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프레임 차등 신호 영역에서 변환 부호화 방식의 성능 비교
권상근 金烏工科大學校 1991 論文集 Vol.12 No.-
In the hybrid coding of a simple temporal prediction and transform coding., the DCT is adopted in many existing codecs because of it's good performance. The DCT is superior to other transform in the original domain, but in the FD domain, it may not have as good performance as in the original domain because the statistical properties of the FD are quite different from those of original image. In this paper, the statistical properties of FD are derived. Three transforms-DCT, WHT, HCT are compared in the FD domain by means of measures such as energy compaction ratio and rate-distortion function. As a result of simulation, it was found that in FD domain, the HCT have very similar performance to DCT.
Gamma-ray emission from millisecond pulsars - an Outergap perspective
Kwong Sang Cheng 한국우주과학회 2013 Journal of Astronomy and Space Sciences Vol.30 No.3
In this review paper we explain the following gamma-ray emission features from the millisecond pulsars. (1) Why is the dipolar field of millisecond pulsars so weak but the magnetic pair creation process may still be able to control the size of the outergap? (2) A sub-GeV pulse component could occur in the vicinity of the radio pulse of millisecond pulsars. (3) Orbital modulated gamma-rays should exist in the black widow systems for large viewing angle.
Gamma-ray emission from millisecond pulsars - an Outergap perspective
Cheng, Kwong Sang The Korean Space Science Society 2013 Journal of Astronomy and Space Sciences Vol.30 No.3
In this review paper we explain the following gamma-ray emission features from the millisecond pulsars. (1) Why is the dipolar field of millisecond pulsars so weak but the magnetic pair creation process may still be able to control the size of the outergap? (2) A sub-GeV pulse component could occur in the vicinity of the radio pulse of millisecond pulsars. (3) Orbital modulated gamma-rays should exist in the black widow systems for large viewing angle.
外因性 GH의 投與를 통한 韓牛의 成長 및 乳腺의 發達
최광수,최형송,이성철 우석대학교 자원개발연구소 1996 자원개발연구소논문집 Vol.1 No.-
위인성 성장호르몬(rGH)을 14일 간격으로 두당 250mg씩 한우 암송아지(8-12개월령. 160-240kg)에 대한 투여한 후 내인성 성장호르몬, estrogen IGF-I, 체중, 유두용적의 변화 및 IGFBP_3에 대한 processing enzyme의 활성정도를 파악하고져 28일 간격으로 1994년 12월부터 다음해 2월까지 본 연구를 실시하였다. GH 혈청농도는 처리구가 무처리구에 비해 rGH는 투여후 시간이 경과함에 따라 현저히 증가 하였고(p<.01). estrogen과 IGF-I도 처리 후 8주째(P<.05)에 증가를 보였다. 또한 체중(P<.01)과 유두용적(P<.05)도 투여 8주째에 증가를 보였다. 외인성 성장호르몬(rGH)의 投與前에 processing enzyme의 활성이 낮았으나, 250mg의 rGH 투여 후에는 processing enzyme의 활성이 실험기간 내내 현저히 증가하는 것으로 나타났다. 본 연구결과 외인성 성장호르몬은 한우암송아지의 내인성 호르몬 변화를 통하여 성장 및 유선발육을 증진 시킬수 있다는 것을 제시하여 주었다. This experiment was carried out with 12 Korean native heifers(8-12 mth old : body weight, 160-240kg) raised at a farm of Chang-Soo Livestock Cooperatives to evaluate the effects of rGH(recombinant growth hormone) on serum concentrations of growth hormone, estrogen, and IGF-I. weight gain teat volume gain and processing enzyme activity of IGF-I binding protein Ⅲ at 28 day intervals. Animals used were injected with 250mg rGH at 14 day intervals from December. 1994 to February, 1995. The significant difference was found in the group of treatment on the 4th week in the endogenous GH(p<.01) and 8th week in estrogen and IGF-I(p<.05) after injection of rGH in Korean native heifers. There were significant differences between control and treatment group in weight and teat volume on 8th week after treatment(P<.05). Processing enzyme activity before injection of rGH was low. However heifers injected with 250mg of rGH showed that processing enzyme activity of IGF binding protein was highly increased throughout the experiment. Present results suggest that injection of exogenous rGH to heifers can increase the growth performance and mammary gland development of Korean native heifers by the endogenous hormonal changes.
Theoretical Study of Gamma-ray Pulsars
Yuzhe Song,Kwong Sang Cheng,Jumpei Takata 한국우주과학회 2016 Journal of Astronomy and Space Sciences Vol.33 No.2
We use the non-stationary three dimensional two-layer outer gap model to explain gamma-ray emissions from a pulsar magnetosphere. We found out that for some pulsars like the Geminga pulsar, it was hard to explain emissions above a level of around 1 GeV. We then developed the model into a non-stationary model. In this model we assigned a power-law distribution to one or more of the spectral parameters proposed in the previous model and calculated the weighted phaseaveraged spectrum. Though this model is suitable for some pulsars, it still cannot explain the high energy emission of the Geminga pulsar. An Inverse-Compton Scattering component between the primary particles and the radio photons in the outer magnetosphere was introduced into the model, and this component produced a sufficient number of GeV photons in the spectrum of the Geminga pulsar.
Probing Gamma-ray Emission of Geminga and Vela with Non-stationary Models
Yating Chai,Kwong Sang Cheng,Jumpei Takata 한국우주과학회 2016 Journal of Astronomy and Space Sciences Vol.33 No.2
It is generally believed that the high energy emissions from isolated pulsars are emitted from relativistic electrons/positrons accelerated in outer magnetospheric accelerators (outergaps) via a curvature radiation mechanism, which has a simple exponential cut-off spectrum. However, many gamma-ray pulsars detected by the Fermi LAT (Large Area Telescope) cannot be fitted by simple exponential cut-off spectrum, and instead a sub-exponential is more appropriate. It is proposed that the realistic outergaps are non-stationary, and that the observed spectrum is a superposition of different stationary states that are controlled by the currents injected from the inner and outer boundaries. The Vela and Geminga pulsars have the largest fluxes among all targets observed, which allows us to carry out very detailed phase-resolved spectral analysis. We have divided the Vela and Geminga pulsars into 19 (the off pulse of Vela was not included) and 33 phase bins, respectively. We find that most phase resolved spectra still cannot be fitted by a simple exponential spectrum: in fact, a sub-exponential spectrum is necessary. We conclude that non-stationary states exist even down to the very fine phase bins.
Cho-Wing Ng,Kwong Sang Cheng,Jumpei Takata 한국우주과학회 2016 Journal of Astronomy and Space Sciences Vol.33 No.2
A redback system is a binary system composed of a pulsar and a main sequence star. The inverse Compton (IC) scattering between the stellar soft photons and the relativistic pulsar wind will generate orbital-modulating GeV photons. We look for these IC emissions from redback systems. A multi-wavelength observation of an unassociated gamma-ray source, 3FGL J2039.6-5618, by Salvetti et al. (2015) detected an orbital modulation with a period of 0.2 days in both X-ray and optical cases. They suggested 3FGL J2039.6-5618 to be a new redback candidate. We analyzed the gamma-ray emission of 3FGL J2039.6-5618 using the data from the Fermi large area telescope (Fermi-LAT) and obtained the spectrum in different orbital phases. We propose that the spectrum has orbital dependency and estimate the characteristic energy of the IC emission from the stellar-pulsar wind interaction.