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        검색결과 252

        121.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In general, a valve body of the automatic transmission(AT) is controlled by the clutch, the brake and lubricating oil flow in a hydraulic system and lubricant flow for each valve can be adjusted independently. To increase the lifetime of AT, the lubrication flow rate in a valve body for a 6 speed AT based parallel hybrid electric vehicle must be provided with proper oil distribution and control. In this study, we carried out several experiments without the inner parts of AT and with a AT assembly. The variation of the flow rate on oil temperature and pressure between an oil supply port and the outlets of the lubrication port was evaluated and analyzed. In the case of AT without the inner parts, it was evident that as the oil required for an operation of the clutch and brake was discharged from the outlet port, the flow rate from each lubrication port is decreased. However, the flow rate of the AT assembly was slightly increased. In addition, the lubrication flow rate was increased with increasing the oil temperature, and also it was reduced with increasing the oil pressure. Details of the resulting data are discussed.
        4,000원
        122.
        2011.05 구독 인증기관·개인회원 무료
        The sweetpotato whitefly, Bemisia tabaci, acts as a vector of more than 100 plant viruses. B. tabaci is known to harbor a primary endosymbiont (Portiera) and 6 secondary endosymbionts (Arsenophonus, Cardinium, Fritschea, Hamiltonella, Rickettsia and Wolbachia). These endosymbionts play important roles in the acquisition and transmission of plant viruses. Using PCR analysis, we identified endosymbiotic bacteria in various B. tabaci populations collected from different places of Korea. Distribution of endosymbionts was different according to the biotype of B. tabaci. Subsequently, their relative densities of endosymbionts were compared between TYLCV-viruliferous and non-viruliferous populations of the Q biotype using quantitative realtime PCR. We found that the densities of Portiera, Cardinium and Hamiltonella are higher in viruliferous than non-viruliferous whiteflies. Our results suggest the role of endosymbiont for the TYLCV transmission of whiteflies.
        123.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Since there had been the first human outbreak of novel influenza A/H1N1 in Mexico, it has become pandemic throughout the world. In the Republic of Korea, the first human case was on May, 2009 and National Veterinary Research and Quarantine Service (NVRQS) has started monitoring novel influenza A/H1N1 on domestic swine farms. The first positive case was detected on 14, Dec, 2009 and until now, we have had total 17 positive cases. From the first case, we did epidemiological investigation on introduction and transmission of virus to pigs. We have concluded that virus had been introduced from humans to pigs, possibly from October to November, 2009 in our country. There were direct and indirect factors including the vehicles transporting veterinary medicine, feed, etc. related to transmission of virus from farm to farm. However, breeding pigs seem to be extrinsic to transmitting factors. Upon the epidemiological investigation, the off-limits of visitors to farms and the disinfection is thought to be critical for blocking the introduction and transmission of novel influenza A/H1N1. In addition, collecting and analyzing the genetic informations of influenza virus is important for predicting and handling the new pandemic influenza in the future.
        4,000원
        124.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper describes an investigation of an outbreak of foot-and-mouth disease (FMD) in Republic of Korea in January 2010. In this paper, we investigated introduction to the index farm from overseas countries, transmission from index farm to other outbreak farms. The introduction factors were divided direct, indirect factors or airborne spread factor. Based on the epidemiological data, clinical information and other data, in these introduction factors, it was likely that outbreak of FMD in index farm was due to international goods or employees from overseas countries (including China). There were other suggested causes in index farm. But it was less likely that outbreak of FMD in index farm have occurred by other causes. The transmission factors from index farm to other farms were also divided direct, indirect factors or airborne spread factor. In these transmission factors it was possible to make assumptions from index farm to other outbreak farms that the FMD virus was transmitted through animal treatment, persons concerned and persons (who were) attended farmers’ assembly.
        4,000원
        125.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        World Widely, a lot of gearboxes are being developed for the increase of fuel efficiency. Among them, CVT has an infinite gear and shifts gear at the best situation which makes it have no impact by changing speed and reduce the expense of fuel. We designed and manufactured 2ranked gearbox for V-belt similar to CVT. We studied an energy generated when it is functioning and had an experiment of forwarding power of it. These studies are planned to find out its functions and the efficiency of forwarding power of it.
