• 한국생산제조학회지
• /
• 제9권5호
• /
• pp.157-164
• /
• 2000

A machine tool generally has some serious stability problems in the form of tool chatter during the cutting process. Chatter vibration deteriorates the surface finish, reduce tool and machine life, accelerates machine tool system component wear, and may lead to an unacceptable noise sound in the working environment. In this study, the behavior of spectral density of AE signal and principal cutting force signal in order to monitor the chatter vibration in the cutting process has been investigated. From the results, the reliability of proposed monitoring method has been confirmed.

• 한국건설관리학회논문집
• /
• 제6권5호
• /
• pp.139-147
• /
• 2005

During a typical construction project, a contractor nay often find that the time originally available or normally expected to perform its work has been severely reduced. To finish the project by the completion date, the contractor is forced to find a way to speed up the progress of its work to compensate for the reduction in available time. The most frequent initial reaction of contractors to this situation is to increase on-site manpower by working longer time (overtime), adding more workers (overmanning), or implementing shift work (shift work) to increase the rate of progress. The goals of this study were to investigate how these three methods affect labor productivity and to quantify their impact on labor productivity by analyzing real project data collected from sheet metal contractors and mechanical contractors in the US.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
• /
• pp.14-19
• /
• 2000

A machine tool has some serous stability problem in the from of tool chatter during the cutting process. Chatter vibration deteriorates the surface finish, reduce tool and machine life, accelerate machine tool system component wear, and may lead to an unacceptable noise sound in the working environment. In this study, in order to moni색 of the chatter vibration on the cutting process, the behavior of spectral density of AE signal and principal cutting force signal has been investigated. Furthermore, its reliability from obtained the results has been studied to evaluate and confirm the proposed method with the application procedure and the experimental results.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
• /
• pp.33-34
• /
• 2017

The purpose of this case study is to reduce the flaw and reconstruction occur at the level of construction by determining the propriety of estimate and error on a drawing and specification at working design level through case studies of BIM application at the level of design review. As a preliminary to apply BIM technology, it is needed to review the drawing, and then it is required to define BIM range by selecting the section in which construction error occurs frequently except for the type of part that is constructed repeatedly. At the execution level, the drawing is reviewed vertically, horizontally and spatially by proceeding structure and finish modeling on the defined BIM range, and also the propriety of estimate and error on the drawing and specification are examined. We aim to raise the completion rate, improve quality of construction, reduce the cost for construction and shorten period of construction by preparing for the error on the drawing and specification in advance through this review procedures.

• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
• /
• pp.996-998
• /
• 1996

The drum-type hill-drop unit, an important working device of the plastic -film-covered hill planter, can finish filling and separating seed precisely, perforating film and holing , and its seeding depth and spacing are stability . The unit is applied to hole seed many crops, for example, cotton, corn , soybean, etc. The drum-type hill-drop unit(DHU) , the key work unit to the plastic film-covered planter, mainly consists of distributor box , seeding parts, hole forming unit and drum , It can be operated to accomplish seeds distributing, hole forming , plastic film perforating . Moreover , its inner cavity can be used as seed box.

• 한국정밀공학회지
• /
• 제10권1호
• /
• pp.70-76
• /
• 1993

Burnishing, as a micro plastic working, is a finishing process used in conjuction with or in replacement of reaming, honing, lapping, and/or grinding. The tool which is a smooth, round steel ball slightly larger than the bore is pushed through pre-machined hole, leaving a closely controlled finish. The major application of the processes is to improve the geometric and mechanical properties of surface such as (1) dimensional accuracy, (2) surface roughness, (3) bearing ratio, (4) surface hardness, (5) wear resistance, (6) fatigue and corrosion resistance, etc. Therefore, this study carried out some experiments to illustrate the theoretical formula and to investigate surface accuracy (e.g. variation of diameter, surface roughness, bearing ratio) in accordance with the applied burnishing load.

