• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.1
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• pp.92-97
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• 2007

This study was carried out to minimize the lifting force and to design the slim sized frame of a height adjustment mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment as well as to achieve much slimmer frame for the pedestal. A tolerance analysis of 6 sigma was applied to achieve smooth lift at design stage not to change the tolerance specification of gap several times in a roller type of lifting mechanism at mass production stage. The specification of minimum gap and the target of production yield ratio were agreed with a quality team before tooling. A DFSS simulation on drawings had been done with reasonable tolerance and achievable standard deviation(${\sigma}$) several times until the target specification of gap and yield ratio was met. Once tolerance and deviation(${\sigma}$) were fixed tooling start was done successfully. A CAE method was applied to achieve a slim design. Design parameters were frozen when those parameters matched the reference strength data of standard model. Through those tolerance analysis and CAE simulation the number of tool modification was reduced and production yield ratio was raised up without arguing quality specification at production stage in the end.

• Korean Journal of Oriental Medicine
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• v.16 no.3
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• pp.135-140
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• 2010

The usefulness of constitutional diagnoses based on skin measurements has been established in oriental medicine. According to Sasang constitutional medicine, humans can be distinguished based on properties of skin's friction, thickness and elasticity. To quantify and standardize skin diagnosis, the present study designed an equipment for measuring skin elasticity of hand. But there were some noises in measuring skin elasticity such as measurement method, environment, operator and conditions of patient. So we considered a six sigma project for reducing the measurement errors. The project was followed to discipline process of five macro phases: Define, Measure, Analyze, Improve and Control(DMAIC). So, we could find the major factors which should be controled for stabilizing measurement system and we revised the SOP(Standard Operating Procedure) of the skin elasticity measurement.

• The Korean Journal of Applied Statistics
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• v.28 no.6
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• pp.1257-1273
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• 2015

The development process of Embedded Software (SW) is gathering interest due to the increased importance of SW in mobile products. According to tough competition and the growing size of the Embedded SW, there is a demand for a new effective way to improve the SW development process, based on customer and market quality aspects, rather than focusing on defect removals in individual SW modules. We review 103 SW improvement projects from the area of mobile phones in order to check the effectiveness of Six Sigma which is the standard for the process improvement statistical tools and methods.

• Korean Journal of Animal Reproduction
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• v.21 no.2
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• pp.95-102
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• 1997

The studies on the carried out to investigate the effective concentration of cryoprotectant agents and sucrose by one-step straw method of bovine embryos. The follicular oocytes were cultured in TCM-199 medium containing 10 IU/ml PMSG(Sigma, USA), 10 IU/ml hCG(Sigma, USA), 1$\mu\textrm{g}$/ml $\beta$-estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% CO2 in air at 38.5$^{\circ}C$ and then matured oocytes were again cultured for 12~18 hrs with motile capacitated sperm by preincubation of heparin. The bovine embryos following dehydration by cryoprotective agents and various concentrations of sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water. Survival and in vitro developmental rate was defined as devellpmental rate on in vitro culture or FDA-test. The results are smmarized as followes : 1. The high in vitro developmental rates of bovine frozen embryos after rapidly thawed in freezing medium was attained 2.0M glycerol, 2.0M DMSO, 1M or 2.0M propanediol. 2. The high in vitro developmental rates of bovine frozen embryos after rapidly thawed in freezing medium was obtained single cryoprotectant(6.7~17.4%) than mixed cryoprotectants(6.7~16.7%). 3. In vitro developmental rate of bovine embryos after rapid frozen-thawing in the freezing medium added 0.25M and 0.50M sucrose were higher cleavage rate than those of sucrose concentration of 0.75M and 1.00M. 4. The freezing methods on in vitro developemental rates of bovine embryos was attained slow freezing method(9.70~15.6%) higher than rapid freezing method(9.4~13.3%).

• The Korean Journal of Applied Statistics
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• v.23 no.6
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• pp.1035-1045
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• 2010

Products and/or services should be objectively verified in terms of the technological and use-conditional considerations before entering a market. Every organization or company tries to find the better procedure and method for checking the core needs of customers based on their experience in the market and looks for continuous ways to evaluate the power of products and services(PoP). They also prefer the overall evaluation of indices that could reflect various customer needs, rather than a separate evaluation index for each characteristic of the product or service. S. Ko (2008) proposes a Multi-characteristics Sigma Level(MSL) that can simultaneously evaluate many characteristics of a product or service. In this research, using MSL and a new Blue Ocean Index(BOI), an application of NPS, mobile phone field test is considered from a practical and statistical point of view.

