• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
• /
• pp.89-94
• /
• 1997

As the reinforced concrete structures are aged, repair and rehabilitation materials and techniques have ben developed. However, most of the repair materials and methods are imported from abroad and theoretical study and repairing techniques are also not well established yet. A specification for quality of repair materials should be established, in order to secure the stability and to improve the serviceability of the repaired structures. In this study, long term properties of repair materials such as thermal expansion coefficient, hardening shrinkage, creep, and chemical resistance have been tested. The material properties shows to be affected many actors such as curing period, temperatures, relative humidity, and etc. The repair material should be selected by considering the cause and shape of the defects, mix properties, workability, quality control of construction, and etc.

• International Journal of Reliability and Applications
• /
• 제15권1호
• /
• pp.51-64
• /
• 2014

This paper develops a warranty cost model for complex systems with imperfect repair within a warranty period by addressing a practical case that the first inter-failure interval is longer than any other inter-failure intervals. The product is in its best condition before the first failure if repair is imperfect. After the imperfect repair, other inter-failure intervals which are explained by renewal processes, are stochastically smaller than the first inter-failure interval. Based on this idea, we suggest the failure-interval-failure-criterion model. In this model, we consider two random variables, X and Y where X represents failure intervals and Y represents failure criterion. We also obtain the distribution of the number of failures and conduct the warranty cost analysis. We investigate different types of warranty cost models, reliabilities and other measures for various systems including series-parallel configurations. Several numerical examples are discussed to demonstrate the applicability of the methodologies derived in the paper.

• 한국국방경영분석학회지
• /
• 제18권2호
• /
• pp.114-125
• /
• 1992

A policy of periodic replacement with minimal repair at failure is considered for a complex system. Under such a policy the system is replaced at periodic times. iT(i=1,2, $\ldots$), while minimal repair is performed at any intervening system failures. The cost of the j-th minimal repair to the component which fails at age t is g(C(t). $c_j$ (t)), where C(t) is the age-dependent random part, $c_j$(t) is the deterministic part which depends on the age and the number of the minimal repair to the component, and g is a positive nondecreasing continuous function. The cost of replacement is expensive when the number of failures occurring in (0. T) is greater than a threshold level. The problem of determining the optimal replacement period, $T^{\ast}$, which minimizes the total expected cost per unit time over an infinite time horizon is considered. Various special cases are considered.

• 산업경영시스템학회지
• /
• 제19권39호
• /
• pp.89-98
• /
• 1996

This paper is concerned with cost analysis model in free -replacement policy under the periodic maintenance policy The free-replacement policy with minimal repairable item is considered as follows; in a manufacturer's view point operating unit is periodically replaced, if a failure occurs between minimal repair and periodic maintenance time, unit is remained in a failure condition. Also unit undergoes minimal repair at failures in minimal-repair interval. Then total expected cost per unit time is calculated according to maintenance period Tin a viewpoint of consumer's. The expected costs are included repair cost and usage cost: operating, fixed, minimal repair and loss cost. Numerical example is shown in which failure time of item has beta distribution.

• Clinics in Shoulder and Elbow
• /
• 제7권1호
• /
• pp.30-34
• /
• 2004

Purpose: To report our experience of treatment of rotator cuff tear and evaluate the mid-term outcome. Materials and Methods: We have performed 50 cases of mini-open rotator cuff repair from March 1996 to March 1999. Male to female ratio was 34：16, the average age 46.5(23∼57) years old, mean follow-up period was 78(62∼93) months. All-arthroscopic repair and open repair cases were excluded. Mean symptomatic period was 12.5(6∼38) months, operation was indicated in cases of no improvement by 6 months of conservative management. Preoperative simple radiographs and Magnetic resonance arthrography were obtained in all cases. We also observed the inflammation, synovitis, thickness of tear and associated pathology intraoperatively. We evaluated pain, function, and range of motion by UCLA score. Results: Overall UCLA score was mean 29.5 points. Excellent 25, good 18, poor 7 cases. Mean pain score was improved 2.6 to 7.5, 44 cases(88%) were improved and 6 cases(12%) were not improved. Mean functional score was improved 3.4 to 8.5, and activity at follow up, 25 cases(50%) were same, 8 cases(14%) were above, 17 cases(34%) were below compared with preoperative level. Mean active forward flexion was preoperative 112° to postoperative 160°, forward flexion strength was improved 3.8 to 4.7. 43 cases(86%) of patients were satisfied at the result, 7 cases(14%) were not satisfied or aggravated. Results: Mini-open rotator cuff repair was effective method in treating rotator cuff tear.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제44권4호
• /
• pp.159-166
• /
• 2018

Objectives: The aim of the study was to compare wound healing complications following the use of either absorbable or non-absorbable sutures for skin closure in cleft lip repair. Materials and Methods: This was a randomized controlled trial conducted at the Department of Oral and Maxillofacial Surgery, Lagos University Teaching Hospital, Idi Araba, Lagos State, Nigeria. Sixty subjects who required either primary or secondary cleft lip repair and satisfied all the inclusion criteria were recruited and randomized into two groups (Vicryl group or Nylon group). The surgical wounds in all subjects were examined on 3rd, 7th, and 14th postoperative days (POD) for presence or absence of tissue reactivity, wound dehiscence, and local wound infection. Results: Hemorrhage, tissue reactivity, wound dehiscence, and local wound infection were identified as wound healing complications following cleft lip repair. The incidence of postoperative wound healing complications on POD3 was 33.3%. Tissue reactivity was more common throughout the evaluation period with the use of an absorbable (Vicryl) suture compared to a non-absorbable (Nylon) suture, although the difference was statistically significant only on POD7 (P=0.002). There were no significant differences in the incidences of wound dehiscence and infection between the two groups throughout the observation period. Conclusion: There were no statistically significant differences in the incidences of wound dehiscence and surgical site wound infection following the use of either Vicryl or Nylon for skin closure during cleft lip repair. However, more cases of tissue reactivity were recorded in the Vicryl group than in the Nylon group on POD7. Particular attention must be paid to detect the occurrence of wound healing complications, most especially tissue reactivity, whenever a Vicryl suture is used for skin closure in cleft lip repair.