        4,000원
        126.
        2010.05 구독 인증기관 무료, 개인회원 유료
        네트워크 기술과 하드웨어의 발전으로 인해 영상 서비스 분야에서 많은 응용 서비스 기술이 등장하고 있다. 이 중에서도 IPTV는 대용량 멀티미디어 스트리밍 기술이 적용되면서 그 수요가 기하급수적으로 증가하고 있다. 만족할만한 IPTV 서비스를 제공해 주기 위해서는 안정적인 전송자원을 확보하는 것이 필수적이다. 본 논문에서는 IPTV 서비스를 위한 전송자원 확보를 위해 기존의 AVB기술을 기반으로 하여 만족할만한 전송서비스 품질(QoS)를 보장하는 방법을 제안한다. 단일 시간동기화와 균형적인 평균 전달 지연 시간을 고려한 시간동기화 기술을 적용하여 IPTV 서비스의 전송 품질을 보장하고자 한다.
        5,100원
        127.
        2010.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 우리나라의 대표적 수입 곡물인 콩의 주요 교역국들의 생산, 소비, 무역 및 재고 동향과 각 국의 생산변동에 따른 조정유형 분석을 수행한 후, 이를 바탕으로 각국의 국제시장 전이효과를 계측하였다. 분석결과 최근 콩의 국제시장 전이효과가 주요 생산국인 브라질, 파라과이, 캐나다 등을 중심으로 증대되고 있으며, 대부분의 국가가 재고보다는 소비와 무역을 통해 생산변동을 조절하고 있는 것으로 나타나 국제 콩 시장의 불안정성 증가가 예상된다. 따라서 대규모 콩 수입국인 우리나라는 일정량의 국내생산기반 유지, 적절 한 재고정책의 활용, 선물시장의 활용, 수입선 다변화 등과 같은 해외조달능력의 향상을 통한 안정적인 국내 콩 수급 방안 마련이 시급한 것으로 나타났다.
        4,300원
        128.
        2009.12 구독 인증기관 무료, 개인회원 유료
        Medial vestibular nucleus (MVN) neurons are involved in the reflex control of the head and eyes, and in the recovery of vestibular function after the formation of peripheral vestibular lesions. In our present study, whole cell patch clamp recordings were carried out on MVN neurons in brainstem slices from neonatal rats to investigate the actions of a group I metabotropic glutamate receptor (mGluR) agonist upon synaptic transmission and ionic currents. Application of the mGluR I agonist (S)-3,5- dihydroxyphenylglycine (DHPG) increased the frequency of miniature inhibitory postsynaptic currents (mIPSCs) but had no effect upon amplitude distributions. To then identify which of mGluR subtypes is responsible for the actions of DHPG in the MVN, we employed two novel subtype selective antagonists. (S)-(+)--amino-a-methylbenzeneacetic acid (LY367385) is a potent competitive antagonist that is selective for mGluR1, whereas 2-methyl-6-(phenylethynyl)-pyridine (MPEP) is a potent noncompetitive antagonist of mGluR5. Both LY367385 and MPEP antagonized the DHPG-induced increase of mIPSCs, with the former being more potent. DHPG was also found to induce an inward current, which can be enhanced under depolarized conditions. This DHPG-induced current was reduced by both LY367385 and MPEP. The DHPG-induced inward current was also suppressed by the PLC blocker U-73122, the IP₃ receptor antagonist 2-APB, and following the depletion of the intracellular Cα2+ pool by thapsigargin. These data suggest that the DHPG-induced inward current may be mainly regulated by the intracellular Cα2+ store via the PLC-IP3 pathway. In conclusion, mGluR I, via pre- and postsynaptic actions, may modulate the excitability of the MVN neurons.
        4,000원
        130.
        2009.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Automobiles with a combustion engine use a transmission for increasing drive force, reverse-move and maintaining non-load condition in general. In the Electric automobile system, output-axial can be operated just by controlling the motor manipulated with power. It also does not need reverse-gear by rotating the motor in the opposite direction. Designed to assemble two different types of planetary gear ratio and to be input torque of input-axial in sun gear and divide ring gear Ⅰ, Ⅱ and then after one of ring gear is fixed, in accordance with the planetary gear velocity ratio, the first gear has 0.136 decreased speed and second gear has 0.240 decreased speed, separately. While the planetary gear type transmission showed over the 92% of efficiency in the all of velocity range. The transmission proposed in this study can be expected to apply to the electric vehicle or others.
