• Journal of Biosystems Engineering
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• 제7권1호
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• pp.33-41
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• 1982

When wet-paddy is threshed by conventional auto-fed thresher, the threshed material under the concave is difficult to separate with pneumatic separation only. The development of thresher with an oscillating sieve in addition to the conventional pneumatic separation has been recommanded to improve the separation of grains from straw and chaff having high moisture content. This study was intended to evaluate the separating performance of an oscillating sieve and to obtain the effective operation conditions of the sieve separation. The sieve with oscillating in an elliptical motion was developed and installed in the experimental unit which can simulate the separating operation of the conventional auto-fed thresher. Results of the study are summarized as follows: 1. The flowing velocity of grains on oscillating sieve was increased as the sieve frequency increased but the feed rate did not significantly affect the flowing velocity of grains on sieve. 2. The effects of sieve frequency and the direction of sieve rotation on the separating performance by oscillating sieve show that increasing the frequency of sieve driving crank above the 460 rpm in the same direction of material flow (con-flow) improved the separating performance. 3. The height of grain guide plate and air velocity through the sieve to optimize the separating performance of oscillating sieve were experimentally determined to give about 10cm above the sieve and 7 m/s, respectively.

• 한국항공운항학회지
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• 제26권2호
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• pp.68-75
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• 2018

A flare from an Air Force fighter was abnormally dispensed during the landing. To determine the cause of the abnormal dispensing, fracture analysis, signal analysis and reproduction experiments based on physics of failures were performed. The primary cause of the failure was analyzed to be due to an intermittent fault of an internal circuit card in the AN/ALE-40 chaff/flare dispenser by a broken lid of a capacitor, and the root cause which had derived the primary cause was considered to be an improper handling during the domestic maintenance which were changed from the overseas maintenance due to the DMSMS problem. Therefore, the overall process of the maintenance capability development system was reviewed and alternative ways that considers maintenance error decision aid(MEDA) for system improvement were suggested to prevent further failures.

• Journal of Biosystems Engineering
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• 제19권1호
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• pp.22-32
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• 1994

The combine harvester is considered as an important but complicated and costly machine. The appropriate size of combine has to be developed to use efficiently in Korea. But the combine is such a complicated machine that a complete design model to develop a new type is impossible without understanding the relationship between each factor. The combine capacity is generally limited by the cleaning shoe performance. So a design model for a cleaning shoe has to be developed first for the complete combine design. The objective of this research was to develop a cleaning model of head-feeding combine to predict grain separation from chaff and broken straw on a sieve. A developed physically based model can explain the situation which can happen during separation process. A test apparatus based on the field going machine was developed. The test materials were paddy rice and barley. The data obtained were analyzed by the hand and the video camera. The developed model was verified as an adequate model through the test with $R^2$ of 0.934 and 0.837. The model can be used to evaluate design and operation alternatives of combine and also applied to the automatic control of separation unit of combine with a loss monitering sensors.

• 한국연초학회지
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• 제19권2호
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• pp.102-106
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• 1997

The inluence of styrofoam-panel thickness of floating frame on the seedling growth of flue-cured tobacco(Nicotiana tabacum L.) in the newly developed direct-seed float system was investigated . Floating frame used instead of styrofoam-tray consisted of styrofoam-panel (106×108cm) for floating, eight holes(1.Sx2S.0 cm) to uniform the water, and nutrition supply far seedling and water and nutrition absorption cloth placed on the styrofoam-panel. Each floating-frame may lay eight plastic-trays on it. Eight grades of styrofoam-panel thickness from 26 mm to 46mm and two kinds of media were used in the greenhouse system. Dry cells were found from the styrofoam-panel thickness of 43mm in carbonized chaff, compost and original soil rate of L3-3(v/v) media, and of 37mm in peat and perlite rate of 8-2(v/v) media. The thinner styrofoam-panel produced more tender and succulent seedling with the more trunk and the less root weight. When considering the appearance of dry cell, seedling growth, producing healthy tobacco seedlings, and utilization of styrofoam-panel for two kinds of medias the ideal styrofoam-panel thickness were suggested to be around 34mm for flue-cured tobacco reeling production in the newly developed direct-seeding float system. Key words : tobacco seedlings, float system, medium, styrofoam pannel, dry cell.

• Journal of Advanced Marine Engineering and Technology
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• 제41권2호
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• pp.171-175
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• 2017

The high-tech large warships are minimal and they are always monitored by opponents, and become primary targets when conflicts occur. The improvement in reducing susceptibility has significant importance because it is difficult for a ship to maintain mission capability and functionality once it is damaged. Ordinary decoys are effective only under the premise that the ship has already been exposed. Traditionally, for naval vessels, techniques related to the radar have been used in military stealth techniques to ensure confidentiality. The corner reflector, on the other hand, can produce rather large radar cross sections. Continued use of deceptive systems such as chaff during operations will help to improve survivability of naval ships. From this viewpoint, corner reflector was considered for making radar countermeasures and deception technology. This paper reviews the current status of corner reflector basis decoys and the technical feasibility of corner reflectors for developing structural decoys.