• 한국정밀공학회지
• /
• 제17권9호
• /
• pp.189-195
• /
• 2000

RP techniques have their unique characteristics according to the working principles : star-stepped surface of parts due to layer-by-layer stacking low build speed caused by line-by-line solidification to fish one layer and post processing to improve surface finish etc The objective of this study is to propose a new RP technique Variable Deposition Mnanufacturing (VDM) which can make up for the disadvantages of the existing RP techniques and to develop an apparatus to implement the technique. The proposed process can greatly reduce the build time and improve the surface finish of parts generated. Experiments are carried out to obtain the range of temperature of molten material to maintain its fluidity and to investigate the effect of gas cooling on the preservation of the slopes. Some simple shapes such as a line-shape an S-shape and a circle-shape are fabricated from Ethylene Vinyl Acetatecopolymer(EVA) In order to examine the applicability of VDM to more general shapes a tensile specimen and a yo-yo shape were manufactured by the proposed RP method using EVA material as a trial approach. The current basic study shows a high potential of practical use of the proposed VDM process to prototyping of a general three-dimensional shape.

• 한국건설관리학회논문집
• /
• 제13권5호
• /
• pp.113-124
• /
• 2012

TACT공정관리는 국내의 아파트 마감공사 및 초고층공사에 사용하고 있으나 관련정보가 체계화되지 못해 공사수행에 따른 실적자료의 DB화 및 타 현장에서의 활용이 어렵고, 관련정보를 찾는데 많은 시간이 소요되고 있다. 이러한 문제를 보완하기 위해서는 TACT공정관리에 필요한 공사정보의 과학적이고 정량적인 이해가 요구되며, 실무자가 업무흐름에 따른 요구정보를 쉽게 파악할 수 있는 관리방안이 필요하다. 따라서 본 연구에서는 TACT공정관리 프로세스를 일반적인 공정관리를 기반으로 재설계 하였으며, 전문가 평가를 실시하였다. 본 연구를 통해 실무자의 업무이해도를 증진 시키고 담당자 소속 변경 시 처리절차를 빠른 시간에 파악할 수 있게 함으로써 관련 부서와의 협조 조정과 사업수행에 따른 효율화를 도모할 수 있을 것으로 판단된다.

• 대한인간공학회지
• /
• 제31권1호
• /
• pp.171-176
• /
• 2012

Objective: The goal of this study was to assess work ability of Korean workers in the shipbuilding industry. Background: Old age is associated with inevitable time-dependent losses in physical capabilities. However the maintenance of physical capabilities is essential for continuing independence in old age. The work ability index(WAI) was constructed to reveal how well a worker is able to perform his or her work. Method: The WAI is a kind of survey methods developed to estimate the work capacity of aged workers by the Finish Institute of Occupational Health(FIOH) in 1998. The difference of the WAI between groups in each category was tested using the Kruskal-Wallis test, and the relationship between the WAI and the workers' ages was tested by the Correlation test. Results: This study surveyed 2,709 persons working in the shipbuilding industry in Korea. The average WAI score for all workers was 40.0 denoting a Good Level. Also, workers in the shipbuilding industry had lower work ability, as compared to the results of other industries. The WAI was analyzed for different age groups(${\leq}29$; 30~34; 35~39; 40~44; 45~49; 50~54; ${\geq}55$). The results of Kruskal-Wallis test showed that significant difference was identified on the effect of aging(p<0.05). Conclusion: Advanced countries like the Finland showed decreasing tendency in good and excellent levels as aged, but there was no decreasing tendency in Korean population. The results may be attributable to the general characteristics of Korean society, such as poor social security and burden caused by role of the patriarch. It may bring forth higher work ability in aged population even their physical condition is getting worse. Application: This finding could be used for developing more accurate assessment tool of work ability for working environment.

• 한국건설관리학회:학술대회논문집
• /
• 한국건설관리학회 2003년도 학술대회지
• /
• pp.422-425
• /
• 2003

건축공사의 고층화 추세에 따라 반복공정의 수가 증가하고, 마감공사에서의 관련 공종 수가 증가하여 작업 연속성에 대한 계획 및 공사관리가 중요하게 인식되고 있으며, 이러한 마감공사의 효율적 은용을 위해 각 작업을 일정한 리듬으로 반복되도록 함에 따라 공정의 개선을 이루고자 하는 기법이 택트공정관리이다. 그러나 택트공정관리는 세부공정 및 작업구역에 따른 상이한 시공속도와 이로 인한 선행공정의 작업지연 등 비효율적 요소 때문에 적용에 어려움이 있었다. 따라서 본 연구에서는 작업별 소요시간의 동기화(同期化)를 통한 개선효과를 파악하기 위해 기존의 공동주택 창호공사를 대상으로 작업방식의 세부작업단위 및 작업인원 수를 작업시간의 동기적(同期的)연결 및 최소 요구인원 수를 기준으로 조정한 후, 공기단축 효과를 분석하였다.