• 산업경영시스템학회지
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• 제15권26호
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• pp.77-84
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• 1992

This paper constructs Croup Technology process-based learning curve model adjusted to a Group Technology environment which accounts for shared learning that occurs when multiple products utilize some of the same process steps. Through this constructed model, the estimated times and productivity of labor calculated by the Group Technology process-based learning curve model are compared with those generated by employing product-based 1 earning curve model. For sensitivity analysis of the model, the impact of learning rate and the ordered production quantity on the ratio differences between Group Technology process-based learning curve model and product-based learning curve model are examined. These results indicate the critical importance of employing Group Technology process-based learning curve model when a process spans multiple products.

• 산업경영시스템학회지
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• 제5권6호
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• pp.69-78
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• 1982

Traditional CVP (Cost-Volume-Profit) analysis employs linear cost and revenue functions within some specified time period and range of operations. Therefore CVP analysis is assumption of constant labor productivity. The use of linear cost functions implicity assumes, among other things, that firm's labor force is either a homogenous group or a collection homogenous subgroups in a constant mix, and that total production changes in a linear fashion through appropriate increase or decrease of seemingly interchangeable labor unit. But productivity rates in many firms are known to change with additional manufacturing experience in employee skill. Learning curve is intended to subsume the effects of all these resources of productivity. This learning phenomenon is quantifiable in the form of a learning curve, or manufacturing progress function. The purpose d this study is to show how alternative assumptions regarding a firm's labor force may be utilize by integrating conventional CVP analysis with learning curve theory, Explicit consideration of the effect of learning should substantially enrich CVP analysis and improve its use as a tool for planning and control of industry.

• 한국실천공학교육학회논문지
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• 제4권1호
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• pp.165-172
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• 2012

실천공학 교육을 위하여 피교육자에 대한 많은 실습과정이 요구되고 이 과정에서 여러 종류의 실습장비가 활용될 수 있다. 다양한 실습장비에 대한 다양한 피교육자들의 장비활용에 관한 학습능력을 나타낼 수 있는 방법으로 학습곡선이론의 적용방안을 모색하였다. 학습곡선이론은 기본적으로 생산관리 분야에서 활용되었던 이론으로, 인간공학적 측면에서 인간의 수행능력에 기반한 이론이다. 본 연구에서는 디자인 분야에서 활용되고 있는 시선추적장비를 대상으로 피교육자의 학습과정에 대한 학습곡선이론의 적용방안을 연구하였다. 시선추적장비의 하드웨어 셋업과 주시영역 기록의 두가지 실습과제를 교육한 후, 반복수행에 따른 과제수행시간을 측정하여 학습곡선모델을 적용하였다. 예측된 수행시간과 실제 수행시간과의 비교분석을 통하여 학습곡선모델의 적용가능성을 분석하였다. 그 결과 학습곡선모델은 실습장비를 활용한 실습교육에서 피교육자의 학습과정을 적합하게 묘사하는 것으로 나타났다.

• Journal of Gastric Cancer
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• 제18권2호
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• pp.182-188
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• 2018

Purpose: Despite the fact that there are several reports of single-port laparoscopic distal gastrectomy (SPDG), no analysis of its learning curve has been described in the literature. The aim of this study was to investigate the favorable factors for SPDG and to analyze the learning curve of SPDG. Materials and Methods: A total of 125 cases of SPDG performed from November 2011 to December 2015 were enrolled. All operations were performed by 2 surgeons (surgeon A and surgeon B). The moving average method was used for defining the learning curve. All cases were divided into 10 cases in a sequence, and the mean operative time and estimated blood loss data were extracted from each group. Results: Surgeon A performed 68 cases (female-to-male sex ratio, 91.1%:8.82%), and surgeon B performed 57 cases (female-to-male sex ratio, 61.4%:38.5%). The operative time of surgeon B significantly decreased after 30 cases ($157.8{\pm}38.4$ minutes vs. $118.1{\pm}34.5$ minutes, P=0.003); that of surgeon A did not significantly decrease before and after around 30 cases ($160.8{\pm}51.6$ minutes vs. $173.3{\pm}35.2$ minutes, P=0.6). The subgroup analysis showed that the operative time significantly decreased in the patients with body mass index (BMI) of <$25kg/m^2$ (<$25kg/m^2$:${\geq}25kg/m^2$, $159.3{\pm}41.7$ minutes: $194.25{\pm}81.1$ minutes; P=0.001). Conclusions: Although there was no significant decrease in the operative time for surgeon A, surgeon B reached the learning curve upon conducting 30 cases of SPDG. BMI of <$25kg/m^2$ was found to be a favorable factor for SPDG.

