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        검색결과 7

        1.
        2021.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Aluminum nitride having a dense hexagonal structure is used as a high-temperature material because of its excellent heat resistance and high mechanical strength; its excellent piezoelectric properties are also attracting attention. The structure and residual stress of AlN thin films formed on glass substrate using TFT sputtering system are examined by XRD. The deposition conditions are nitrogen gas pressures of 1 × 102, 6 × 103, and 3 × 103, substrate temperature of 523 K, and sputtering time of 120 min. The structure of the AlN thin film is columnar, having a c-axis, i.e., a <00·1> orientation, which is the normal direction of the glass substrate. An X-ray stress measurement method for crystalline thin films with orientation properties such as columnar structure is proposed and applied to the residual stress measurement of AlN thin films with orientation <00·1>. Strength of diffraction lines other than 00·2 diffraction is very weak. As a result of stress measurement using AlN powder sample as a comparative standard sample, tensile residual stress is obtained when the nitrogen gas pressure is low, but the gas pressure increases as the residual stress is shifts toward compression. At low gas pressure, the unit cell expands due to the incorporation of excess nitrogen atoms.
        4,000원
        2.
        2021.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        To improve the shortcomings and expand the advantages of the single-roll melt drag method, which is a type of continuous strip casting method, the melt drag method with a molding belt is applied to AZ31 magnesium alloy. By attaching the forming belt to the melt drag method, the cooling condition of the thin plate is improved, making it possible to manufacture thin plates even at high roll speed of 100 m/min or more. In addition, it is very effective for continuous production of thin plates to suppress oxidation of the molten metal on the roll contact surface by selecting the protective gas. As a result of investigating the relationship between the contact time between the molten metal and the roll and the thickness of the sheet, it is possible to estimate the thickness of the sheet from the experimental conditions. The relationship between the thin plate thickness and the grain size is one in which the thinner the thin plate is, the faster the cooling rate of the thin plate is, resulting in finer grain size. The contact state between the molten metal and the roll greatly affects the grain size, and the minimum average grain size is 72 μm. The thin plate produced using this experimental equipment can be rolled, and the rolled sample has no large cracks. The tensile test results show a tensile strength of 303 MPa.
        4,000원
        3.
        2021.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        An investigation is performed to clarify the manufacturing conditions of pure magnesium and AZ31 magnesium alloy thin plate using the melt drag method. By the melt drag method, suitable for magnesium molten metal, pure magnesium can be produced as a continuous thin plate with a thickness of 1.4 mm to 2.4 mm in the range of 5 m/min to 20 m/min of roll speed, and the width of the thin plate to the nozzle outlet width. AZ31 magnesium alloy is able to produce a continuous sheet of thickness in the range of 5 m/min to 30 m/min in roll circumferential speed, with a thickness of 0.6 mm to 1.6 mm and a width of the sheet matching the nozzle outlet width. In the magnesium melt drag method, the faster the circumferential speed of the roll, the shorter the contact time between the molten metal and the roll, and it is found that the thickness of the produced thin plate becomes thinner. The effect of the circumferential roll speed on the thickness of the thin plate is evident in the low roll circumferential region, where the circumferential speed is 30 m/min or less. The AZ31 thin plate manufactured by the melt drag method has a finer grain size as the thickness of the thin plate decreases, but it is currently judged that this is not the effect of cooling by the roll.
        4,000원
        4.
        2017.10 구독 인증기관·개인회원 무료
        나무주사제의 약제처리 오류(중복처리 또는 천공 후 약제 미처리)로 인한 방제예산의 낭비를 방지하고, 나무주사1회 처리로 소나무재선충과 매개충인 솔수염하늘소를 동시에 방제할 수 있는 ‘시인성 (視認性) 나무주사제(Acetamiprid+Emamectin benzoate SL)’의 실용성을 검증하였다. 시인성 확보를 위해 발색보조제를 첨가한 나무주사제는약제 처리 후 약 1개월간 약제처리 여부를 확인할 수 있는 시인성을 확보하였으며, 소나무 수체 내 약제의 전달력및 잔류성은 기존 제품(발색보조제무첨가) 대비 비등 이상이었다. 특히 2월~5월 사이에는 나무주사 시기에 관계없이솔수염하늘소에 대한 약효가 우화종료시기인 7월말까지 지속되므로 나무주사 1회 처리로 소나무재선충과 솔수염하늘소를 동시에 방제 가능하여, 솔수염하늘소 성충우화기에 수관처리하는 살충제를 대체할 수 있을 것으로 판단된다.
        5.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The e-CALLISTO is a network of CALLISTO (Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories) spectrometers which detect solar radio bursts 24 hours a day in frequency range 45-870 MHz. The number of channels per spectrum is 200 and the time resolution of whole spectrum is 0.25 second. The Korean e-CALLISTO station was developed by Korea Astronomy and Space Science Institute (KASI) collaborating with Swiss Federal Institute of Technology Zurich (ETH Zurich) since 2007. In this paper, we report replacement of the tracking mount and development of the control program using Visual C++/MFC. The program can make the tracking mount track the Sun and schedule CALLISTO to start and to finish its observation automatically using the Solar Position Algorithm (SPA). Daily tracking errors (RMSE) are 0.0028 degree in azimuthal axis and 0.0019 degree in elevational axis between 2014 January and 2015 July. We expect that the program can save time and labor to make the observations of solar activity for space weather monitoring, and improve CALLISTO data quality due to the stable and precise tracking methods.
        4,000원
        6.
        2010.05 구독 인증기관·개인회원 무료
        천안시 입장면에 위치한 두 곳의 포도원에서 꽃매미의 산란위치에 따른 난괴수를 조사하였다. 또한 합판과 부직포, 인삼용 차광천을 이용하여 인위적인 산란장소를 제공하여 경사유무, 차광 정도, 표면 특성에 따른 산란 정도를 조사하였다. 포도원 내부보다는 외곽에(F=1860.97, p<.0001), 수직보다는 경사진 곳에(F=1941.73, p<.0001), 포도나무보다는 시멘트 지주에(F=905.71, p<.0001), 노출된 곳보다는 식물체에 가려진 곳에(F=4785.73, p<.0001) 더 많이 산란을 하는 것으로 나타났다. 포도원 외곽에 위치하고 경사져 있으며 식물체로 가려진 시멘트 지주에서 평균 51.1개의 난괴가 발견되었으며, 수직이지만 식물체로 가려진 시멘트 지주에서도 평균 23.5개의 난괴가 발견되었다. 인위적인 산란장소를 제공한 실험에서도 차광정도(F=6.76, p=0.0026), 표면특성(F=66.76, p<.0001), 경사유무(F=7.98, p=0.0069)에 따라 산란된 난괴수에 유의한 차이가 존재하여 포도원에서의 결과와 동일하였으며 차광정도와 표면특성(F=4.45, p=0.0169) 그리고 표면특성과 경사유무(F=4.90, p=0.03160) 사이에는 유의한 상호작용이 존재하였다.