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택배 배송 작업의 공정분석을 통한 인간공학적 접근 방안
이세정,진상은,장성록 한국안전학회 2024 한국안전학회지 Vol.39 No.1
In response to the COVID-19 pandemic, the logistics industry in Korea has rapidly been expanding, with offline demand concentrating on online platforms owing to the development of digital infrastructure. This has increased the workload of courier drivers considerably, along with labor intensity. A delivery driver died recently from overwork due to the continuous increase in delivery volume, which raises social concerns. Delivery drivers work long hours, (over 12 hours) and are greatly affected by weather conditions, such as snow, rain, heat waves, and cold waves. In addition, they lack a fixed workplace; perform atypical work handling workpieces of various sizes, weights, and shapes; and spend a large amount of time driving as part of their work. This work involves a high level of tension and requires attention and concentration. Despite the frequency of industrial accidents in the courier industry, studies on safety and health to quantitatively analyze and systematize the work of courier workers are very scarce. Therefore, to define the work process necessary for investigating the harmful factors in delivery service and the work analysis, this study conducted interviews and on-site surveys to analyze the unit work of the delivery service by targeting delivery workers. In other words, a framework of unit work for work analysis was presented to enable research and analysis by considering the aforementioned characteristics of the courier industry. The process was broadly divided into work, transport, storage, delay, and inspection. Work was divided into loading, sorting, unloading, and door subcategories, and transportation was divided into vehicle, cart, and walking subcategories as well as 10 small processes. Moreover, 22 unit works were again drawn by conducting field surveys and interviews. The risk of unit work derived from this study was ergonomically evaluated, and the ergonomic analysis revealed that uploading and transportation were the most dangerous. The results of this study could be used as basic data for preventing industrial accidents among courier workers, whose work has increased with the logistics volume and the development of the logistics industry.
이세정,Lee, S. J. 대한기계학회 1994 대한기계학회논문집 Vol.18 No.9
A method to evaluate the position performance for a stochastically defined planar robot manipulator is presented. Performance is defined as the operational reliability based upon the positional errors of the manipulator tip. An analytical method is developed and applied to a two-link robot manipulator through forward kinematics. This study includes uncertainties in the link length, pin center location and radial clearance. By virtue of the effective link length model, only the nominal manipulator model and statistical information on the uncertainties are required. The results from the analytical method is compared to those from the Monte Carlo simulation.
이세정,정성범,박경진,Lee, Se-Jung,Jeong, Seong-Beom,Park, Gyung-Jin 대한기계학회 2013 대한기계학회논문집 Vol.37 No.5
강건최적설계의 개념은 다구찌 법에 근간을 두고 있다. 특히, 목적함수의 강건성 지수들은 설계변수나 파라미터의 변동에 둔감하고 보수적인 설계를 추구한다. 그 목적을 달성하기 위해 다양한 강건성 지수들이 소개되고 있다. 소개된 다양한 지수와 방법은 나름의 목적과 의미를 지니고 있다. 하지만, 다구찌 법에서 의미하는 강건설계의 의미를 목적함수의 강건성 지수로 반영하여 최적설계 문제로 확장하는 것에는 한계점이 발생할 수 있다. 본 논문의 목적은 기존 강건성 지수 연구들의 특징과 한계점을 파악하고 강건최적설계 연구의 고찰을 수행하는데 있다. 목적함수의 강건성 지수들의 특징을 확인하기 위해 결정론적 최적해와 강건해의 구분이 명확한 수학적 예제를 사용하여 평가를 수행하고 분석하였다. 더불어, 고찰을 토대로 강건최적설계에서의 강건성에 대한 새로운 관점과 상한함수를 사용한 목적함수의 강건성 지수를 제시하였다. The concept of robust optimization is based on Taguchi's method. Especially, robustness indices of objective function pursue an insensitive and conservative design when there are variations on design variables and parameters. To accomplish the purpose, various robustness indices on the objective function have been developed. However, it can be caused limitations to develop the robustness index, because there is difference between the Taguchi's method and robust optimization. In this paper, an investigation is performed to identify the characteristics and the drawbacks of the previous studies. To achieve the purpose, evaluations are conducted by using the examples which have both a deterministic optimum and a robust optimum. Moreover, a new viewpoint as well as a robustness index using a supremum value of the objective function is proposed based on the investigation.
PECVD방법으로 형성한 $W_{67}N_{33}$/GaAs구조의 열적 특성
이세정,홍종성,이창우,이종무,김용태,민석기,Lee, Se-Jeong,Hong, Jong-Seong,Lee, Chang-U,Lee, Jong-Mu,Kim, Yong-Tae,Min, Seok-Gi 한국재료학회 1993 한국재료학회지 Vol.3 No.5
Self-alignment gatc Schottky contact structure on Si- implanted GaAs was formed by plasma enhanced chemical vapor dcposirion. Tungsten nitride thin films (ahclut 1600$\AA$) \vcre dopositcd on GaAs at $350^{\circ}C$ in order to fahricarc GaAs 1Cs and ttwn rapidly annealed at $750^{\circ}C$ to $900^{\circ}C$. Thermal charac tcristics of PECVD)-$W_{67}N_{43}$/GaAs structure were investigated by X-ray diffraction, photolumintesccnce. and optical deep level transient specrroscopy. Results revealed that $W_{67}N_{33}$ gate was more thermally sta ble with GaAs substrate than W gate and Si atoms implanted In $W_{67}N_{33}$/GaAs structure became morr active than those In W/GaAs after annealing. I-V characteristics of $W_{67}N_{33}$/GaAs diod c exhibired a nearly ideal diode behavior. The termal stability of $W_{67}N_{33}$/GaAs diode was better than that of W/GaAs diode with the post annealing at temperatures from 800 to $900^{\circ}C$ for 20s without As overpressure.
이세정 대한기계학회 1994 대한기계학회논문집 Vol.18 No.2
A probabilistic model and analysis methods to determine the means and variances of the velocity and acceleration in stochastically-defined planar pin jointed kinematic chains are presented. The presented model considers the effect of tolerances on link length and radial clearance and uncertainty of pin location as a net effect on the link's effective length. The determination of the mean values and variances of the output variables requires the calculation of sensitivities of secondary variables with respect to the random variables. It is shown that this computation is straightforward and can be accomplished by a conventional kinematic analysis package with minor modification. Thus, the concepts of tolerance and clearance have been captured by the model and analysis. The only input data are the nominal linkage model and statistical information. The "effective link length" model is shown to be applicable to both analytical solution and Monte Carlo simulation. The results from both methods are compared. This paper Ksolves the higher-order kinematic problems for the probabilistic design analysis of stochastically-defined mechanisms.echanisms.