        4,000원
        131.
        2009.06 구독 인증기관 무료, 개인회원 유료
        Perception of sweet compounds is important for animals to detect external carbohydrate source of calories and plays a crucial role in feeding behavior of animals. Recent progress in molecular genetic studies provides evidence for a candidate receptor (heterodimers with taste receptor type 1 member 2 and 3: T1R2/T1R3), and major downstream transduction molecules required for sweet taste signaling. Several studies demonstrated that the sweet taste signal can be modulated by a satiety hormone, leptin, through its receptors expressed in a subset of sweet-sensitive taste cells. Increase of internal energy storage in the adipose tissue leads to increase in the plasma leptin level which can reduce activities of sweet-sensitive cells. In human, thus, diurnal variation of plasma leptin level parallels variation of taste recognition thresholds for sweet compounds. This leptin modulation of sweet taste sensitivity may influence individuals' preference, ingestive behavior, and absorption of nutrients, thereby plays important roles in regulation of energy homeostasis.
        3,000원
        132.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this thesis, we explain developing processes of the power transmission system for lift truck. Conventional power transmission system had some problems such as spatial constraints or low speed and high torque problem. Because conventional power transmis
        4,000원
        133.
        2008.12 KCI 등재 구독 인증기관·개인회원 무료
        Purpose : To evaluate visual acuity(V A) according to Jight transmissi on of tinted Jenses. Methods : 37 college students in Daegu and Kyungbuk province(24 males, 13 females, a mean age of 22.8±2.0 yrs.) were seJected. AJJ of them had corrected visuaJ acuity of 0.8 or better, no anisometropia of 2.000 or more, no ocuJar and systemic diseases. Gray, brown, red, green, yellow, bJue, pink lenses are tinted in accordance with BS EN 1836(1997) so that Juminous transmittance of the lenses classified 80-90%(0 category), 60-80%(1-1 category), 43-60(1-2 category), 30- 43%(2-1 category), 18-30%(2-2 category). VA was measured with Han's visual acuity churt. Results : ln wearing tinted lens, the VA decreased. the photopic condition at distance, VA with all the tinted Jens decreased except 0 category Jenses of brown, yellow, blue tint and 1-2 category Jens of yellow tint. ln mesopic condition at distance, V A with all tinted Jenses decreased except 0 category Jens of gray tint. ln the photopic condition at near. V A with alJ tinted Jens decreased. In mesopic condition at near distance, VA with alJ tinted Jenses decreased except 0 category Jenses of green and pink tint. ln the photopic condition at distance. the measured corrected VA with all tinted Jenses excepts 2-2 category of gray tinted Jens was 0.8 or better. ln the mesopic condition at distance. the measured corrected VA with all tinted Jenses was Jess than 0.8. ln the photopic condition at near. the measured corrected VA with 2-2 category Jens of gray tint was 0.8 or better. ln the mesopic condition at near, 1-1 category Jens of bJue tint were measured corrected visual acuity Jess than 0.8. 1-2 category of alJ tinted lenses were measured con·ected visual acuity Jess than 0.8. Conclusions : VisuaJ acuity according to color and light transmittance of tinted lenses was different. When choosing tinted lenses, the decreased leveJ of visuaJ acuity needs to be considered.
        134.
