Used as a mixing distribution for an unknown Poisson parameter, the gamma distribution leads to the negative binomial distribution. The hyperparameters of the gamma distribution have their own meanings according to what the Poisson parameter represents. Different sources in the randomness of the Poisson parameter give different interpretations of the negative binomial distribution.

A proper performance evaluation of ATM (Asynchronous Transfer Mode) multiplexer is essential for stable management of ATM networks. We model the on/off traffics entering to the ATM switch as a Markov renewal process (MRP) and propose a performance evaluation method of ATM multiplexer by modeling the system as a discrete time MR/D/1/B queueing system, whose input process is the superposed MRP and present a performance analysis by finding CLP(Cell Loss Probability).

한국산 알뾰족반날개속에 대한 분류학적 연구를 수행하였다. 조사된 8종에서 한국산 미기록종은 다음 7ㅈㅇ으로 밝혀졌다. Sepedolhilus amurensis Schilke, S. fimvriatus(Sharp), S. marshami(Stephens), S. simulans Nakne and Sawada, S. suvarmatus Naomi and Matuyama, S. tiialis(Sharp), and S. varicornis(Sharp). 한국산 알뾰족반날개속에 대한 검색표를 작성하였고, 종을 기재하였으며, 진단 형질을 조식하였다.

A modification of the sol-gel method to obtain phase pure superconducting oxides is described. The method starts from organic salts of yttrium, barium and copper, such as acetates, and avoids the sudden and uncontrollable decomposition of the organic fraction which occurs if nitrates are used as starting materials. The aqueous solution obtained with citric acid in an alkaline medium is concentrated under vacuum. The solid so prepared is decomposed at about 300℃ thus giving an oxide precursor containing well dispersed yttrium, barium and copper. Pyrolysis at 850 - 920℃ followed by oxygen annealing gives the superconducting orthorhombic 123 phase. The results of TGA/DTA of the precursor, as well as XRD, electrical and magnetic property measurements on the pyrolysis products are presented and discussed.

한국산 가는목도랑반날개 족의 분류학적 연구를 수행하였다. 국내에서 처음으로 보고되는 3종의 [Falagria sulcata (Paykull), Myrmecopora (Lamproxenusa ) rufescens (Sharp), and Myrmecocephalus sapida (Sharp)］검색표와 표본사진을 작성하였다.

Decnusa속 (벌목:고치벌과:장승입고치벌아과)의 2종 Dacnusa(Aphanta) sasakawai Takada와 Dacnusa(Dacnusa) nipponica Takada를 한국미기록종으로 보고한다. 전종은 Liriomyza broniae(Kaltenbach), 오이잎굴파리와 Chromatomyia horticole(Gourea), 완두굴파리에 기생했으며, 후종은 완두굴파리에 기생했다.

Highspeed steels (HSS) with a combination of good wear resistance and toughness are finding new, non-cutting applications such as rolls and rollers. In this paper, the research interests are focused on the microstructural evolution of a SMo-6W series high speed steel during HIPping and the effect of HIPping process parameters on its microstructure and properties. HIPping process variables includes; temperature, pressure and hold time. The microstructures of the HIPped HSS were examined by SEM, OM and X-ray diffraction whereas the properties measured were the relative density, hardness, and bend strength at room temperature. In HIPped materials, MC and M6C were the major carbides formed in a matrix of martensite. The effect of powder size on the microstructure and mechanical properties of HIPped materials was insignificant. However, HIPping temperature and hold time strongly affected the carbide size and distribution. The results show that at proper HIPping temperature and pressure conditions, the final products approach the full density ( > 99% RD). The particle boundaries were completely eliminated without an eminent microstructural coarsening. The bend strength was about 2.3 Gpa, which is superior to cast HSS. At excessive HIPping temperatures, rapid carbide coarsening occurred, thus deteriorating the mechanical properties of the P/M steels.