• 한국수자원학회논문집
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• 제54권spc1호
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• pp.1183-1193
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• 2021

Low flow는 하천수의 공급관리 및 계획, 관개용수 등 다양한 분야에 영향을 미친다. 이러한 유황곡선을 산정하기 위해서는 30년 이상의 충분한 기간의 유량자료의 확보가 필수적이다. 하지만 국가하천 단위 이하의 하천의 경우 장기간의 유량자료가 없거나 중간에 일정기간 동안 결측된 관측소가 있어 하천별 유황 곡선을 산정하기에 한계가 있다. 이에 과거에는 미계측 유역의 유황을 예측하기 위해 다중회귀분석(Multiple Regression Analysis), ARIMA 모형 등 통계학적 기반의 기법들을 사용하였지만, 최근에는 머신러닝, 딥러닝 모형의 수요가 증가하고 있다. 이에 본 연구에서는 최신 패러다임에 맞는 머신러닝 기법인 DNN기법을 제시한다. DNN기법은 ANN기법의 단점인 학습과정에서 최적 매개변수 값을 찾기 어렵고, 학습시간이 느린 단점을 보완한 방법이다. 따라서 본연구에서는 DNN 모형을 이용하여 미계측 유역에 적용 가능한 유황곡선을 산정하고자 한다. 먼저, 유황곡선에 영향을 미치는 인자들을 수집하고 인자들 간의 다중공선성 분석을 통해 통계적으로 유의한 변수를 선정하여, 머신러닝 모형에 입력자료를 구축하였다. 통계적 검증을 통해 머신러닝 기법의 효용성을 검토하였다.

• Communications for Statistical Applications and Methods
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• 제19권3호
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• pp.433-450
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• 2012

연구자가 같은 작업을 반복적으로 수행할 때, 작업 효율성은 연구에 관련된 지식, 경험, 기술이 축적되면서 향상된다. 결과를 얻기 위해 연구에 투자하는 시간은 같은 작업을 반복함으로써 줄일 수 있다. 이러한 현상을 학습곡선 효과(learning curve effect)라고 일컫는다. 학습곡선(learning curves)은 학습의 변화를 시각적으로 나타낸 것으로 이전의 학습곡선 연구에서는 시간을 일정한 구간으로 나누어 구간별 작업에 대한 숙련도의 평균 차이 여부를 확인하였다. 이러한 방법은 구간을 어떻게 나눌 것인가 하는 기준이 존재하지 않으며, 더욱이 이항 반응 자료로 모형을 적합하기 어려운 문제점을 가지고 있다. 본 연구에서는 이산형 확률변수 중 이항 반응 자료(베르누이자료)에 대한 학습곡선의 통계적 모형에 초점을 맞추고자 한다. 누적확률분포의 특성을 이용하여 모수를 추정하기 위해서 뉴튼-랩슨 방법(Newton-Raphson method)을 사용하였고, 이 연구에서 제안한 모형의 점근적 분포를 구하였다.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1992년도 추계학술대회논문집
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• pp.113-120
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• 1992

In this paper, a mathematical model of learning curve is proposed to study the finger's reaction time. The model is a logarithmic linear type which represents a learning curve appropriately, and parameters are estimated by the linear. The learning coefficient and percentage of a reaction time can be easily computed in the mathematical model. This quantitative approach provides an important information to be used for the working capability qualification for re-employment as well as for the adaptability estimation of aged workers.

