온라인 쇼핑몰 택배 서비스 품질 기대치에 대하여 제품 종류가 미치는 영향에 관한 연구

서승범,김승범,이진표 한국SCM학회 2020 한국SCM학회지 Vol.20 No.1

The importance of delivery service has increased as the online shopping gained popularity. As the service located in the last phase of the customer purchase experience in online shopping, delivery service had been verified to affect the customer satisfaction and the performance of the company. Following the framework of SERVQUAL where a service quality is defined as the difference between the customer expectation and experience, more information on customer expectation can enhance more efficient utilization of a limited resource by service-level-differentiation. Our work departs from usual approach where customers themselves are categorized and differentiated and we focus on how product category affects service expectation. The hypothesis that different kinds of products entails different level of service expectation is imposed and tested. Especially, we observed that service expectations on each of SERVQUAL elements are dependent on the product category. The empirical results suggest the need of service-level-differentiation on the product category.

수자원의 합리적 배분 방안 마련 기초연구 : 합리적 물 수급 분석 방안 연구

서승범 한국환경정책평가연구원 2019 한국환경정책평가연구원 기초연구보고서 Vol.2019 No.-

■ 연구의 주요 내용 ○ 국가 수자원계획의 물 수급 전망 현황을 파악하고 미흡한 점과 개선방향을 제시 ○ 국내 수자원계획의 물 수급 전망기법의 현황 분석 ○ 물 수급 전망기법 개선 연구 사례분석 ○ 물 수급 전망기법 개선 방향에 대한 시사점 도출 ■ 정책 제안 ○ 목표 이수안전도 도입을 위한 정책 연구가 필요 ○ 광범위한 물 수급 자료의 DB화 추진 필요 ○ 기후변화에 대응하기 위한 중장기적 수자원계획 수립 필요

Asymptotically Optimal Solution for TSF-Constrained Staffing Problem

서승범 대한경영학회 2019 大韓經營學會誌 Vol.32 No.9

Finding the right balance between the customer service and personnel expenditure has been an important task both in practice and academia and in academia this problem was usually approached using a total cost problem. However, it is difficult to directly apply this formulation in practice and hence recent works in queueing systems have investigated this problem with staffing minimization with constraints on quality-of-service constraints. Our work contributes on this stream of works by studying TSF measure, which shows the percentage of customers who waited beyond the prespecified threshold. TSF measures the proportion of customers whose waiting time exceed a certain threshold. It is one the most prevalent kind of quality of service measure, along with ASA, which measures the average of waiting time. TSF measure is intuitive to understand and hence widely been used but has not received sufficient attention in academia. Part of the reason comes from the unnatural property of TSF measure. Once a customer waits more than the threshold, the incentive to serve that customer starkly diminishes since decreasing the eventual waiting time of him does not enhance the performance of the system. Hence a policy that is far from FIFO turns out to be more efficient. Especially we are interested in context where service level differentiation among various classes of customers. Hence, we work on V-model where multiple classes of customer and homogeneous pool of servers exist. Our task is to come up with the minimum possible number of servers while maintaining TSF measure on the pre-defined level. The decision variables are two-kind: number of servers and prioritization policy. The prioritization policy defines which class of customer to server first when a server becomes available. The nature of TSF measure, which tends to give lower priority to the customers who had already waited beyond the threshold, makes the problem more difficult to solve and hence it was usually treated in literature more added conditions or constraints added. We devise an optimal solution of TSF constrained problem without adding more structures. Since the problem is difficult to solve in exact analysis, we apply the heavy traffic technique to solve the problem. First, we show that our suggested staffing level is the lower bound for all the feasible solutions. Second, it is proved that the proposed prioritization policy combined with our staffing level actually is feasible and hence asymptotically optimal.

이차원 소재 및 응용 소자 기술 동향

서승범,장병철,최성율,Seo, Seung-Beom,Jang, Byeong-Cheol,Choe, Seong-Yul 한국정보디스플레이학회 2016 인포메이션 디스플레이 Vol.17 No.3

Minimization of Concave Holding Costs in Queueing System

서승범 연세대학교 경영연구소 2020 연세경영연구 Vol.57 No.2

Since the advent of basic  rule, minimization of holding costs has been one of the most fundamental problems in queueing theory. The first results on holding cost minimization was under the linear cost assumption and the more general case of convex costs has been solved with help of queueing approximation method named heavy traffic. Even with many sophisticated solutions on general settings, there is scarce literature that goes beyond convex or linear cost structure. Especially, a holding cost minimization problem with concave cost structure has not been discuessed yet. As far as we know, our work is the first to study concave cost structure in queueing theory. We study how the customers from multiple classes should be prioritizized. We figure out that so-called bang-bang policy is always included in the set of optimal prioritization policies when the costs are concave and that all the optimal solutions to strict concave costs are bang-bang. With this property, we construct a simple and general solution for the concoave cost minimization problem. We also provide a condition that produces a solution that assigns the whole workload to a single class.

