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        검색결과 443

        161.
        2016.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Gas hydrate desalination process is based on a liquid to solid (Gas Hydrate, GH) phase change followed by a physical process to separate the GH from the remaining salty water. The GH based desalination process show 60.5-90% of salt rejection, post treatment like reverse osmosis (RO) process is needed to finally meet the product water quality. In this study, the energy consumption of the GH and RO hybrid system was investigated. The energy consumption of the GH process is based on the cooling and heating of seawater and the heat of GH formation reaction while RO energy consumption is calculated using the product of pressure and flow rate of high pressure pumps used in the process. The relation between minimum energy consumption of RO process and RO recovery depending on GH salt rejection, and (2) energy consumption of electric based GH process can be calculated from the simulation. As a result, energy consumption of GH-RO hybrid system and conventional seawater RO process (with/without enregy recovery device) is compared. Since the energy consumption of GH process is too high, other solution used seawater heat and heat exchanger instead of electric energy is suggested.
        4,200원
        163.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to evaluate a visual surveillance system. The advancement of recording technology and network service make it easy to record and transfer the videos. Moreover, progressed recognition technology help to make a distinction each other. Cows show distinguishing behaviors during their estrus period. The mounting is one of the behaviors. The result was different depending on the breed of the cows and the size of the farm. In the case of Korean native cattle, the estrus detection rate was 71.15%, however, dairy cows, the estrus detection rate was 39.38%. At the farms having below 6 modules, the estrus detection rate was 87.41%. On the other hand, at the farms having over 6 modules, the estrus detection rate was 77.78%. With the proper progress, the visual surveillance system can be used to detect heat detection.
        4,000원
        164.
        2016.05 구독 인증기관·개인회원 무료
        일반적인 MBR공법의 경우 허용한계 이상의 고농도 MLSS에서 운영되면 막오염이 급격히 발생된다. 이는 슬러지 케익 축적이 원인이며 이로 인해 분리막 회복을 위한 빈번한 세정이 적용되어야 하고 그 결과 운영비 증가 및 분리막 수 명이 단축된다. 본 연구에서는 (주)에코니티의 자유말단형(End-Free) 분리막을 이용한 MBR 시스템 운전을 진행하였다. 분리막 모듈의 구조적인 특성으로 슬러지가 쉽게 탈리되어 케익의 축적이 발생하지 않아 고농도 MLSS에서도 적용가능함을 확인 하였다. 이에 따라 운전 플럭스를 상향시킬 수 있었고 장기 운전을 통하여 막여과 시스템의 안정운영을 평가하였다.
        165.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to improve seismic safety of nuclear power plant (NPP) structures in high seismicity area, seismic isolation system can be adapted. In this study, friction pendulum system (FPS) is used as the seismic isolation system. According to Coulomb‘s friction theory, friction coefficient is constant regardless of bearing pressure and sliding velocity. However, friction coefficient under actual situation can be changed according to bearing pressure, sliding velocity and temperature. Seismic responses of friction pendulum system with constant friction and various velocity-dependent friction are compared. The velocity-dependent friction coefficients of FPS are varied between lowand fast-velocity friction coefficients according to sliding velocity. From the results of seismic analysis of FPS with various cases of friction coefficient, it can be observed that the yield force of FPS becomes larger as the fast-velocity friction coefficient becomes larger. Also, the displacement response of FPS becomes smaller as the fast-velocity coefficient becomes larger.
        4,000원
        166.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. Use the El Centro seismic(1940, NS) analysis was performed. Analysis results, on the top floor displacement response to the earthquake response, did not have a big effect. However, acceleration response control effect was found to be excellent. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.
        4,000원
        167.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Deseeded jujubes are commonly consumed as snacks. This study was conducted to develop a seed-removing machine for jujubes that relieves hard work in manual seed removal. The seed-removing machine consists of a jujube supplying unit, a punching unit, and a discharging unit. To test the performance of the machine, shape characteristics, seed removing rate, sarcocarp cracking rate, and flesh hardness were analyzed throughout the jujube storage period. The machine showed good seed removing and sarcocarp cracking rates at room temperature and cold temperature storage on days 2, 15, and 50. Seed removing rates were 80% at day 15 and 96% at day 50. The sarcocarp cracking rates were 33% for day 15 and 30% for day 50. Hardness started to decrease from day 8 to day 70 at both room temperature and cold temperature storage. The working capacity of the machine was 900 fruits/h. The results showed that the jujube seed removing machine is useful for reducing the labor requirements of postharvest jujube processing.