• 대한인간공학회지
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• 제11권2호
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• pp.47-56
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• 1992

In this paper, a mathematical model of learning curve is proposed to study the fi- nger's reaction time. The model is a logarithmic linear type which represents a lear- ning curve appropriately, and parameters are estimated by the linear. The learning coefficient and percentage of a reaction time can easily computed in the mathematical model. This quantitative approach provieds an important information to be used fot the working capqbility qualification of re-employment as well as the adaptability estimation of aged workers.

• Journal of Gastric Cancer
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• 제13권1호
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• pp.26-33
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• 2013

Purpose: The aims are to: (i) display the multidimensional learning curve of totally laparoscopic distal gastrectomy, and (ii) verify the feasibility of totally laparoscopic distal gastrectomy after learning curve completion by comparing it with laparoscopy-assisted distal gastrectomy. Materials and Methods: From January 2005 to June 2012, 247 patients who underwent laparoscopy-assisted distal gastrectomy (n=136) and totally laparoscopic distal gastrectomy (n=111) for early gastric cancer were enrolled. Their clinicopathological characteristics and early surgical outcomes were analyzed. Analysis of the totally laparoscopic distal gastrectomy learning curve was conducted using the moving average method and the cumulative sum method on 180 patients who underwent totally laparoscopic distal gastrectomy. Results: Our study indicated that experience with 40 and 20 totally laparoscopic distal gastrectomy cases, is required in order to achieve optimum proficiency by two surgeons. There were no remarkable differences in the clinicopathological characteristics between laparoscopy-assisted distal gastrectomy and totally laparoscopic distal gastrectomy groups. The two groups were comparable in terms of open conversion, combined resection, morbidities, reoperation rate, hospital stay and time to first flatus (P>0.05). However, totally laparoscopic distal gastrectomy had a significantly shorter mean operation time than laparoscopy-assisted distal gastrectomy (P<0.01). We also found that intra-abdominal abscess and overall complication rates were significantly higher before the learning curve than after the learning curve (P<0.05). Conclusions: Experience with 20~40 cases of totally laparoscopic distal gastrectomy is required to complete the learning curve. The use of totally laparoscopic distal gastrectomy after learning curve completion is a feasible and timesaving method compared to laparoscopy-assisted distal gastrectomy.

• Journal of Gastric Cancer
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• 제15권3호
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• pp.151-158
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• 2015

Purpose: Obesity is associated with morbidity following gastric cancer surgery, but whether obesity influences morbidity after laparoscopic gastrectomy (LG) remains controversial. The present study evaluated whether body mass index (BMI) and visceral fat area (VFA) predict postoperative complications. Materials and Methods: A total of 217 consecutive patients who had undergone LG for gastric cancer between May 2003 and December 2005 were included in the present study. We divided the patients into two groups ('before learning curve' and 'after learning curve') based on the learning curve effect of the surgeon. Each of these groups was sub-classified according to BMI (<$25kg/m^2$ and ${\geq}25kg/m^2$) and VFA (<$100cm^2$ and ${\geq}100cm^2$). Surgical outcomes, including operative time, quantity of blood loss, and postoperative complications, were compared between BMI and VFA subgroups. Results: The mean operative time, length of hospital stay, and complication rate were significantly higher in the before learning curve group than in the after learning curve group. In the subgroup analysis, complication rate and length of hospital stay did not differ according to BMI or VFA; however, for the before learning curve group, mean operative time and blood loss were significantly higher in the high VFA subgroup than in the low VFA subgroup (P=0.047 and P=0.028, respectively). Conclusions: VFA may be a better predictive marker than BMI for selecting candidates for LG, which may help to get a better surgical outcome for inexperienced surgeons.