• 대한치과교정학회지
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• 제52권5호
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• pp.313-323
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• 2022

Objective: This study aimed to estimate the clinical effects of different types of bone-anchored maxillary protraction devices by using a network meta-analysis. Methods: We searched seven databases for randomized and controlled clinical trials that compared bone-anchored maxillary protraction with tooth-anchored maxillary protraction interventions or untreated groups up to May 2021. After literature selection, data extraction, and quality assessment, we calculated the mean differences, 95% confidence intervals, and surface under the cumulative ranking scores of eleven indicators. Statistical analysis was performed using R statistical software with the GeMTC package based on the Bayesian framework. Results: Six interventions and 667 patients were involved in 18 studies. In comparison with the tooth-anchored groups, the bone-anchored groups showed significantly more increases in Sella-Nasion-Subspinale (°), Subspinale-Nasion-Supramentale(°) and significantly fewer increases in mandibular plane angle and the labial proclination angle of upper incisors. In comparison with the control group, Sella-Nasion-Supramentale(°) decreased without any statistical significance in all treated groups. IMPA (angle of lower incisors and mandibular plane) decreased in groups with facemasks and increased in other groups. Conclusions: Bone-anchored maxillary protraction can promote greater maxillary forward movement and correct the Class III intermaxillary relationship better, in addition to showing less clockwise rotation of mandible and labial proclination of upper incisors. However, strengthening anchorage could not inhibit mandibular growth better and the lingual inclination of lower incisors caused by the treatment is related to the use of a facemask.

• Journal of Korean Society for Atmospheric Environment
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• 제20권E1호
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• pp.29-33
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• 2004

In environmental studies, decisions are often made on the analytical data indicating certain contaminants as being 'detected' or 'non-detectible.' Since detection limits are analytical method specific, one has to first review the concepts and definitions associated with analytical method systems and specifications. In this study, the experimental analytical values for a series of low level standards (for an ionic species) were used as an example to estimate two different method detection limits (MDL). The scores of EPA's MDL and Pallesen's MDL determined by real analytical scores are 0.0575 and 0.0561 mg/L, respectively for our nitrate data. These scores determined by two different MDL models are roughly similar, while there are apparent differences between two methods with respect to statistical and systematical procedure. However, determination of MDL for one's laboratory provides some practical applications which helps to assure one's regulating authorities that one's measured scores are accurate.

• 한국정보처리학회논문지
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• 제3권4호
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• pp.1014-1025
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• 1996

현재 CRT(Cathode-Ray Tube)의 마그네트(Magnet) 생산업체에서 색상제어에 사용 構殷있는 착자기 및 착자검사기는 수동으로 작업 시간이 오래 걸리고 오동작 시킬 우려가 있다. 본 연구에서는 착자와 검사 공정까지를 한 시스템으로 묶은 시스템 장치를 개발하여 전공정을 자동화시켰다. 따라서 본 시스템은 매회 작업 상태를 검사하고 품질의 산포를 정확하게 분석하여 착자 및 착자 상태 검사의 신뢰도를 향상시켜 불량을 없애도록 하였다.

• 품질경영학회지
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• 제47권4호
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• pp.783-793
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• 2019

Purpose: The purpose of this study is to apply the machine and deep learning methodology on error terms which are continuously auto-generated on the sensors with specific time period and prove the improvement effects of power generator prediction diagnosis system by comparing detection ability. Methods: The SVM(Support Vector Machine) and MLP(Multi Layer Perception) learning procedures were applied for predicting the target values and sequentially producing the error terms for confirming the detection improvement effects of suggested application. For checking the effectiveness of suggested procedures, several detection methodologies such as Cusum and EWMA were used for the comparison. Results: The statistical analysis result shows that without noticing the sequential trivial changes on current diagnosis system, suggested approach based on the error term diagnosis is sensing the changes in the very early stages. Conclusion: Using pattern of error terms as a diagnosis tool for the safety control process with SVM and MLP learning procedure, unusual symptoms could be detected earlier than current prediction system. By combining the suggested error term management methodology with current process seems to be meaningful for sustainable safety condition by early detecting the symptoms.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.269-272
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• 2004

The present study used a diagrammatic analysis of 6 sigma quality control and Taguchi method for injection molding process of monitor back-cover, evaluated the influence on the cycle time with part design, mold design, molding process and standardization activity involving design & molding, adopted analysis of sensitivity and effective factors of the part design and molding process conditions for productivity, identified main design molding factors, as critical ones influencing on the quality and productivity, of which is summarized as design guidance. The main contribution factors for cycle time can be sequentially enumerated as follows; hot spot, part thickness, coolant inlet temperature, melt temperature cooling line layout, etc.. As a first step critical factors of the design process of current monitor housing were investigated. And the optimal and better critical factors found in the first step were applied to a new product proving our process was correct. Moldflow software was used for injection molding simulation, and Minitab software for the statistical analysis. Finally, the productivity was increased by about 33 percents for our specific case.

