemon grass against salt tolerance. The uppermost biomass yield (45.53 gpot^-1) was produced by 4 dSm^-1+ 13.5 (mmol L^-1)^1/2 treatment. The increase in the intensity of salts reduced the growth of lemon grass. Lower biomass yield (79.33 gpot^-1) was gained at 10 dSm^-1+ 30 (mmol L^-1)^1/2. 5 dSm^-1+ 25 (mmol L^-1)^1/2 treatment performed enhanced outcome i.e. the least reduction % over control (5.87). Salinity- sodicity showed serious effect on the growth reduction from 5.87% to33.60%. This reduction gap was affected by the negative effect of salinity and sodicity on Linseed growth. Salinity- sodicity showed severe impact on the growth reduction from 5.87% to33.60%. Based on the findings, lemon Grass (Cymbopogon citratus).was capable to grow up the maximum at 4 dSm^-1+ 13.5 (mmol L^-1)^1/2 treatment.

• 한국식품과학회지
• /
• 제16권1호
• /
• pp.11-16
• /
• 1984

멥쌀 및 찹쌀 전분을 상압과 가압가열 및 알칼리 호화한 회석전분 호화액에 대해 유동특성을 검토하였다. 전분농도 $0.2{\sim}1.0%$의 저농도의 호화전분액은 지수법칙 유체의 유동거동을 나타내었으며 아밀로오스 함량에 따라 크게 좌우되어 아밀로오스 함량이 많은 멥쌀은 점성이 낮고 뉴우톤 유체의 경향을 나타내었으며 농도에 대한 영향이 작았다. 찹쌀 전분은 농도가 증가함에 따라 의가소성 성질이 강해졌으며 농도에 따라 급격히 점도가 증가하였다. 가압호화시킨 경우 찹쌀 전분 호화액의 점조도 지수 및 유동 거동 지수는 상압 호화액에 비하여 거의 변화가 없었으나 멥쌀 전분 호화액의 점조도 지수값은 현저히 증가하는 현상을 보였다. 가압 가열호화 및 알칼리 호화 용액은 상압 가열호화에 비해 훨씬 높은 점성을 보였다. 가열 호화 및 알칼리호화액의 겉보기 점도에 대한 온도의 영향을 검토해 본 결과 아레니우스식의 형태에 따름을 알 수 있었다.

• KIEAE Journal
• /
• 제11권3호
• /
• pp.57-62
• /
• 2011

Asbestos have been used around the world because of reliable and cost-effective physicochemical characteristics. After incubation period about 15-40 years asbestos can cause various cancers, including malignant mesothelioma when inhaled into the air. These properties turned out, asbestos have been banned from using in developed countries. Also in Korea also, the use of asbestos was banned across the board by revision of Industry Safety and Health Act in February 2009. Therefore, the problem of asbestos is not when using. It is about dismantling, maintenance, and the final processing of asbestos waste. Asbestos Cement slates which is Widely distributed throughout the country as roofing materials has much scattering potential compare with inside materials. Also Ministry of Environment is planning to introduce legislation 'Asbestos Safety Management Act' through Environment Announcement and The same Act. 24 show as follows. Minister of Environment or governor should do survey on the actual condition targeting rural buildings with slates and partly or fully fund to dissolve, remove asbestos slate which was used in each buildings. Therefore, to solve these problems, database-building and necessity of management strategies have been continually arisen. So this study was performed. Its application value is very high in terms of its political, economic. Asbestos Cement Slates database could build to collect national registered building data and then using GIS, asbestos cement Slates distribution map were constructed in each province's cities and counties of the country. And this map by Application, construction was to visualize by application, construction of year. Through these results, information of Asbestos Cement Slates could visually inform to policy makers, asbestos dismantling and management contractor, and civilian and it would alleviate the gap of knowledge information. This is expected to be utilized by medium and long-term and effective plan for demolition and dismantling of asbestos cement Slates.

• 한국세라믹학회지
• /
• 제41권1호
• /
• pp.57-61
• /
• 2004

Zinc Oxide (ZnO)은 wurtzite 결정구조를 가지고 있으며, 밴드갭 에너지가 약 3.3eV로 반도성 산화물이다. $In_2O_3$이 첨가된 ZnO 박막을 점자빔증착법을 이용하여 1737F 유리기판에 제조하였다. $400^{\circ}C$의 증착온도에서 $In_2O_3$의 첨가량에 따른 ZnO 박막의 결정성, 미세구조를 비롯한 전기.광학적 특성을 조사하였다. 첨가되는 $In_2O_3$의 양에 따라 투명전도성 산화막으로써의 ZnO 박막의 특성이 변화되었다. $In_2O_3$의 첨가량이 감소할수록 비정질상에서 결정성의 ZnO 막을 얻을 수 있었다. 0.2at%의 $In_2O_3$가 첨가된 출발물질에서 제조된 $In_2O_3$-doped ZnO막은 약 $6.0 {\times} 10^{-3} {\Omega}cm$ 정도의 비저항값과 가시광선 영역에서 85% 이상의 광투과도를 나타내었다.

• Transactions on Electrical and Electronic Materials
• /
• 제8권6호
• /
• pp.241-245
• /
• 2007

[ $(Ba_{0.9-x}Sr_xCa_{0.10})TiO_3$ ] (x=0.33, 0.36) powders were prepared by sol-gel method. $(Ba,Sr,Ca)TiO_3$(BSCT) thick films, undoped and doped with $MnCO_3$ and $Yb_2O_3(0.1{\sim}0.7mol%)$, were fabricated by the screen printing method on the alumina substrate. The coating and drying procedure was repeated 6-times. The Pt bottom electrode was screen printing method on the alumina substrate. These BSCT thick films were annealed at $1420^{\circ}C$ for 2 hr in atmosphere. The upper electrodes were fabricated by screen printing the Ag paste and then firing at $590^{\circ}C$ for 10 min. And then the structured and dielectric properties as a function of the doping amount of $Yb_2O_3$ were studied. As a result of the TG-DTA, exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films showed XRD patterns of typical cubic peroveskite structure. The average thickness of BSCT thick films was about $70^{\mu}m$. The curie temperature and the dielectric constant decreased with increasing $Yb_2O_3$ doped content and the relative dielectric constant of the specimen, doped with 0.5 mol% $Yb_2O_3$ at BSCT(54/36/10), showed a best value of 5018 at curie temperature.