        4,000원
        168.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aerodynamic performance of solar wing system has been evaluated through wind tunnel test. The test model has 12 panels, each supported by 2 cables. The panels were installed horizontally flat, and gaps between panels were set constant. Sag ratios of 2% and 5%, and wind directions between 0° and 90° were considered. Mass of test model was determined considering the mass of full scale model, and Froude number and Elastic parameter were satisfied by adjusting the mean wind speed. From the wind tunnel test, it was found that the aerodynamic performance of the solar wing system is very dependent on the wind directions and sag ratios. When the sag was 2%, the fluctuating displacements between the wind directions of 0° and 30° increase proportionally to the square of the mean wind speed, implying buffeting-like vibration and a sudden increase in fluctuating displacement was found at large mean wind speed for the wind directions larger than 40°. When the wind direction was larger than 60°, a sudden increase was found both at low and large mean wind speed. When the sag ratio is 5%, distribution of mean displacements is different from that of sag ratio of 2%, and the fluctuating displacements show very different trend from that of sag ratio of 2%.
        4,000원
        169.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study primarily focused on evaluating the performance characteristics of 4.75-mm nominal maximum aggregate size (NMAS) asphalt mixtures for their more effective implementation to a layered flexible pavement system. METHODS: The full-scale pavements in the FDOT’s accelerated pavement testing (APT) program, including 4.75-mm mixtures at the top with different thicknesses and asphalt binder types, were considered for the faster and more realistic evaluation of the rutting performance. The results of superpave indirect tensile (IDT) tests and hot-mix asphalt fracture mechanics (HMA-FM) based model predictions were used for cracking performance assessments. RESULTS: The results indicated that the rutting performance of pavement structures with 4.75-mm mixtures may not be as good as to those with the typical 12.5-mm mixtures, and pavement rutting was primarily confined to the top layer of 4.75-mm mixtures. This was likely due to the relatively higher mixture instability and lower shear resistance compared to 12.5-mm mixtures. The energy ratio (ER) and HMA-FM based model performance prediction results showed a potential benefit of 4.75-mm mixtures in enhanced cracking resistance. CONCLUSIONS : In relation to their implementation, the best use of 4.75-mm mixtures seem to be as a surface course for low-trafficvolume applications. These mixtures can also be properly used as a preservation treatment that does not necessarily last as long as 12.5-mm NMAS structural mixes. It is recommended that adequate thicknesses and binder types be considered for the proper application of a 4.75-mm mixture in asphalt pavements to effectively resist both rutting and cracking.
        4,000원
        170.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, by comparing the heating performance when operating the air conditioning system that is installed directly air-cooled(heater) air conditioning central air conditioning system of the ship, with improved performance, through the actual measurement study of thermal environment of the cabin, Ship's air conditioning in the future it is intended to be used as a basic data experience of design and planning.
        4,000원
        171.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Damped outrigger systems have been proposed as a novel energy dissipation system to protect tall buildings from severe earthquakes and strong wind loads. In this study, semi-active damping devices such as magnetorheological (MR) dampers instead of passive dampers are installed vertically between the outrigger and perimeter columns to achieve large and adaptable energy dissipation. Control performance of semi-active outrigger damper system mainly depends on the control algorithm. Fuzzy logic control algorithm was used to generate command voltage sent to MR damper. Genetic algorithm was used to optimize the fuzzy logic controller. An artificial earthquake load was generated for numerical simulation. A simplified numerical model of damped outrigger system was developed. Based on numerical analyses, it has been shown that the semi-active damped outrigger system can effectively reduce both displacement and acceleration responses of the tall building in comparison with a passive outrigger damper system.
