• Journal of Korean Society of Forest Science
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• 제85권2호
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• pp.316-324
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• 1996

This study was conducted by relative time study to identify the allowance time and basic work time, which is together composed of the total work time, in the wage composition and work process composition. This study was done for the case of a basic one person a group from thinning treatment for some conifer species such as Japanese red pine, Japanese larch, pitch pine and Korean pine. 1. In order to apply the Japanese allowance time of four species to the general conifer case, the maximum value of allowance time composition value among those of four species was selected. The results are as follows: delay time for person 1.8%, rest time 14.1%, delay time for machine 12.5% and wating time 0.4%. The some of ratios of adjustment allowance time is 28.8%. 2. Estimated wage basis time table, which can be used for wage table or process table, was prepared by adding up adjusted general allowance time and standard work time estimated by estimation equation for each species through the time study.

• Journal of the Ergonomics Society of Korea
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• 제35권6호
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• pp.595-609
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• 2016

Objective: The purpose of this study was to develop and validate the guidelines for Medic Work Table (MWT) based on the anthropometric data of medical technologists. Background: Users' anthropometric data such as sitting height, sitting elbow height, knee height, and so on are significant factors for designing comfortable and useful furniture. Thus, many guidelines for different types of desks and chairs based on the users' anthropometric data have been suggested to many researchers. However, few researches have been conducted to provide design guidelines for MWT for blood collecting task. Medical technologists often use their upper extremities to perform blood collecting task with high repetitions. These repeated motions could be a critical factor in the prevalence rate of Work-related Musculoskeletal Disorders (WMSDs). Therefore, a study on ergonomic design of MWT would be essential in preventing the WMSDs and improving the quality of the working environment of medical technologists. Method: This study suggested design guidelines for ergonomic MWT by focusing on the heights of the upper side and underside, depths of the inside and outside, and width of MWT through anthropometric studies and literature reviews. Afterwards, a new MWT was made using the suggested design guidelines for this study. Five healthy medical technologists participated to evaluate the original MWT and new MWT. All participants took part in the range of motion (ROM) test, electromyography (EMG) muscle activity test, and usability test to validate the suggested guidelines in this study. EMG signals of related muscles (Flexor Carpi Ulnaris, Extensor Carpi Ulnaris, Deltoid Anterior, and Biceps Branchii) were recorded through the surface electromyography system from both the original MWT and the new MWT. The ROM test of the shoulder and elbow flexion was also assessed using motion sensors. Results: The newly designed MWT showed decreased ROMs of the shoulder and elbow up to 22% and 18% compared to the original MWT. The muscle activities in the new MWT also showed a decrease of 13% in Anterior Deltoid, 6% in Biceps Brachii, 5% in Flexor Carpi Ulnaris, and 8% in Extensor Carpi Ulnaris muscle groups, compared to the original MWT. In the usability test, the satisfaction score of the new MWT was also 56.1% higher than that of the original MWT. Conclusion: This study suggested guidelines for designing MWT and validating the guidelines through qualitative and quantitative analyses. The results of motion analysis, muscle activity, and usability tests demonstrated that the newly designed MWT may lead to less physical stress, less awkward posture, and better physical user interface. Application: The recommended guidelines of the MWT would be helpful information for designing an ergonomic MWT that reduces physical loads and improves the performance of many medical technologists.

• Earthquakes and Structures
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• 제12권6호
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• pp.629-641
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• 2017

Foundation plays a significant role in safe and efficient turbo machinery operation. Turbo machineries generate harmonic load on the foundation due to their high speed rotating motion which causes vibration in the machinery, foundation and soil beneath the foundation. The problems caused by vibration get multiplied if the soil is poor. An improperly designed machine foundation increases the vibration and reduces machinery health leading to frequent maintenance. Hence it is very important to study the soil structure interaction and effect of machine vibration on the foundation during turbo machinery operation in the design stage itself. The present work studies the effect of harmonic load due to machine operation along with earthquake loading on the frame foundation for poor soil conditions. Various alternative foundations like rafts, barrette, batter pile and combinations of barrettes with batter pile are analyzed to study the improvements in the vibration patterns. Detailed computational analysis was carried out in SAP 2000 software; the numerical model was analyzed and compared with the shaking table experiment results. The numerical results are found to be closely matching with the experimental data which confirms the accuracy of the numerical model predictions. Both shake table and SAP 2000 results reveal that combination of barrette and batter piles with raft are best suitable for poor soil conditions because it reduces the displacement at top deck, bending moment and horizontal displacement of pile and thereby making the foundation more stable under seismic loading.

• Journal of the Institute of Electronics Engineers of Korea SC
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• 제49권4호
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• pp.78-89
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• 2012

The generated torque of a switched reluctance(SR) motor is highly nonlinear, which makes it difficult to determine the reference current commands for minimum torque ripples. In this paper, we present a computationally simple and efficient method to minimize torque ripples of SR motors based on iterative learning control. The reference current command of each phase minimizing torque ripples is identified in 2-dimensional look-up table form. Our learning control algorithm does not require the torque model, so our method is not affected by model errors and hence is very accurate. In order to justify our work, we present some computer simulation results.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제66권12호
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• pp.1899-1904
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• 2017

This paper presents a new one-time password approach generated based on $4{\times}4$ pattern schedule. It demonstrates generation of passkey from initial seed of random codes and mapping out in table pattern schedule which will produce a new form of OTP scheme in protecting information or data. The OTP-2FA has been recognized by many organizations as a landmark to authentication techniques. OTP is the solution to the shortcomings of the traditional user name/password authentication. With the application of OTP, some have benefited already while others have had second thoughts because of some considerations like cryptographic issue. This paper presents a new method of algorithmic approach based on table schedule (grid authentication). The generation of OTP will be based on the random parameters that will be mapped out in rows and columns allowing the user to form the XY values to get the appropriate values. The algorithm will capture the values and extract the predefined characters that produce the OTP codes. This scheme can work in any information verification system to enhance the security, trust and confidence of the user.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.1051-1054
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• 2005

On this study, we optimized minimizing the characteristic function for mixed result of the structural contact analysis and the buckling analysis according to the pin jig initial model's level change using mixed the table of orthogonal away and ANOM, Pin jig's weight is reduced up to 20 percent considering constraint conditions. Also we optimized reducing 20 percent weight of pin jig model using topology optimization.

