• 한국해양공학회지
• /
• 제30권4호
• /
• pp.334-340
• /
• 2016

The combustion chamber of a diesel engine is often exposed to a more serious wear and corrosion environment than other parts of the engine because its temperature increases as a result of using heavy oil of low quality. Therefore, repair and built-up welding methods must be performed on worn or corroded parts of the piston crown, exhaust valve, etc. from an economical point of view. In this study, Inconel 718 filler metal was used in repair welding on the groove of a forged steel specimen for a piston crown, along with built-up welding on the surface of another forged steel specimen. Then, the corrosion characteristics of the weld metal zone for the repair welding and the deposited metal zone for the built-up welding were investigated using electrochemical methods in a 35% H₂SO₄ solution. The deposited metal zone indicated better corrosion resistance than the weld metal zone, showing a nobler corrosion potential, higher impedance, and smaller corrosion current density. It is considered that metal elements with good corrosion resistance were generally included in the filler metal, and these elements were also greatly involved in the deposited meta by built-up welding, whereas the weld metal consisted of metal elements mixed with both the filler metal and base metal elements because of the molten pool produced by the repair welding. Finally, it is considered that the hardness of the weld metal was increased by the repair welding, whereas the built-up welding improved the corrosion resistance of the deposited metal.

• 동력기계공학회지
• /
• 제7권2호
• /
• pp.73-79
• /
• 2003

The present study was aimed at analysing the damage of a used gas turbine bucket after 39,500h of total service. Microstructures and cracks of service-induced bucket were observed. The crack might have initiated from the coating in the bucket surface by thermal fatigue and propagated into the GTD111 base metal. Maximum depth of penetration was 2.7 mm(full penetration) at the leading edge. Crack contains a lot of Cr-,Ti-,Al-oxide which will prohibit filling and wetting of insert metal. Depth and propagation direction of crack were accorded with centrifugal force and temperature distribution in turbine bucket. Present result will provide basic data for repair bonding process.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
• /
• pp.247-248
• /
• 2013

The waterproof construction for walls and floor in the underground parking lot in the construction of the apartment buildings have been excluded to the introduction of the waterproof design until now, because of the shorten construction period and the reduced construction costs. The concrete structures are existed to the joints in the vertical or horizontal parts commonly. In case of cracks, there are generated due to behavior by subsidence and external changing temperature environment. The cracks are generated by the frequent water leaks. So, the repair methods of the water leaks are proposed as the quick micro-cement and the polyacrylic resin in this study.

• 한국국방경영분석학회지
• /
• 제16권1호
• /
• pp.113-129
• /
• 1990

This paper presents the simulation model to decide the mean size of cannibalization aircraft (MSCA) under steady state when an airbase makes use of cannibalization to support the spare parts of an airfleet. In this model, the essential factors such as mission requirements, mission time, failure time, repair time, repair capability, inventory policy, cannivalization rule are considered. The model is constructed with above factors and actual airbase operating rules for a basis. Because of the tangled interdependencies among the each factors, it is inevitable to construct the model by the simulation technique. The mission and support system of the airbase is considered as a closed queueing network with a finite number of unit The troubled aircrafts are repaired in accordance with the priorities that are determined by their repair times. The illustrative example of the model, using the actual data of xx-airbase, is presented. The model would be a useful tool not only to determine the MSCA and the size of scheduled maintenance aircraft but to evaluate the NORS (not operationally ready supply) rate and the availability of an airfleet.

• 한국산업융합학회 논문집
• /
• 제7권1호
• /
• pp.63-68
• /
• 2004

There are a lot of manholes such as for water supply, sewage, telecommunication cable, traffic sign, electricity supply, and rainwater, etc. Conventional manholes installed on a road are impossible to adjust height, so that they should be entirely excavated to reinstall or repair. This entire excavation of a manhole causes too much time-consuming work, waste of resources, and obstruction of traffic. In this study, in order to solve the above mentioned problems, a cover, outer and inner parts of a manhole are integrated by gear-shaped parts located between outer and inner parts of a manhole. Mechanical design is performed to determine dimension of gear-shaped parts by Taguchi orthogonal array table. Cast molds for a gear-shaped manhole are also manufactured.