히어로, 안티히어로, 빌런의 캐릭터 유형에 따른 유제품 유통기한 소비자 평가

서승범,김지호 한국소비자·광고심리학회 2023 한국심리학회지 소비자·광고 Vol.24 No.2

This study attempted to confirm evaluation of consumers according to the character type, And it was verified whether these effects changed according to the sell by date and the involvement. Hero characters can alleviate perceived risk by providing as sense of security and protection, but villain and anti-hero were expected to have different effects. Accordingly, an online survey of 387 people was conducted, and results are as follows. First, consumers perceived the highest level of performance risk in heroes, which showed a significant difference from villain. However, antiheroes showed no difference from both types. Second, the difference in character types for purchase intention was found to be signnificant, and it was high in the order of villain, anti-hero, and hero. Based on this, the sell by date date, involvement, and the effect of the character type of the package were discussed. 본 연구는 캐릭터 유형에 따른 소비자의 평가를 확인하고자 하였다. 그리고 유통기한 잔여일과 소비자의 관여 수준에 따라, 이러한 효과가 달라지는지를 검증하였다. 히어로 캐릭터들은 안정감과 보호감을 제공함에 따라, 지각된 위험을 완화할 수 있지만, 빌런과 불완전한 히어로인 안티히어로 캐릭터들은 서로 다른 효과를 낼 수 있을 것으로 기대되었다. 이에 총 387명을 대상으로 한 온라인 설문조사를 시행하였으며, 조사 결과는 다음과 같다. 먼저, 소비자들은 히어로에서 가장 높은 수준의 수행적 위험을 지각하였으며, 이는 빌런과 유의한 차이를 보였다. 그러나 안티히어로는 두 유형 모두와 차이를 보이지 않았다. 둘째, 구매 의도에 대한 캐릭터 유형의 차이가 유의한 것으로 나타났으며, 빌런, 안티히어로, 히어로 순으로 높은 구매의도를 보였다. 이를 바탕으로 유통기한 잔여일, 관여 수준, 패키지의 캐릭터 유형이 가지는 효과에 대해 논의하였다.

기후변화 적응정책의 홍수 피해 저감 효과 분석

서승범 한국수자원공사(K-water) 2023 저널 물 정책·경제 Vol.38 No.-

가뭄 대응을 위한 시나리오 중립 기반의 다원적 의사결정 지원기술 개발 연구

서승범,김지흔,염웅선,이진영,박동혁,김태웅 한국수자원학회 2023 물과 미래(한국수자원학회지) Vol.56 No.7

기후변화에 따른 물수급 분석 기술 최신 연구동향

서승범,이재경,김영오 한국수자원학회 2010 한국수자원학회논문집 Vol.43 No.9

전완부 후골간 동맥 유리피판술을 이용한 안면부 조직 결손 재건 치험례

서승범,이상원,안태황,정성균,김창현,Seo, Seung Bum,Lee, Sang Won,An, Tae Whang,Jung, Sung Gyun,Kim, Chang Hyun 대한미세수술학회 2000 Archives of reconstructive microsurgery Vol.9 No.2

With esthetic concern in the reconstruction of skin and soft tissue defects of face, the use of local flap has been the method of choice. However, when there is extensive tissue loss in the face, local flaps do not provide satisfactory results. The amazing development of microsurgical technique has decreased the percentage of free flap failure, thus making free flap use in reconstruction of facial soft tissue defects. Many free flaps has been applied for reconstruction of face defects. Especially, the radial forearm flap has numerous advantages with which facial reconstruction is made possible. But, its disadvantages are ; the sacrifice of one major artery supplying the hand and donor site complications. In order to circumvent these disadvantages, we employed posterior interosseous artery(PIA) forearm free flap for the reconstruction of the face defects. The posterior interosseous forearm island flap was first described by Zancolli and Angrigiani(1985). Currently, the PIA island flap and free flap have been used for hand reconstructions. The disadvantages of the PIA flap are ; the small caliber of the pedicle, different locations of the perforating branches, and the proximity of the motor branch of the radial nerve. But, its advantages lies in preserving the major artery of the hand, minimal donor site morbidity, and fairly well matched skin texture and color, and that the flap volume is sufficient, not too bulky with convenient handling. By using this flap, we performed 1 case of tumor resection and 1 case of traumatic defect. From our experiences we conclude that it is one of many useful methods in the reconstruction of the skin and soft tissue defects of the face. We also have discussed advantages and some limitations of various free flaps for reconstruction of the face.