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        검색결과 507

        361.
        1997.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We carried out high-resolution(FWHM=3' .3) HI 21 cm observations of the supernova remnant(SNR) PKS0607+17 and HII region S261 using Arecibo 305-m telescope. The observation was to investigate whether the high-velocity(HV) gas detected in the southern area of PKS0607+17 by Koo & Heiles(1991) is physically associated with the SNR or not. The velocity of the HV gas ranges from +64 km/s to +87 km/s, which is difficult to result from the Galactic rotation. The HV gas could be the gas accelerated by supernova blast wave. However, because the observation of Koo and Heiles(1991) was carried out using Hat Creek radio telescope(FWHM ≃ ≃ 36'), the association of the HV gas with the SNR could not be investigated. Using the Arecibo HI 21cm data, we have found that the HV gas appears m the southern part of the SNR and its velocity ranges from +61 km/s to +77 km/s. But the HV gas is scattered m the whole field, not only toward PKS0607+17 but also outside the SNR Accordingly the HV gas is probably not associated with the SNR, but is accidentally aligned along the same line of sight toward the SNR. Instead we have found that HI clouds at low velocities could be possibly associated with the SNR. In Arecibo HI 21cm channel maps the HI gas seems to surround the southern boundary of the SNR at VLSR VLSR = +19.6 ~ +40.2 km/s. But because the region of the Arecibo HI 21cm observation is not wide enough to examine the HI gas distribution, we investigated this area using the Berkely low-latitude HI survey data(Weaver & Williams 1974) too. There we found HI gas surrounding the radio continuum boundary of PKS0607+17 at VLSR VLSR = +21.6 ~ +258 km/s. It is possible that this HI gas is associated with the SNR, in which case, the velocity of the SNR Vo Vo ≃ ≃ +26 km/s, its distance d ≃ ≃ 12.5 kpc and its radius R ≃ ≃ 145 pc. If we assume that the expansion velocity is ~10 km/s, then the age of the SNR is ∼4.4×106 ∼4.4×106 years. PKS0607+17 could be one of the oldest SNRs in the Galaxy. We also studied HI propertities of the HII region S261, which is ∼1∘ ∼1∘ away from PKS0607+17. There has been no high-resolution m 21 cm observational study on S261. We discovered HI cloud located at the north-eastern part of S261 at VLSR VLSR = +5 km/s ~ +10 km/s, which is possibly associated with the HII region. The central velocity of the HI cloud VLSR VLSR = +7.2 km/s and the corresponding distance d = 1.5 kpc. This velocity is comparable to the radio recombination line velocities.
        5,800원
        364.
        1996.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have developed a 5GHz continuum receiver system. The receiver is a direct type receiver. In order to reduce the noise due to the fluctuation of the gain in the amplifiers, the system employs the Dicke switching method. We made the 5GHz low-noise amplifier and the bandpass filter. The low-noise amplifier gives ∼35dB ∼35dB gain and has ∼210K ∼210K noise temperature. The bandpass filter has a passband between 4.3 and 5.4GHz. We also made switch driver, video amplifiers, phase detector, and integrator. Using a 1.8 meter offset parabolic antenna, we measured the efficiency of the system. Since the antenna does not have a driver to track objects, observations were performed with the antenna fixed. The measured noise temperature of the system is ∼650K ∼650K . From the observation of the blank sky, noise level was measured. It was found that the systematic noise(∼0.5K ∼0.5K : peak to peak value) is much larger than the thermal noise. The systematic noise is possibly related to the stability of the DC power supplied to the receiver system. Besides the noise of the system, it was found that the airplanes are the very serious noise sources. We measured the radio flux of the Sun using the developed system. The observed radio flux of the Sun is ∼106Jy ∼106Jy , which is close to the known value of the quiet Sun. The test observation of the Sun shows that the angular beam size of the antenna is ∼2.2∘ ∼2.2∘ .
        4,800원
        365.