        2008.10 구독 인증기관·개인회원 무료
        The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is one of the most important agricultural pests in Japan, that causes retard of plant growth and sooty moulds through excreted honeydew by direct sucking of pholoem sap, and additionally transmits several kinds of plant virus. B. tabaci consists of more than 20 biotypes which possess different ecological or physiological characters but cannot be distinguished from others morphologically. In Japan, exotic B and Q biotypes are the common pests of vegetables, flowers and ornamental plants. B biotype, the silver-leaf whitefly, was first recorded in Aichi Prefecture, Tokai region, in 1989 and expanded its distribution to almost all part of Japan, except for the northern area, within several years. Q biotype was recently found in Hiroshima Prefecture, Chugoku region, in 2004 and is still expanding the distribution in our country. Indigenous B. tabaci biotypes also exist in the southwestern part of Japan: JpL biotype was recorded in Honshu, Shikoku, Kyushu Islands and Nauru biotype was found in Amami and Ryukyu Islands. Although the host plants of these indigenous biotypes include some agricultural crops, these insects are not important as agricultural pests. The most serious problem in vegetable cultivation caused by B. tabaci is an intensive epidemic of the tomato yellow leaf curl disease (TYLCD) which leads to a large yield loss of tomato production in green houses. TYLCD distributes worldwide and it was found in Aich and Sizuoka Prefectures, Tokai region, and Nagasaki Prefecture, Kyushu region, simultaneously in 1996. The distribution of TYLCD expanded mainly in the western part of Japan for several years after its first finding, but recently TYLCD started to occur also in the eastern part of Japan, Kanto and Tohoku regions. Tomato yellow leaf curl virus (TYLCV), a pathogen of TYLCD, is transmitted by B or Q biotype of B. tabaci in a persistent manner. Although an effective control of B. tabaci is essential for decreasing of TYLCD outbreaks in tomato green houses, it is quite difficult to control these whiteflies only by the spraying of chemically synthesized insecticides due to their insecticide resistance. Especially, Q biotype shows a high level of resistance to pyriproxyfen and neonicotinoid insecticides. To avoid the development of insecticide resistance in B. tabaci, we are trying to combine some different control methods, for example, use of a fine mesh screen to prevent the invasion of vector insects, use of the physical-coating or microbial insecticides with the chemically synthesized insecticides to prevent the reproduction of vector insects, closing and steaming of a green house at the end of tomato cultivation to kill vector insects and prevent their escape from there, as an integrated pest management (IPM) system for B. tabaci and TYLCD control. We are also breeding TYLCV resistant varieties of tomato and considering how to use these varieties effectively.
        135.
        2008.05 구독 인증기관·개인회원 무료
        Tsutsugamushi disease, caused by a rickettsial bacteria known as Oriental tsutsugamushi, is one of the most febrile illnesses occurring throughout Korea during fall. O.tsutsugamushi is transmitted by the bite of infected, immature mites of the genus Leptotrombidium. The mites have four-stage life cycles : egg, larva, nymph, and adult. The larva is the only stage that can transmit the disease to humans and other vertebrates, since the other life stages do not feed on the host. During the process of obtaining a blood meal, they may either acquire the infection from the host or transmit the rickettiae to the other rodents or humans. The model can be divided the life cycle of mite into 2 stages : Larva and Adult. And the larva stage can be subdivided according to the phase of activity : questing and feeding. Mites enter either the susceptible questing larvae or infectious questing larvae through birth. When the larva bites an infectious hosts, then the larva moves from the susceptible questing to the infectious feeding class with some probability. On the other hand, hosts also enter the susceptible class through birth. And when an infectious larva bites a susceptible host, then the host enters the infectious class with some probability. In this talk, we introduce our mathematical model for the tsutsugamushi disease, and show the existence and stability condition of the disease-free equilibrium, which is a kind of threshold for the tsutsugamushi disease transmission, and also define the basic reproduction ratio R0. And we discuss about R0 related to all parameters.
        136.
        2008.05 구독 인증기관·개인회원 무료
        The paternal sex ratio (PSR) chromosome is considered as an extremely selfish genetic element. It has only been found in the two hymenopteran insects- Nasonia and Trichogramma- with haplodiploid sex determination. When an egg is fertilized by sperm bearing PSR, the paternal genome is destroyed by PSR soon after fertilization resulting in haploid restoration and the egg develops into a male with only the maternal genome and PSR itself. Recently PSR is paid much attention, since it may be used for controlling haplodiploid pests. PSR can be successfully transferred from its natural host, T. kaykai to the novel host, T. deion. In the two hosts another sex ratio distorter, Wolbachia, is found. Wolbachia is a cytoplasmically inherited bacterium that induces parthenogenesis in this genus resulting in female offspring production without fertilization. The transmission efficiency of PSR in T. deion is lower than that in T. kaykai and is negatively influenced by the Wolbachia infection. The results show that 1) there is a negative host genetic background effect on the transmission of PSR in the novel host, 2) the transmission efficiency becomes even lower, when PSR males are infected with Wolbachia. The results imply that complex interactions among the bacterium, PSR and the species specific genetic background.