• 품질경영학회지
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• 제34권2호
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• pp.129-135
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• 2006

In the advance of computer technology, it is possible to keep all the related informations for monitoring equipments in control and huge amount of real time manufacturing data in a data base. Thus, the statistical analysis of large data sets with hundreds of thousands observations and hundred of independent variables whose some of values are missing at many observations is needed even though it is a formidable computational task. A tree structured approach to classification is capable of screening important independent variables and their interactions. In a Six Sigma project handling large amount of manufacturing data, one of the goals is to screen vital few variables among trivial many variables. In this paper we have reviewed and summarized CART, C4.5 and CHAID algorithms and proposed a simple method of screening vital few variables by selecting common variables screened by all the three algorithms. Also how to develop a logistics regression model on a large data set is discussed and illustrated through a large finance data set collected by a credit bureau for th purpose of predicting the bankruptcy of the company.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권10호
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• pp.1814-1829
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• 2011

In this paper, we present a model-based video bit rate estimation scheme for reducing the bit rate while maintaining a given target quality in many video streaming services limited by network bandwidth, such as IPTV services. Each item of video content can be stored on a video streaming server and delivered with the estimated bit rate using the proposed scheme, which consists of the following two steps: 1) In the first step, the complexity of each intra-frame in a given item of video content is computed as a frame feature to extract a group of candidate frames with a lot of bits. 2) In the second step, the bit rate of the video content is determined by applying statistical analysis and hypothesis testing to that group. The experimental results show that our scheme can reduce the bit rate by up to 78% with negligible degradation of subjective quality, especially with the low-complexity videos commonly used in IPTV services.

• 대한토목학회논문집
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• 제7권4호
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• pp.61-71
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• 1987

콘크리트의 품질판정기준(品質判定基準)은 재령(材令) 28일(日)의 압축강도(壓縮强度)이지만, 실질적인 품질관리(品質管理)를 위해서는 조기(早期)에 강도(强度)를 파악해야 한다. 콘크리트 강도(强度)를 조기판정(早期判定)하는 방법은 크게 "강도촉진법(强度促進法)"과 굳지 않은 콘크리트의 "분석법(分析法)"이 있으나, 본(本) 연구(硏究)에서는 $70^{\circ}C$의 열수양생법(熱水養生法)으로 다양한 양생방법을 시도하여 기존의 외국기준(外國規準)보다 개선된 방법을 제시하였다. 실험자료의 분석(分析)에 있어서는 각 강도의 변동을 검토함은 물론, 합리적인 추정식(推定式)을 제안하기 위하여 각 강도의 분포(分布)를 고려하고 확률적(確率的) 관계(關係) 및 품질기준(品質基準)의 적합성(適合性)을 검토하였다. 실험결과 촉진강도(促進强度)의 변동은 비교적 작게 나타났으며, 본 연구에서 제안한 대부분의 방법이 좋은 상관성(相關性)을 가지고 있어 유용한 조기판정방법(早期判定方法)으로 판명되었다.

• 한국가스학회지
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• 제11권3호
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• pp.56-63
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• 2007

오늘날 고객의 요구는 보다 더 다양해지고 있고, 시장 환경이 급속히 변화함에 따라 기업의 모든 활동은 고객중심으로 이루어지고 있다. 최근 제품 및 서비스의 품질 향상을 위해 변화혁신 활동을 추진한 기업이 늘어나고 있는 실정이다. 본 연구는 도시가스 공급시설을 효율적으로 보수하기 위하여 6시그마 기법을 이용하여 공급시설 건전성에 영향을 주는 핵심인자를 도출하였으며, Risk 인자는 정량적인 평가를 통하여 시그마 값을 산출하였고, 근본원인 및 해결안을 도출, 새로운 프로세스를 적용하여 통계적 공정관리를 실행하였다. 도시가스 공급시설의 안전관리는 위험을 정량화하여 통계적인 공정관리를 통하여 산포를 줄이고, 품질관리 비용을 제거해서 효율적인 경영관리가 가능하며, 6시그마 이용 기법의 정착과 효율적인 운용의 확산을 통해 과학적인 안전관리가 가능할 것으로 기대된다.

• 대한산업공학회지
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• 제25권4호
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• pp.500-509
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• 1999

In this paper, we consider an optimal routing problem when point-to-point and point-to-multipoint connection traffics are offered in an ATM network. We propose a mathematical model for cost-minimizing configuration of a logical network for a given ATM-based BISDN. Our model is essentially identical to the previous one proposed by Kim(Kim, 1996) which finds a virtual-path configuration where the relevant gains obtainable from the ATM technology such as the statistical multiplexing gain and the switching/control cost-saving gain are optimally traded-off. Unlike the Kim's model, however, ours explicitly considers the VP's QoS(Quality of Service) for more efficient utilization of bandwidth. The problem is a large-scale, nonlinear, and mixed-integer problem. The proposed algorithm is based on the local linearization of equivalent-capacity functions and the relaxation of link capacity constraints. As a result, the problem can be decomposed into moderate-sized shortest path problems, Steiner arborescence problems, and LPs. This fact renders our algorithm a lot faster than the previous nonlinear programming algorithm while the solution quality is maintained, hence application to large-scale network problems.