• 대기
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• 제24권1호
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• pp.77-87
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• 2014

The radar reflectivity is significantly affected by ground clutter, beam blockage, anomalous propagation (AP), birds, insects, chaff, etc. The quality of radar reflectivity is very important in quantitative precipitation estimation. Therefore, Weather Radar Center (WRC) of Korea Meteorological Administration (KMA) employed two quality control algorithms: 1) Open Radar Product Generator (ORPG) and 2) fuzzy quality control algorithm to improve quality of radar reflectivity. In this study, an occurrence of AP echoes and the performance of both quality control algorithms are investigated. Consequently, AP echoes frequently occur during the spring and fall seasons. Moreover, while the ORPG QC algorithm has the merit of removing non-precipitation echoes, such as AP echoes, it also removes weak rain echoes and snow echoes. In contrast, the fuzzy QC algorithm has the advantage of preserving snow echoes and weak rain echoes, but it eliminates the partial area of the contaminated echo, including the AP echoes.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.378-387
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• 2000

A rice mill plant with a capacity of 2.5 ton/hr was constructed with automated facilities at Chonnam National University. A simulation model was developed with SLAM SYSTEM for evaluating and improving the rice mill plant. The developed model was validated in the views of hulling efficiency, milling efficiency, milled rice recovery, other materials produced, and bottlenecks in the processes. The results of hulling efficiency, milling efficiency, milled rice recovery in the simulation were, respectively, 81.1%, 89.5%, and 73.1%, while those of the actual mill plant were 81.5%, 90.2%, and 73.5%. The simulation results including the productivity of other materials(chaff, bran, broken rice, stone, etc) produced in the processes were almost similar with those of the actual process. In the simulation the bottlenecks were found out in the processes of separating brown rice and of sorting colored rice. These phenomenon also appeared in the actual process. It needed to increase the hourly capacity of the brown rice separator and the rice color sorter. As the developed model could well express the automated rice mill plant, it could be used for designing and improving rice mill plants. In addition, an alternative model needed to be developed for the system control more accurately and for increasing the rice quality.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권10호
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• pp.1783-1798
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• 2011

Recently, a cryptographic construct, called fuzzy vault, has been proposed for crypto-biometric systems, and some implementations for fingerprint have been reported to protect the stored fingerprint template by hiding the fingerprint features. In this paper, we implement the fuzzy fingerprint vault, combining fingerprint verification and fuzzy vault scheme to protect fingerprint templates. To implement the fuzzy fingerprint vault as a complete system, we have to consider several practical issues such as automatic fingerprint alignment, verification accuracy, execution time, error correcting code, etc. In addition, to protect the fuzzy fingerprint vault from the correlation attack, we propose an approach to insert chaffs in a structured way such that distinguishing the fingerprint minutiae and the chaff points obtained from two applications is computationally hard. Based on the experimental results, we confirm that the proposed approach provides higher security than inserting chaffs randomly without a significant degradation of the verification accuracy, and our implementation can be used for real applications.

• 한국산학기술학회논문지
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• 제13권5호
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• pp.1983-1989
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• 2012

본 연구에서는 외부 장착물이 존재하는 항공기의 안정성 검증을 위해 진동 및 구조해석을 수행하였다. 외부 장착물이 존재하는 경우, 외부 장착물 자체의 정확성 및 안정성을 위한 요구조건이 주어지며, 이와 동시에 외부 장착물이 항공기에 장착되도록 개조된 항공기 구조물의 안정성 문제가 중요하다. 따라서 본 연구에서는 정적 상태에서의 고유주파수 계산을 통한 공진 여부를 조사하고 발사기를 장착하기 위해 개조된 구조물에 작용하는 진동하중을 구하였다. 또한 로컬 모델링 방법을 이용하여 추가 장착 구조물의 구조적 안정성을 검토하였으며 지상 및 비행시험을 통하여 이를 검증하였다.

• 대한가정학회지
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• 제23권2호
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• pp.21-28
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• 1985

This study is to furnish basic data for making appropriate and comfortable pillow. This research was carried out in reference to 260 males and 339 females whose ages are above 20 in Daegu, from Aug. 1. 1984 to Oct. 15. 1984. RESULTS : 1. In the shape of pillow, the western style is more used than Korean style. 2. The mean size, 50.9$\times$29.1 cm, of pillows is too small for the preceding studies of which, the most comfortable size is 65$\times$45 cm. 3. The mean height, 10.1 cm, of pillows is much higher than the appropriate height, 5.0$\pm$1cm, in the preceding studies. 4. The mean weight, 1587g, of pillows seems to be too heavy. 5. The most used stuffing of pillows is fascicular fibers, the second chaff, the third husks of buckweat, the fourth sponge, and then feather, 6. Considering of pillow-slip material, 68.8% of pillows consist o synthetic fiber.7. The mean compression rate 14.5% is much lower than the comfortable compression rate 40~50 in the preceding studies. 8. Considering the way obtainment, ready-made articles are more used than the domestic-made articles. 9. The same pillows are used throughout for seasons, and that seems not to be appropriate because climate is changeable according to seasons in our country. 10. The sterilization by sunlight is rarely carried out and that is unhygienic because pillows used to absord much of sweat during using time.