        137.
        2008.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The underwater sound transmission system(USTS) was experimentally made to monitor the cetacean's appearance by telemetry, and then its system was tested to evaluate its performance from July to October, 2007 at the Kimnyeong berth and the dolphin's breeding ground of Pacific Land in Jeju island, respectively. The results showed that the sweep sound in the trial experiment and the whistle sound of bottlenose dolphin(Tursiops truncatus) were favorably received by telemetry. Therefore, we could confirm the USTS is able to monitor the cetacean's appearance in real time without direct observation at sea within effective range of code division multiple access(CDMA) communication method.
        4,000원
        138.
        2007.12 구독 인증기관 무료, 개인회원 유료
        The superficial dorsal horn, particularly substantia gelatinosa (SG) in the spinal cord, receives inputs from small-diameter primary afferents that predominantly convey noxious sensation. Reactive oxygen species (ROS) are toxic agents that may be involved in various neurodegenerative diseases. Recent studies indicate that ROS are also involved in persistent pain through a spinal mechanism. In the present study, whole cell patch clamp recordings were carried out on SG neurons in spinal cord slice of young rats to investigate the effects of hydrogen peroxide on neuronal excitability and excitatory synaptic transmission. In current clamp condition, tert-buthyl hydroperoxide (t-BuOOH), an ROS donor, depolarized membrane potential of SG neurons and increased the neuronal firing frequencies evoked by depolarizing current pulses. When slices were pretreated with phenyl-N-tert-buthylnitrone (PBN) or ascorbate, ROS scavengers, t-BuOOH did not induce hyperexcitability. In voltage clamp condition, t-BuOOH increased the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs), and monosynaptically evoked excitatory postsynaptic currents (eEPSCs) by electrical stimulation of the ipsilateral dorsal root. These data suggest that ROS generated by peripheral nerve injury can modulate the excitability of the SG neurons via pre- and postsynaptic actions.
        4,000원
        139.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        There are many types of reduction drives for industrial uses. However, it is essential to use precision reduction drives for accuracy of position controls on robot systems. Among the precision reduction drives, the cycloid reduction drive is well known for its high performances and widely used in precision industrial field. Cycloid reduction drives are mainly used in manipulators in robot system requiring a characteristic of a high precision control. When we design this cycloid reduction drive, there are many factors that must be considered. First, a geometrical analysis of a tooth shape must be drawn from the basic concept. Secondly, load distribution, stress distribution and sliding velocity on a tooth should be calculated exactly. Finally, a computer software to optimize the design of a cycloid tooth needs developing. In this study, many different kinds of factors concerning the characteristic of a cycloid tooth were researched on the basis of the analysis of load, stress and sliding velocity on a tooth. The computer expert system to design the cycloid reduction drive was developed using a Visual C++ compiler. In conclusion, the most important factors can be obtained easily as the user put the simple input data.
        4,000원
        140.
        2007.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 풍하중에 대한 기존 송전철탑의 좌굴 및 구조적 안전성을 평가하기 위해서 축소부분구조 실험을 수행하였다. 원 송전철탑에 작용하는 중력 및 풍하중을 재현하기 위해서 1/2크기의 상사법칙을 적용한 축소모델의 상부에 설치된 삼각형태의 지그를 이용하여 가력하는 방법을 고안하였다. 설계하중에 대한 실험체의 안정성을 평가하기 위해서 예비수치 해석을 수행한 결과, 계산된 주주재의 축력은 허용좌굴하중의 사이에 분포하고 있음을 확인하였다. 최대허용좌굴 하중의 270%까지 가력한 결과, 주주재의 면외거동을 구속하는데 취약한 절점에서 발생한 국부좌굴로 인하여 송전철탑이 파괴되었다. 하중-변위 곡선, 변위, 부재별 변형률을 검토한 결과, 이러한 국부좌굴의 발생은 동일한 단면내에서도 휨모멘트로 인해 항복응력에 도달하는 시간이 위치별로 다르기 때문에 변형의 불균형에 의해서 발생한 부가적인 편심에 기인한 것으로 판단된다.
        4,300원