• 응용통계연구
• /
• 제23권6호
• /
• pp.1147-1156
• /
• 2010

본 논문에서는 비 재생무료교체-수리보증이 종료된 이후의 수리가 가능한 시스템에 대한 교체정책을 제안한다. 이를 위해서, 비 재생무료교체-수리보증을 정의하고, 사용자 측면에서 비 재생무료교체-수리보증이 종료된 이후의 보전모형이 고려된다. 최적의 보전정책을 결정하기 위한 기준으로는 사용자 측면의 단위시간당 기대비용이 고려되고, 보증 기간이 종료된 이후에 발생되는 시스템의 유지비용은 사용자가 모두 지불하게 된다. 즉, 시스템의 운영기간 동안 사용자가 지불하여야 할 비용들이 주어져 있을 때, 비 재생무료교체-수리보증이 종료된 이후의 최적의 보전주기를 결정한다. 마지막으로 본 논문에서 제안된 보존정책을 설명하기 위해서 수치적 예를 살펴본다.

• Communications for Statistical Applications and Methods
• /
• 제18권6호
• /
• pp.697-705
• /
• 2011

본 논문에서는 수리가 가능한 시스템에 대하여 무료 재생교체-비재생수리보증이 종료된 이후의 최적의 교체정책을 제안한다. 이를 위해서, 무료재생교체-비재생수리보증을 정의하고, 사용자 측면에서 무료재생교체-비재생수리보증이 종료된 이후의 보전모형을 고려한다. 최적의 보전정책을 결정하기 위한 기준으로는 사용자 측면의 단위시간당 기대비용을 사용하는데, 이러한 단위시간당 기대비용을 구하기 위해서 사용자측면의 기대순환길이와 총기대비용을 각각 유도한다. 끝으로 본 논문에서 제안된 무료 재생교체-비재생수리 보증이 종료된 이후의 최적의 교체정책을 설명하기 위해서 수치적 예를 살펴본다.

• International Journal of Reliability and Applications
• /
• 제12권1호
• /
• pp.41-48
• /
• 2011

This paper considers the maintenance model suggested by Jung and Park (2010) to adopt the Bayesian approach and obtain an optimal replacement policy following the expiration of NFRRW. As the criteria to determine the optimal maintenance period, we use the expected cost during the life cycle of the system. When the failure times are assumed to follow a Weibull distribution with unknown parameters, we propose an optimal maintenance policy based on the Bayesian approach. Also, we describe the revision of uncertainty about parameters in the light of data observed. Some numerical examples are presented for illustrative purpose.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
• /
• pp.122-124
• /
• 2005

Underground distribution system is a trend due to the successive development of metropolitan area and satellite cities and the environment of the commercial and residential areas. The high quality of electricity, which is related with the minimal outage duration time due to the maintenance work for the underground distribution line, is mandatory. Hence, the construction method and tools for the outage-free maintenance construction have been required for underground distribution system. So far, all the efforts for outage-free maintenance for the underground distribution have been limited only to the survey for foreign countries situation and the theoretical provision; thus, It is required to develop the various construction method and the application tools. Differently from the aerial line, the construction of the underground cable is complicated and the insulation distance between conductor and shield should be maintained in loadmaking/breaking operation, though the apparatus connected with cable is a deadfront type. Also since the apparatus is installed above ground, by-pass of faulted area at busy area needs a variety of high technologies. Therefore, in this these, the authors introduce the development status of the loadbreak connectors, connection facilities, outage-free maintenance system for secondary side, a secondary auxiliary bushing and additional tools so that there can be more progress on this field.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.331-333
• /
• 2001

The flooded type battery is used for solar lighting system. Because the characteristic of flooded type battery is the short life time, the maintenance cost is high. So the using floe fed type battery in this system is inappropriate. The valve regulated lead acid batter(VRLA) is the maintenance free and cycle service purpose. This paper presents the development of control system and monitoring system to applied VRLA battery for maintenance free and long life time in system.

• Journal of the Korean Data and Information Science Society
• /
• 제20권6호
• /
• pp.999-1007
• /
• 2009

본 논문에서는 무료수리보증이 종료된 이후의 최적의 주기적 예방보전정책을 고려한다. 이를 위해서 Wu와 Clements-Croome (2005) 그리고 Jung (2006b)이 제안한 확률적 보전효과를 갖는 두 종류의 예방보전모형을 가정하고자 한다. 이 때, 시스템이 가동되는 동안에 사용자가 지불해야 할 비용이 주어져 있을 때, 단위시간당 기대비용을 유도한다. 그리고 이렇게 구해진 단위시간당 기대비용을 최소화하는 최적의 예방보전 횟수와 예방보전 주기를 결정한다. 끝으로 수치적 예를 통해서 제안된 예방보전정책을 자세히 설명한다.