• Geomechanics and Engineering
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• 제17권2호
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• pp.181-194
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• 2019

Due to the seepage of groundwater, the resisting force of slopes decreases and the sliding force increases, resulting in significantly reduced slope stability. The instability of most natural slopes is closely related to the influence of groundwater. Therefore, it is important to study slope stability under groundwater seepage conditions. Thus, using a simplified seepage model of groundwater combined with the analysis of stresses on the slip surface, the limit equilibrium (LE) analytical solutions for two- and three-dimensional slope stability under groundwater seepage are deduced in this work. Meanwhile, the general nonlinear Mohr-Coulomb (M-C) strength criterion is adopted to describe the shear failure of a slope. By comparing the results with the traditional LE methods on slope examples, the feasibility of the proposed method is verified. In contrast to traditional LE methods, the proposed method is more suitable for analyzing slope stability under complex conditions. In addition, to facilitate the optimization of drainage design in the slope, stability charts are drawn for slopes with different groundwater tables. Furthermore, the study concluded that: (1) when the hydraulic gradient of groundwater is small, the effect on slope stability is also small for a change in the groundwater table; and (2) compared with a slope without a groundwater table, a slope with a groundwater table has a larger failure range under groundwater seepage.

• Korean Journal of Agricultural Science
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• 제48권3호
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• pp.473-482
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• 2021

In this study, we attempted to estimate the degree of management of chestnut forestry households in Chungcheongnam-do and to provide information for establishing chestnut cultivation-related policies. The chestnut management standard diagnostic table consists of three major categories, namely, management base, management and sales capacity, and production technology levels, along with 19 subcategories. A survey of 309 chestnut forestry households was conducted from 2014 to 2019 in Gongju, Cheongyang, and Buyeo in Chungcheongnam-do. The average score for the 19 subcategories was 65.7 points, indicating that these areas have excellent management conditions. When the total score was higher, the output per hectare and the rate of top-grade products in the total output were also higher, indicating a significant correlation. These findings will be useful for providing consulting services to chestnut growers as they highlight the correlation between the higher scores of the indicators in the chestnut management standard diagnostic table and the management performance of the farmers. We found that the scores of the indicators for management and sale skill, such as management record and analysis, material purchase, and direct transaction with consumers, were relatively lower than those of the indicators for management base and production skill. It is assumed that the chestnut growers aging has led to negligence in recording details on incomes, expenditures, and work and lowered the willingness to make substantial profits. Therefore, it is essential to overcome these problems for profitable chestnut farming.

• Korean Journal of Agricultural Science
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• 제48권3호
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• pp.483-492
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• 2021

This study attempted to estimate the degree of management of oak mushroom farms in Chungcheongnam-do and to provide information to establish oak mushroom cultivation-related policies. The oak mushroom management standard diagnostic table consists of three major categories, growing condition, inoculation management, cultivation management and management administration, along with 20 subcategories. Thus, 209 households of oak mushroom farms were surveyed from 2015 to 2018 in Gongju, Cheongyang, Buyeo and Seochun in Chungcheongnam-do. The average score for the 20 subcategories was 71.5 points (representing a significant level), indicating that these areas have excellent management conditions. The analysis of the management performance indicators revealed a high number of indicators with scores of five or above. The total score was higher, and the amount per bed log and the rate of top-grade products in the total output were also higher, indicating a significant correlation. These findings will provide consulting services to oak mushroom growers as they highlight the correlation between the higher scores of indicators in the oak mushroom management standard diagnostic table and the management performance of farmers. We found that the scores of the indicators for management administration, such as management record and analysis and fund plan were relatively lower than those of other indicators. It is assumed that the owners aging has led to negligence in recording the details on incomes, expenditures, and work and lowered the willingness to make substantial profits. Therefore, it is essential to overcome these problems for profitable oak mushroom farming.

• Journal of the Korean Society for Precision Engineering
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• 제12권2호
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• pp.48-58
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• 1995

A micro positioning system using piezoelectric actuators have very wide application region such as ultra-precision machine tool, optical device, measurement systen. In order ro keep a high precision displacement resolution, they use a position sensor and feedback the error. From the practical point of view, a high-resolution displacement sensor system are very expensive and difficult to guarantee such sensitive sensors work properly in the hard opera- tion environment of industry. In this study, a micro-positioning grinding table which does not require position sensor but uses piezoelectric voltage feedback, has been developed. It is driven by hystersis-considering reference input voltage which calculated from computer and then uses actuator/sensor characteristics of piezoelectric materials. From the result of experiments we proved a fast and stable response of micro-positioning system and suggested efficient technique to control the piezoelectric actuator. And through grinding experiments, it is revealed that a characteristics of ground surfaces transient to plastic deformation as extremely small depth of grinding.