Some distributions have been used for diagnosing the lead time demand distribution in inventory system. In this paper, we describe the negative binomial distribution as a suitable demand distribution for a specific retail inventory management application. We here assume that customer order sizes are described by the Poisson distribution with the random parameter following a gamma distribution. This implies in turn that the negative binomial distribution is obtained by mixing the mean of the Poisson distribution with a gamma distribution. The purpose of this paper is to give an interpretation of the negative binomial demand process by considering the sources of variability in the unknown Poisson parameter. Such variability comes from the unknown demand rate and the unknown lead time interval.

Abstract
 1. 서론
 2. 포아송 우도함수
 3. 고정된 조달기간 동안의 포아송 수요발생
 4. 조달기간 동안 상수의 수요발생율을 가지는 포아송 수요발생
 5. 결 론
 참 고 문 헌

• 김우현(한양대학교 산업공학과)
• 안선응(한양대학교 정보경영공학과)