        1996.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have performed the high resolution computer simulation with 1D spherical hydrodynamic code in order to study the dynamical evolution of supernova ejecta interacting with a pre-existing fast wind structure. The fast wind structure has been calculated with Min=3×10−6M⊙yr−1 Min=3×10−6M⊙yr−1 and υin=1000km/sec υin=1000km/sec , which velocity is higher than the critical velocity relating to the initial radiative cooling. The fast wind becomes initially adiabatic. After a shell formation time of ∼4000yrs ∼4000yrs , the wind becomes radiative cooling at the shell zone, forming a thin dense radiative shell and an adiabatic wind bubble afterward. When supernova explodes in the wind center at 20,000yrs after the wind evolves, the supernova ejecta, which has a dense distribution of ρ∝r−n ρ∝r−n (here we have n = 9), interacts initially with, the understood wind zone, producing forward and reverse shocks. The reverse shock heats the supernova ejecta and its temperature increases. In this study, as the mass of the supernova ejecta is larger than that of the wind shell (Mej=5M⊙ Mej=5M⊙ , Msw=2M⊙ Msw=2M⊙ ), we can conform two shell structures: an outer shell by the supernova ejecta and a secondarily shocked wind shell by it. The secondarily shocked wind shell should accelerates in this case to be R-T unstable, consequently producing the knots
        5,700원
        368.
        1996.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have built a near-infrared imaging camera with a PtSi array detector manufactured by the Mitsubishi Company. The PtSi detector is sensitive in the wavelength range 1 to 5μm 5μm . Quantum efficiency of PtSi is much lower than that of InSb and HgCdTe types. However, the PtSi array has advantages over the latter ones: (i)The read-out noise is very low; (ii)the characteristics of the array elements arc uniform and stable; (iii)it is not difficult to make a large PtSi array; and (iv) consequently the price is affordably low. The array used consists of 512×512 512×512 pixels and its size is 10.2mm×13.3mm 10.2mm×13.3mm . The filter wheel of the camera is equipped with J, H, K filters, and an aluminum plate for measuring the dark noise. The dewar is cooled with liquid nitrogen. We have adopted a method of installing the clock pattern and the observing softwares in the RAM, which Gill he easily used for other systems. We have developed a software with a pull-down menu for operating the camera and data acquisition. The camera has been tested by observing δ δ Orionis.
        6,400원
        369.
        1996.12 구독 인증기관 무료, 개인회원 유료
        8,700원
        370.
        1995.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hydranautic사의 셀룰로오즈 아세테이트 재질로 된 RO S/W 4040을 이용하여 2성분계의 붕산수용액 및 붕산수에 함유된 실리카의 3성분계 수용액에 대하여 조업온도, 운전압력 및 공급유량 변화가 투과량, 붕산회수율, 실리카 배제율에 미치는 영향에 대한 실험을 수행하였다. 붕산수용액의 경우 35℃, 20atm 및 원액의 유속이 2.82l/min에서 붕산회수율 및 투과도는 각각 58.7% 및 2.82l/min, 35℃, 10atm에서는 68.1% 및 1.56l/min이었다. 또한 실리카 및 붕산이 함께 함유된 용액의 경우 35℃, 3.2atm에서 붕산회수율 69.7%, 실리카 배제율 97.5% 및 투과도 0.47l/min의 결과를 보여주었으며, 35℃, 20atm에서 원액의 유속이 2.92l/min의 경우 붕산회수율 56.4%, 실리카 배제율 96.1% 및 투과도 2.72l/min의 결과를 보여 주었다.
        4,000원
        373.
        1995.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        8,900원
        376.
        1994.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 시험의 목적은 온실의 주년계획이용을 위해서 하기주간 냉방의 방법으로 heat pump를 이용한 냉수냉방과세무냉방의 효율성을 검사했고 하기 토마토 배꼽썩음병 발생을 억제하기 위하여 냉방과 함께 과실에 송풍처리와 식물체 전체의 공기유동을 촉진시켜주는 처리를 했다. 시험결과는 다음과 같다. 1) 냉수냉방구간 기온은 13시경 온실내 기온보다 약 10℃이상 낮았고, 세무냉방구간 하부의 기온은 13시경 온실내 기온보다 약 5℃ 낮았다. 2) 과실에 송풍처리는 냉방방법에 상관없이 배꼽썩음병이 방지됐고, 냉수냉방 무송풍구의 배꼽썩음병 발생율은 34.5%, 세무냉방 무송풍구는 54.5%, 세무순환냉방구는 78%였다. 냉방효율면에서는 냉수냉방 방법이 충분히 생육한계온도 이하로 냉각되었고, 배꼽썩음병 발생율에서도 세무냉방보다 낮았다. 세무냉방은 재배구간의 공기를 유동시킴으로서 약 24%증가했다. 그러므로 토마토 배꼽썩음병 발생에 관한 환경요인은 온도보다는 습도가 밀접한 관계가 있는 것으로 생각되어진다.
        4,000원