        4,000원
        172.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES: The purpose of this thesis is to evaluate the effectiveness of an active noise cancellation (ANC) system in reducing the traffic noise level against frequencies from the predictive model developed by previous research. The predictive model is based on ISO 9613-2 standards using the Noble close proximity (NCPX) method and the pass-by method. This means that the use of these standards is a powerful tool for analyzing the traffic noise level because of the strengths of these methods. Traffic noise analysis was performed based on digital signal processing (DSP) for detecting traffic noise with the pass-by method at the test site. METHODS : There are several analysis methods, which are generally divided into three different types, available to evaluate traffic noise predictive models. The first method uses the classification standard of 12 vehicle types. The second method is based on a standard of four vehicle types. The third method is founded on 5 types of vehicles, which are different from the types used by the second method. This means that the second method not only consolidates 12 vehicle types into only four types, but also that the results of the noise analysis of the total traffic volume are reflected in a comparison analysis of the three types of methods. The constant percent bandwidth (CPB) analysis was used to identify the properties of different frequencies in the frequency analysis. A-weighting was applied to the DSP and to the transformation process from analog to digital signal. The root mean squared error (RMSE) was applied to compare and evaluate the predictive model results of the three analysis methods. RESULTS: The result derived from the third method, based on the classification standard of 5 vehicle types, shows the smallest values of RMSE and max and min error. However, it does not have the reduction properties of a predictive model. To evaluate the predictive model of an ANC system, a reduction analysis of the total sound pressure level (TSPL), dB(A), was conducted. As a result, the analysis based on the third method has the smallest value of RMSE and max error. The effect of traffic noise reduction was the greatest value of the types of analysis in this research. CONCLUSIONS : From the results of the error analysis, the application method for categorizing vehicle types related to the 12-vehicle classification based on previous research is appropriate to the ANC system. However, the performance of a predictive model on an ANC system is up to a value of traffic noise reduction. By the same token, the most appropriate method that influences the maximum reduction effect is found in the third method of traffic analysis. This method has a value of traffic noise reduction of 31.28 dB(A). In conclusion, research for detecting the friction noise between a tire and the road surface for the 12 vehicle types needs to be conducted to authentically demonstrate an ANC system in the Republic of Korea.
        4,000원
        174.
        2015.11 구독 인증기관 무료, 개인회원 유료
        When using the original Angio Intervention, one had to put Guide wire, Catheter on patient's leg so that there were curves according to patients and the possibility of patients moving made it inconvenient to proceed. Thus, by making supplementary tool shaped of table, it minimized the inconvenience of patients and operator, increasing the convenience of the process and thereby evaluating the utility and its usefulness. The main material of supplementary tool was used with cost efficient Fomax material, and by considering the patient's lower limb, and the length of tools when doing Angio Intervention, it was made as 1300mm, 600mm at the front, 500mm at the back. Also, considering the weight of the tool, it was manufactured with thickness of 5mm and 10mm with the same design, and evaluated by using survey of 14 medical personnel using the tool in A University Hospital, Daejeon. When manufacturing and using supplementary tool, it became heavier as the thickness increased. Whereas, the thinner, the lighter the tools were, however, had unstability which cause lack of safety. Despite the fact, they responded that they had more convenience of using 5mm and 10mm tool compared to when they did not have at all, and through this, we could evaluate that the use of supplementary tool is useful to the procedure. Accordingly, when doing Angio Intervention, we could find out that it is useful to use the supplementary tools, and by reducing the weight and increasing the safety, if we can make use of this kind of supplementary tools, it would be more useful to the procedure.
        4,000원
        175.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        대형녹조류인 Ulva pertusa는 전 세계 연안에 서식하는 저서성 종으로 대발생 또는 인공구조물에 착생되어 경제적, 사회적인 측면에서 문제를 야기시키고 있다. 착생생물을 제어하기 위해 신방오제인 ziram, diruon, zinc pyrithione (ZnPT), copper pyrithione(CuPT), DBNPA, triclosan 등이 방오도료로 사용 중이나, 대형 및 미세조류를 이용한 신방오 제들의 방오능 검증과 기초적인 연구자료가 부족한 실정이다. 따라서 본 연구에서는 초기 우점착생종인 구멍갈파래의 포자를 이용하여 방오제의 효능을 검증하고 생체막 형성의 우점종인 미세조류 Nitzschia pungens를 이용한 방오능을 검증하였다. 구멍갈파래포자의 운동성 검증에서 ziram과 ZnPT는 diuron, CuPT, DBNPA, triclosan보다 50% 높은 운동성 억제를 나타내었고 착생 검증에서는 ziram이 가장 낮은 착생률 1%로 나타났으며 CuPT는 100 ㎍/L의 농도에서 다른 대조군에 비해 80%의 성장율 억제를 보였다. 본 연구의 결과로 신방오제의 방오능을 검증하여 향후 방오능 검증에 기초자료가 될 것으로 사료된다.
        4,000원
        177.
