• Architectural research
• /
• v.15 no.3
• /
• pp.167-174
• /
• 2013

Due to increasing competition of construction companies, it is required to optimize the management of construction projects and "lean" concepts are rapidly spreaded in construction industry. Steel work accounts for a large proportion in construction work, and a variety of attempts to efficiently perform steel work has currently made. And since rebar (Engineer-to-Order) can be engineered through design once order is placed, it gives the great impact on construction, thus, entire management is required. The purpose of this study is to present the method to increase the efficiency of field processing method of steel work in terms of lean construction. Once we examine process of steel work and identify the flow, we would like to analyze which processes should be improved through value analysis approach and present the improvement plans. Also, this study examines cases of field processing and factory processing, and it identifies the waste factors in the procurement process. Finally, this study would like to present the result of analysis from the perspectives of value. The rebar delivery process is divided into several steps and the duration of every step is surveyed. Using duration data, VAT (Value added time) can be calculated for analyzing the efficiency of the process.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.314-319
• /
• 2003

The concept of lean-premixed combustion in gas turbine combustor operation has become a standard in recent years as an effective means to meet stringent enviromental standards on NOx emissions. The combustion characteristics of 75 kW class lean premixed combustor were investigated at the conditions of high temperature and ambient pressure. The exit temperature and emissions of CO and NOx were measured at the center of exit plane. The high temperature air of $550K{\sim}650K$ was supplied through air preheater. As expected, experimental results indicate that NOx emission was increased and CO emission was decreased by increasing inlet air temperature. But CO emission measured at the center of exit plane was increased because of the non-uniform radial direction profiles. The Semi-Empirical Correlation method was applied to obtain the design point emissions of NOx and CO. Also the flame temperature, CO and NOx emissions were measured along the centerline of liner at 650K inlet air temperature to determine the position of dilution holes.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2006.11a
• /
• pp.221-228
• /
• 2006

To reform and improve the productivity of construction industry, 1) it should be encouraged to improve the construction production process and 2) it is required to enhance reliability of construction information based on the systematic thinking process. To promote the information reliability created during construction production process, Lean Construction Research Center(LRC2) is developing a supporting system to improve processes of design/supply/construction phase, functioning to efficiently manage the information created at each phase and developing a web based construction information system that provides result management/decision making support/knowledge based information services.

• Journal of the Korean Society of Combustion
• /
• v.20 no.1
• /
• pp.32-42
• /
• 2015

The combustion instability was experimentally investigated in model gas turbine combustor with dual swirl burner. When such instability occurs, a strong coupling between pressure oscillation and unsteady heat release excites a self-sustained acoustic wave which results in a loud sound, and can even cause fatal damage to the combustor and entire system. In present study, to understand the combustion instability with a premixed mixture, the detailed periods of pressure and heat release data in unstable flame mode were investigated by various measurement methods at relatively rich condition and lean condition near flammable limits. Also, to prepare the utilization of synthetic natural gas (SNG) fuel in gas turbine system, an investigation was conducted using a simulated SNG including methane as a reference fuel to examine the effects of $H_2$ content on flame stability. These results provide that the instability due to flash-back behaviour like CIVB phenomenon occurred at rich condition, while the repetition of relighting and extinction caused the oscillation of lean condition near flammable limit. From the analysis of $H_2$ content effects, it is also confirmed that the instability frequency is proportional to the laminar burning velocity at both rich and lean condition.

• Journal of Biosystems Engineering
• /
• v.39 no.3
• /
• pp.174-183
• /
• 2014

Purpose: A robust, efficient auto-grading computer vision system for meat carcasses is in high demand by researchers all over the world. In this paper, we discuss our study, in which we developed a system to speed up line processing and provide reliable results for pork grading, comparing the results of our algorithms with visual human subjectivity measurements. Methods: We differentiated fat and lean using an entropic correlation algorithm. We also developed a self-designed robust segmentation algorithm that successfully segmented several porkcut samples; this algorithm can help to eliminate the current issues associated with autothresholding. Results: In this study, we carefully considered the key step of autoextracting lean tissue. We introduced a self-proposed scheme and implemented it in over 200 pork-cut samples. The accuracy and computation time were acceptable, showing excellent potential for use in online commercial systems. Conclusions: This paper summarizes the main results reported in recent application studies, which include modifying and smoothing the lean area of pork-cut sections of commercial fresh pork by human experts for an auto-grading process. The developed algorithms were implemented in a prototype mobile processing unit, which can be implemented at the pork processing site.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.4
• /
• pp.98-104
• /
• 2014