• International Journal of Quality Innovation
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• v.10 no.1
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• pp.1-23
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• 2009

Face the process yield rate improvements of motherboard, although general enterprises finish deployment goal of each functions by overall quality managements, through quality improvement methods, industry engineering methods, plan-do-check-act (PDCA) methods and other improvement solutions, but it is only can be improved partially and unable to enhance the yield rate of product to the target. It only can takes one step ahead to enhance the process yield rate of motherboard with six sigma ($6{\sigma}$) overall DMAIC process and tactics. This research aimed to use six sigma quality improvement tactics by DMAIC systematic procedure and tactics, and find the key factors that effect to the process yield rate of surface mount technology. It also identified the keys input and process and output index to satisfy customer requirements and internal process index. The results showed that the major effective factors by fishbone and process failure modes and effects analysis (PFMEA). If the index of input and output that can be quantified, the optimum parameter can be found through design of experiment to ensure that the process is stable. If the factor of input and output that cannot be quantified, we found out the effective countermeasure by Mind_Mapping, make sure whole processes can be controlled stably, to reach the high product quality and enhance the customer satisfaction.

• Korean Journal of Oriental Medicine
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• v.12 no.2 s.17
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• pp.85-92
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• 2006

Pulse is one of the basic diagnostic information of TKM(Traditional Korean Medicine). To quantify and standardize pulse diagnosis, we had collected an amount of clinical data from May 2005 by using newly developed pulse analyzer. But there were many noises in pulse wave according to measuring method, environment, operator and condition of patient. So some data can’t be included for analyzing diagnosis. To reduce noises from measuring pulse and to collect reliable pulse wave data, we made the process map of measuring method and applied six sigma project. With this we can improved the method of measuring pulse wave in collecting clinical data. The project follows a disciplined process of five macro phases: define, measure, analyze, improve and control (DMAIC). A process map and C-E diagram are used to identify process input and output variables. The major input variables are selected by using C&E matrix, and process map is developed by analyzing input variables. And the optimum process conditions are going to be controled to avoid in increasing loss of collecting pulse wave data.

• Proceedings of the IEEK Conference
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• summer
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• pp.199-203
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• 2004

In this paper, we only describe the digital block of two-channel 18-bit analog-to-digital (A/D) converter employing sigma-delta method and xl28 decimation. The device contains two fourth comb filters with 1-bit input from sigma­delta modulator. each followed by a digital half band FIR(Finite Impulse Response) filters. The external analog sigma-delta modulators are sampled at 6.144MHz and the digital words are output at 48kHz. The fourth-order comb filter has designed 3 types of ways for optimal power consumption and signal-to-noise ratio. The following 3 digital filters are designed with 12tap, 22tap and 116tap to meet the specification. These filters eliminate images of the base band audio signal that exist at multiples of the input sample rate. We also designed these filters with 8bit and 16bit filter coefficient to analysis signal-to-noise ratio and hardware complexity. It also included digital output interface block for I2S serial data protocol, test circuit and internal input vector generator. It is fabricated with 0.35um HYNIX standard CMOS cell library with 3.3V supply voltage and the chip size is 2000um by 2000um. The function and the performance have been verified using Verilog XL logic simulator and Matlab tool.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.199-202
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• 2005

In this paper, the six sigma scheme is employed together with the rigid-viscoplastic finite element method to obtain the optimal metal flow lines in hot press forging. In general, the six sigma process is consisted of following five steps : define, measure, analyze, improve and control. Each step Is investigated in detail to meet customer's requirements through improvement of product quality. A forging simulator, AFDEX-2D, is used for analysis of the metal flow lines of a multi-stage hot forging process under various conditions of major factors, determined at each step of the six sigma process. The analyzed results are examined in order to reveal the effects of major factors on the metal flow lines and the formed shapes. The effects are used to find an optimal process and the optimal process with die is devised and tested. The comparison between required metal flow lines and experiments shows that the approach is effective for optimal process in hot forging design considering metal flow lines.

• Journal of the Korea Safety Management & Science
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• v.24 no.3
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• pp.93-103
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• 2022

This study investigated the method of continuous improvement of small-medium company production processes through POSCO's QSS(Quick Six Sigma) activities. QSS is a field operation technique that encompasses the advantages of Six Sigma, TPS(Toyota Production System), TQM (Total Quality Management), and IE(Industrial Engineering). Through this, POSCO not only encourages activities centered on related small and medium-sized partners, etc., but is also expected to contribute to the continuous improvement of the company's own production process through QSS activities. In this study, rather than unconditionally carrying out activities according to the needs of large companies, the research is to help the continuous improvement of the actual production process of small and medium-sized enterprises by effectively applying and spreading QSS activities in consideration of the characteristics and environment of the company. For this purpose, empirical research is conducted on the process improvement activities and QSS activities of company Y, which has less than 100 assembly and production quality and inspection processes among SMEs. The changes in the production process improvement of SMEs through the application of the final QSS were investigated through empirical studies.