• 한국철도학회논문집
• /
• 제10권2호
• /
• pp.167-178
• /
• 2007

In general, it is known that the concrete ballast track is possible to reduce a cost of maintenance activities cause of maintenance free by restrictive maintenance in application of track ballast structures. However, if deteriorations and fracture mechanism of a material are considered, proper maintenance activities and repairing are continually required. For the problems, we evaluated an economical efficiency of the gravel ballast and the concrete ballast on a proper level of maintenance activities. As the method based on history path is difficult to obtain sufficient reliabilities cause of an absence of real data for maintenance activities, we chose the delphi survey method by professional group, and we obtained the appropriate index and profiles for maintenance activities. As a result, we founded that effects for cost reduction can be expected by preventive maintenance management, and we proposed economical restrictions and life cycle cost for track ballast structures in a life cycle.

• 국제학술발표논문집
• /
• The 9th International Conference on Construction Engineering and Project Management
• /
• pp.624-631
• /
• 2022

Highway Rest Areas are envisioned to provide an accessible space for rest and parking for travelers, especially those driving a long distance. In addition, modern highway Rest Areas provide many amenities to highway users, including wifi service, picnic tables, litter barrels, running water, public telephones, and sometimes even free coffee. Various studies were conducted in the domain of Rest Area facility design and their operating costs in different states; however, limited studies were conducted on the maintenance costs of these facilities. Therefore, this study's main objective is to compute the annual maintenance cost of Rest Areas in the state of Nevada. This study also analyzes the main cost categories of the maintenance works. The raw cost data of Nevada Rest Area maintenance from 1990 to 2012 were collected from the Nevada Department of Transportation (NDOT). Results show that the maintenance cost fluctuated over the study period; the maintenance cost decreased from 1991 to 2004 and then increased until 2012. The primary cost categories of maintenance work are labor, equipment, and material costs. Among these, labor cost was the largest category with 56 percent of the total maintenance cost, followed by equipment cost and material cost. The findings of this study may help NDOT and other transportation agencies plan their budget for future Rest Area maintenance activities.

• Childhood Kidney Diseases
• /
• 제22권1호
• /
• pp.1-6
• /
• 2018

Rituximab (RTX) is a chimeric monoclonal antibody that inhibits CD20-mediated B-cell proliferation and differentiation. Several studies have examined its use in intractable nephrotic syndrome (NS) with some positive results. However, those studies examined such effects for a short-term period of 1 year, and some patients continued to relapse after a lapse in RTX treatment. Our use of RTX as a maintenance therapy (RTX injection when the CD19 cell count exceeded $100-200/{\mu}L$ before relapse) showed some noticeable efficacy. We used RTX in 19 patients with steroid-dependent NS (SDNS). In 12 patients treated with RTX maintenance therapy, only one relapse occurred. The mean treatment period was $23.4{\pm}12.7months$, and the mean number of RTX administrations was $3.9{\pm}1.6$. The relapse rates were decreased (from 2.68/year to 0.04/year), and the drug-free period also increased (from 22.5 days/year to 357.1 days/year) during maintenance therapy. The other seven patients were treated with one cycle of RTX or additional cycles in case of relapse (non-maintenance therapy). Relapse rates were significantly decreased after RTX treatment (from 1.76/year to 0.96/year, P=0.017). The relapse-free period was $15.55{\pm}7.38$ (range, 5.3-30.7) months. No severe side effects of RTX were found except for a hypersensitivity reaction such as fever and chills during its infusion. In conclusion, RTX is considered an effective and safe option to reduce the relapse rate by a single- or maintenance-interval therapy in SDNS.

• KSBB Journal
• /
• 제14권1호
• /
• pp.91-95
• /
• 1999

P. phosphoreum의 고정화에 있어 중요한 것은 Matrix의 선택이며, Matrix로서 sodium algnate만을 사용하여 고정화하는 것보다는 strontnum chloride를 첨가하였을 때 세포의 bio-iummescence 유지도가 증가하였다. 저장 온도에 따른 bio-iummescence 유지도와 관련하여 -$70^{\circ}C,\;-20^{\circ}C,\;20^{\circ}C$에서 저장한 세포의 경우 저장 1일 후에 급격한 bioluminescence의 감소를 보였으나 $4^{\circ}C$ 에서 저장한 세포는 bioluminescence의 유지도가 15일 이상 이어졌다. 따라서 P. phosphoreum의 bioluminescence 안정성에 있어 가장 좋은 결과를 나타낸 것은 2.5%(W/W)sodium alginate와 0.3M(W/V)strontnum chloride 를 사용하여 고정화한 세포였으며 저장 온도는 $4^{\circ}C$였다.