The technologies employing spray-guided type combustion system for ultra-lean combustion direct injection engine is focused as a promising technology for satisfying emission regulations and improving fuel economy. In the present study, control and design optimization of lean-burn LPG direct injection engine was carried out with control strategy and injection position changes. Inter-injection spark ignition strategy was applied and the effect of the strategy was assessed at relatively higher load operation condition than previous researches. In order to create richer mixture in the vicinity of spark plug electrode, relative distance between the dead-end of injector and the electrode of spark plug was changed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.4
• /
• pp.1-11
• /
• 2004

Combustion and fuel distribution characteristics of heavy duty engine with the liquid phase LPG injection(LPLI) were studied in a single cylinder engine, Swirl ratio were varied between 1.2, 2.3, and 3.4 following Ricardo swirl number(Rs) definition, Rs=2.3 showed the best results with lower cycle-by-cycle variation and shorter burning duration in the lean region while strong swirl(Rs=3.4) made these worse for combustion enhancement. Excessive swirl resulted in reverse effects due to high heat transfer and initial flame kernel quenching. Fuel injection timings were categorized with open valve injection(OVI) and closed valve injection(CVI). Open valve injection showed shorter combustion duration and extended lean limit. The formation of rich mixture in the spark plug vicinity was achieved by open valve injection. With higher swirl strength(Rs=3.4) and open valve injection, the cloud of fuel followed the flow direction and the radial air/fuel mixing was limited by strong swirl flow. It was expected that axial stratification was maintained with open-valve injection if the radial component of the swirling motion was stronger than the axial components. The axial fuel stratification and concentration were sensitive to fuel injection timing in case of Rs=3.4 while those were relatively independent of the injection timing in case of Rs=2.3.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.29 no.3
• /
• pp.77-96
• /
• 2011

Most of all manufacturing industries are pursuing the manufacturing process innovation through the production process automation but the printing industry still does not get out of the analog ways of the entire process compared the entire manufacturing industry. Today, many printing enterprises have the difficulties by the short for delivery, multi-item small amount printing, high quality, rise in raw material cost, drop in receiving order cost, and etc. The printing industry can get over these difficulties and issues by implementing the compact workflow line, merge with the others, automatization and networking, minimization of the repetitive operation, efficiency of the working process, optimization of the operators' value creation, minimization of cost and materials and fast make-ready. The object of this thesis establishes the experimental data and study cases applicable in the printing industry by having high labor productivity and work in line with printing industry processes through "lean printing system".

• The Journal of Korean Academy of Prosthodontics
• /
• v.55 no.1
• /
• pp.32-37
• /
• 2017

In this case report, an alternative impression technique for fabricating removable partial dentures was used in a patient with very few remaining teeth. In this technique, an individual tray was made on the cast, which was made by relining interim denture and taking overimpression with irreversible hydrocolloid according to McLean's functional impression concept. This method showed the following advantages: the no need for border molding with modeling compound, time saving for denture impression without overextension and accurate seating of the individual tray.

• Journal of ILASS-Korea
• /
• v.9 no.2
• /
• pp.9-17
• /
• 2004

The performance characteristics of lean burn system in gasoline engine are mainly affected by the air-fuel mixture in cylinder, gas exchange process of manifold system, exhaust emission of engine, and the electronic engine control system. In order to obtain the effect of performance factors on the optimum conditions of lean burn engine, this study deal with the behavior of mixture formation, gas flow characteristics of air, flow and evaporation analysis of spray droplet in cylinder, vaporization and burning characteristics of lean mixture in the engine, and the control performance of electronic engine control system. The optimum flow conditions were investigated with the swirl and tumble flows in the combustion chamber with swirl control valve. The performance characteristics and optimum condition of flow field in intake system were analyzed by the investigation of inlet flow of air and combustion stabilization on cylinder.