• 산업경영시스템학회지
• /
• 제30권3호
• /
• pp.117-126
• /
• 2007

It has been a major issue to repair the broken system quickly for improvement of productivity and utilization. Generally, high utilization of system requires the high amount of spare parts in inventory and inventory cost. Therefore, it is necessary to determine the proper amount of inventory with regard to utilization of system. This study designs a methodology for determining the proper amount of inventory level in a two-echelon spare parts distribution system. The requirements are to satisfy proper customer demands at a distribution center and to maintain over the utilization of the whole system at customers. This methodology minimizes total inventory investment at a distribution center and customers.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.710-715
• /
• 2004

There are a lot of manholes such as for water supply, sewage, telecommunication cable, traffic sign, electricity supply, and rainwater, etc. Conventional manholes installed on a road are impossible to adjust height, so that they should be entirely excavated to reinstall or repair. This entire excavation of a manhole causes too much time-consuming work, waste of resources, and obstruction of traffic. In this study, in order to solve the above mentioned problems, a cover, outer and inner parts of a manhole are integrated by gear-shaped parts located between outer and inner parts of a manhole. Mechanical design is performed to determine dimension of gear-shaped parts by Taguchi orthogonal array table. Cast molds for a gear-shaped manhole are also manufactured.

• 산업경영시스템학회지
• /
• 제38권1호
• /
• pp.110-117
• /
• 2015

Spare part management is very important to products that have large number of parts and long lifecycle such as automobile and aircraft. Supply chain must support immediate procurement for repair. However, it is not easy to handle spare parts efficiently due to huge stock keeping units. Qualified forecasting is the basis for the supply chain to achieve the goal. In this paper, we propose an agent based modeling approach that can deal with various factors simultaneously without mathematical modeling. Simulation results show that the proposed method is reasonable to describe demand generation process, and consequently, to forecast demand of spare parts in long-term perspective.

• 한국의류학회지
• /
• 제31권2호
• /
• pp.308-318
• /
• 2007

This study aims to survey the satisfaction level with the fit of ready-made suits(jackets and pants) among adult males and thereby to show its differences by the age group and body type. The respondents to the questionnaire survey were 465 males, aged 20 through 59 years. The conclusions are as follows: 1. The average satisfaction level for the fit of each item ranged from 2.65 to 3.57, with the higher level found in jackets than in pants, and also in circumference parts than in length parts 2. The satisfaction level for the fit by the age of adult males showed inter-group differences in the parts of jacket length, sleeve length, shoulder width, sleeve openings, and sleeve band width for jackets; and pant length of pants. 3. The satisfaction level for the fit by the body type of adult males indicated into-group differences in chest circumference of jackets only. 4. The satisfaction level for the fit, with the exclusion of the age and body type relationship showed that adult males are affected more by the age than by the body type. 5. In the repair frequency by the item, pants(45.6%) showed a higher level than jackets(24.7%). The parts with a high repair level by the item were jacket length(8.4%) and steeve length(19.8%) for jackets; and pant length(42.4%) and waist circumference(8.4%) for pants.

• 대한방사선치료학회지
• /
• 제6권1호
• /
• pp.21-30
• /
• 1994

To analyze the states of operation of radiotherapy facilities in the period from 1979 to 1992 and to get the base for efficient operation and maintenance of the radiotherapy facilities. Data on the records of annual number of patients operated by each facility; span of suspension of operation, the cost and span of repairing, and parts of oui-of-order in the period from 1979 to 1992 were analyzed. We made a comparative analysis of average annual number of patients, annual span of the suspension of operation, annual cost ratio of repair, span of repairing per break down, and total number of broken parts. We could get following annual number of patients(day), span of the suspension of span ($\%$)(day). annual cost ratio fo repair($\%$), span of repairing per break down(Min-Max, day), and number of broken parts from this analysis. 1. Cobalt unit (Picker C-9) : 10,389(43), 0.4(0.83) 0.07, 1hr-2, 3 2. Linac(Clinac 6/100) : 11,492(50), 4.0(9.57), 0.98, 1hr-30, 12 3. Linac(Clinac 18) : 9.115(44), 12.7(30.5), 3.54, 1hr-108. 41 4. Simulator(Picker Ther-X) : 2,017(9), 0.51(1.3), 0.24, 1hr-2, 7 5. RTP(Capentec Cap-plan) : 528(2), 0.4(0.93), - hrs, - The conclusion obtained from statistical analysis above are as follows. 1. The rate of operation of Cobalt unit($99.6\%$) was higher that of Linear Accelerators ($87.3\%$). The rates operation of Simulator and RTP computer were very close to that of Cobalt unit. 2. In order to raise up the working ratio of accelerator. it is desirable that we keep our engineer to learn a sufficient technical skill and the equipment agent to stock sufficient spare parts. 3. In order to maintain Linear Accelerator efficiently, it is desirable to have annually $2.3\%$ of the purchase price of equiment for repairing.