• Journal of Chest Surgery
• /
• 제34권10호
• /
• pp.733-744
• /
• 2001

배경: 대동맥 축착증과 심실중격결손이 동반된 환아의 적절한 치료 방침에 대해서는 이견이 많다. 본 연구는 생후 6개월 이하의 환아에서 대동맥 축착증과 심실중격결손의 일타 완전교정 결과 및 수술방법에 따른 대동맥 축착증의 재발에 대해 알아보고자 하였다. 대상 및 방법: 1995년 1월부터 2000년 12월가지 본원에서 대동맥 축착증과 심실중격결손으로 일차 완전교정을 시행받은 생후 6개월 이하의 환아 33명을 대상으로 후향적으로 조사하였다. 환아의 평균 연령과 체중은 각각 54$\pm$37일(12일~171일)과 3.9$\pm$1.1kg(1.5~6kg)이었다. 대동맥 축착 고정은 연구 초기에는 저체온하 완전순환정지하에서 시행하였으며 최근에는 순환정지없이 무명동맥을 통한 국소 뇌관류 상태에서 시행하였다. 축착증 교정 방법은 초기에는 Extended cad-to-end anastomosis(EEEA;n=16)와 Extended side-to-side anastomosis(ESSA;n=2)를, 최근에는 Extended end-to-sidc anasto mosis(EESA;n=15)를 이용하였다 심실중격결손은 초기 16명에서는 Dacron을, 최근 17명에서는 자가 심낭편을 이용하여 폐쇄하였다. 대동맥궁 발육부전은 29명(88%)에서 있었으며 원위부 발육부전 18명, 완전형 5명, 그리고 복잡형은 6명이었다.

• Archives of Plastic Surgery
• /
• 제40권5호
• /
• pp.584-588
• /
• 2013

Background The ability to achieve a long-term, stricture-free urethral repair is one of the ongoing challenges of reconstructive urologic surgery. A successful initial repair is critical, as repeat procedures are difficult, owing to distortion, scarring, and short urethral stumps. Methods We describe a technique in which the gracilis muscle flap is laid on or wrapped around the urethral repair site to provide a well-vascularised soft tissue reinforcement for urethral repair. This technique promotes vascular induction, whereby a new blood supply is introduced to the repair site to improve the outcome of urethral repair or anastomotic urethroplasty. The surface contact between the muscle flap and the repair site is enhanced by the use of fibrin glue to improve adherence and promote inosculation and healing. We employed this technique in 4 patients with different urethral defects. Results After a follow-up period of 32 to 108 months, all of the urethral repairs were successful without complications. Conclusions Our results suggest that the use of a gracilis muscle flap to vascularise urethral repairs can improve the outcome of challenging urethral repairs.

• 한국전기전자재료학회논문지
• /
• 제13권4호
• /
• pp.273-279
• /
• 2000

Electrical repair method which has replaced laser repair method can replace defective cell by redundancy’s in the redundancy scheme of conventional high density memory. This electrical repair circuit consists of the antifuse program/read/latch circuits, a clock generator a negative voltage generator a power-up pulse circuit a special address mux and etc. The measured program voltage of made antifuses was 7.2~7.5V and the resistance of programmed antifuses was below 500 Ω. The period of clock generator was about 30 ns. The output voltage of a negative voltage generator was about 4.3 V and the current capacity was maximum 825 $mutextrm{A}$. An antifuse was programmed using by the electric potential difference between supply-voltage (3.3 V) and output voltage generator. The output pulse width of a power-up pulse circuit was 30 ns ~ 1$mutextrm{s}$ with the variation of power-up time. The programmed antifuse resistance required below 44 ㏀ from the simulation of antifuse program/read/latch circuit. Therefore the electrical repair circuit behaved safely and the yield of high densitymemory will be increased by using the circuit.

• Steel and Composite Structures
• /
• 제9권2호
• /
• pp.103-118
• /
• 2009

It has been reported that more than thirty five percent of steel bridges in the USA are structurally deficient because of structural degradations. The degraded structures need either full replacement or rehabilitation such that they are able to provide the required services for a longer period of time. The cost for repair in most cases is far less than the cost of replacement. Moreover, repair method generally takes less time than replacement and also reduces service interruption time. Modern advanced composites have been used in aerospace and automotive fields since World War II. In the recent past, because of the high strength-to-weight ratio and high stiffness-to-weight ratio, these composite materials have been introduced to civil engineering infrastructures primarily for repair and rehabilitation of concrete structures. However, only a few preliminary studies on repair of corroded steel structures using theses composite materials are reported in the literature available in the public domain. Thus, in this study, a series of laboratory tests was undertaken to evaluate the effectiveness of this repair method using carbon fiber reinforced polymer composite. The paper discusses the test method and test results obtained from these tests.