• 약학회지
• /
• 제41권1호
• /
• pp.38-47
• /
• 1997

Using a concentric cylinder type, rheometer. the steady shear flow properties of vaseline were measured over the temperature range of 20~70${\circ}$C. In this paper, the shea rate and temperature dependencies of its flow behavior were investigated and the validity of some flow models was examined. In addition, the flow characteristics over a wide temperature range were quantitatively evaluated by calculating the various material parameters. Main findings obtained from this study can be summarized as follows: (1) At relatively lower temperature range, vaseline is a plastic fluid with a yield stress and its flow behavior shows shear-thinning characteristics. (2) As the temperature increases, the value of a yield stress and the degree of shear-thinning become smaller, consequently, the Newtonian flow behavior occurs at a lower shear rate range. (3) At temperature range lower than 45${\circ}$C, the flow behavior shows much stronger temperature dependence, and a larger activation energy is needed for flow. (4) The Herschel-Bulkley model is the most effective one g$^3$ to predict the flow behavior of vaseline having a yield stress. The validity of the Bingham and Casson models becomes more available with increasing temperature. The flow behavior of vaseline at temperature range higher than 45${\circ}$C can be perfectly described by the Newton model.

• Bulletin of the Korean Chemical Society
• /
• 제35권10호
• /
• pp.3052-3058
• /
• 2014

In this article, we have designed and synthesized a novel donor-${\pi}$-acceptor (D-${\pi}$-A) type porphyrin-based sensitizer (denoted UI-5), in which a carboxyl anchoring group and a 9,9-dimethyl fluorene were introduced at the meso-positions of porphyrin ring via phenylethynyl and ethynyl bridging units, respectively. Long alkoxy chains in ortho-positions of the phenyls were supposed to reduce the degree of dye aggregation, which tends to affect electron injection yield in a photovoltaic cell. The cyclic voltammetry was employed to determine the band gap of UI-5 to be 1.41 eV based on the HOMO and LUMO energy levels, which were estimated by the onset oxidation and reduction potentials. The incident monochromatic photon-to-current conversion efficiency of the UI-5 DSSC assembled with double-layer (20 nm-sized $TiO_2$/400 nm-sized $TiO_2$) film electrodes appeared lower upon overall ranges of the excitation wavelengths, but exhibited a higher value over the NIR ranges (${\lambda}$ = 650-700 nm) compared to the common reference sensitizer N719. The UI-5-sensitized cell yielded a relatively poor device performance with an overall conversion efficiency of 0.74% with a short circuit photocurrent density of $3.05mA/cm^2$, an open circuit voltage of 0.54 mV and a fill factor of 0.44 under the standard global air mass (AM 1.5) solar conditions. However, our report about the synthesis and the photovoltaic characteristics of a porphyrin-based sensitizer in a D-${\pi}$-A structure demonstrated a significant complex relationship between the sensitizer structure and the cell performance.

• 청정기술
• /
• 제14권4호
• /
• pp.256-264
• /
• 2008

본 연구에서는 생분해가 가능하여 친환경성이 우수한 지방족 폴리에스터 중에서 PBAST를 이용하여, 다중유화법($W_1/O/W_2$)에 의해 PBAST/PVA 두층을 갖는 중공미세구를 제조하였다. 최적의 이중층 중공미세구를 얻을 수 있는 조건은, 유기상에서 의 PBAST고분자의 농도 5 wt%, 내부 수용액 상에서의 PVA의 농도 5 wt%, $W_1/O$ emulsion과 외부 수용액상의 비율이 1:4.5이었고 계면활성제는 단일 성분을 사용하는 경우보다 HLB 값의 차이가 큰 보조계면활성제(co-surfactant)를 사용하는 경우였으며, 이때 PBAST/PVA 이중층중공미세구(double-layered microsphere)의 제조 수율은 30.92%, 미세구의 총괄밀도(bulk density)는 0.180 g/ml이며 입자크기는 $1.5{\sim}3\;{\mu}m$로 고른 분포를 나타내었다.

• 한국재료학회지
• /
• 제15권8호
• /
• pp.491-495
• /
• 2005

(Zn,Mg)O (ZMO) thin films doped with Ga $(0\~0.03mol\%)$ in the target source were prepared by pulsed laser deposition on c-plane sapphire substrates at $500^{\circ}C$, and the effect of Ga contents on the properties of the electrical, optical and crystal properties of the deposited films was investigated. From X-ray diffraction patterns, ZMO film doped with $0.02 mol\%$ Ga showed crystal structure with c-axis preferred orientation, showing only the (0002) and (0004) diffraction peaks. In contrast, ZMO film doped with $Ga=0.03 mol\%$ showed a randomly oriented crystal structure. All the samples were highly transparent, showing the transmittance values of above $85\%$ in the visible region. For all the Ga doped ZMO films, the value of energy band gap was found to be about 3.5 eV, regardless of their Ga contents. From the Hall measurements, the resistivity and the carrier density for the ZMO film doped with $0.01 mol\%$ Ga were about $5\times10^{-4}\Omega-cm$ and $2\times10^{21}cm^{-3}$, respectively.