        2015.09 구독 인증기관 무료, 개인회원 유료
        Regarding therapies for treatment of corneal wounds, ex vivo corneal culture is the most effective for minimizing expensive animal studies. Eighteen porcine enucleated eyes were soaked in 0.2% povidone iodine solution for disinfection prior to cornea excision. Subsequently, corneas were excised from whole eyes and filled with an agar/medium mixture. Corneas were transferred into culture dishes, after which culture medium was added until the limbus was covered. Cultures were then placed onto a plate rocker to mimic blinking action, followed by incubation at 37°C and 5% CO2. Corneas were harvested on Days 0, 3, and 7 after incubation, and optical coherence tomography (OCT) was performed on Day 7. Two eyes from each group were fixed in 2% glutaraldehyde/4% paraformaldehyde for low-vacuum scanning electron microscopy (LV-SEM), and four eyes from each group were fixed in 10% neutral-buffered formalin for histological analysis. OCT results showed that central corneal thickness significantly increased by Day 7 compared to Day 0 (P<0.05). Using LV-SEM, gaps between endothelial cells were detected on Day 7 of ex vivo culture. In the histological evaluation, four to five stratified squamous cell layers, wing cells, and basal cells in the epithelium as well as flat-shaped keratocytes in the stroma were found on Day 0. By Day 7, stratified squamous cells and basal cells had decreased in number, and slightly round-shaped keratocytes were observed; however, the number of keratocytes was similar to that on Day 0. In this short-term ex vivo culture, epithelium and endothelium were sensitive to culture, whereas stroma and keratocytes were well maintained. An additional deswelling method will be needed to obtain more successful results in porcine corneal ex vivo culture.
        4,000원
        178.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Vibrio 속에 속한 세균에 의한 식중독은 오염된 해산물식품의 섭취로 인하여 빈번하게 발생하고 있다. 그러므로 해산물을 날것으로 섭취하는 한국인의 특성을 고려할 때, 빠르고 정확한 Vibrio 검출기술은 식품위생 및 공중보건의 측면에서 매우 중요하다. 이와 관련하여 본 연구에서는 전통적인 배지를 이용한 동정방법의 단점을 보완할 수 있는 생화학적 방법인 Vitek 2 system방법과 분자생물학적 방법인 species-specific PCR 방법을 사용하여 얻은 동정결과를 비교·평가하고자 하였다. 본 연구에서는 5개의 Vibrio 표준균주와 16S rRNA gene sequencing 결과에 의하여 Vibrio 속으로 확인된 24개의 분리균주가 이용되었다. Vitek 2 system방법을 이용한 경우, 이와 같이 본 연구에 사용된 29개 균주 중 Vibrio 표준균주 2개(2/5, 40%), 16S rRNAgene sequencing 결과 Vibrio 속으로 확인된 분리균주 15개(15/24, 62.5%) 등의 총 17개 균주(17/29, 58.6%)가 Vibrio 종으로 동정되었다. 그리고 species-specific PCR방법을 이용한 경우, 위의 29개 균주 중 Vibrio 표준균주 5개(5/5, 100%), 16S rRNA gene sequencing 결과 Vibrio 속으로 확인된 분리균주 16개(16/24, 66.7%) 등의 총 21개 균주(21/29, 72.5%)가 Vibrio 종으로 동정되었다. Vitek 2 system방법과 species-specific PCR방법을 이용하여 동정된 결과를 비교하였을 때 표준균주 중 V. parahaemolyticus, V. mimicus등의 2개(2/5, 40%), 새우분리균주 24개 중에서 16S rRNAgene sequencing 결과 Vibrio 속으로 확인된 분리균주 7개(7/24, 29.2%) 등의 총 9개(9/29, 31%) 균주들에 대한 동정결과만이 일치하였다.
        4,000원
        179.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. An artificial wind of 1000 seconds with 0.1 second time steps was generated by using a Kaimal spectrum. Analysis results show that outrigger damper system is more effective up to 20-23% in the control of dynamic response compared to conventional outrigger system. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.
        4,000원
        180.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It has been widely accepted that the pressure management of water distribution systems using pressure reducing valves(PRVs) would be an effective method for controlling leakages. A pressure reducing valve (PRV) regulates outlet pressure regardless of fluctuating flow and varying inlet pressure, thereby reducing leakage and mitigating the stress on the water distribution system. However, the operation of a PRV is vulnerable to its mechanical condition and hydraulic operability. In this research, the effect of PRVs installed in water distribution system are evaluated in terms of hydraulic pressure reduction and mechanical performance by analyzing measured pressure data with statistical approach. A statistical approach using the moving average filter and frequency analysis based on fourier transform is presented to detect abnormally operated PRVs that have been densely installed in water distribution system. The result shows that the proposed approach can be a good performance evaluation method by simply measuring pressures for the PRVs.
        4,500원