• Asian-Australasian Journal of Animal Sciences
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• v.31 no.6
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• pp.820-826
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• 2018

Objective: The purpose of this retrospective study was to investigate the relationship between temperature-humidity index (THI), season, and conception rate (CR) of Holstein cows in central Taiwan. Methods: The mean performance and number of observations were statistically evaluated for various parameters, including age at first service, number of days open, gestation length, CR, and calving interval for different parities. Results: The results indicate that the mean age at first service was 493.2 days; the gestation length was similar across all cows of different parities, ranging from 275.1 to 280.7 days. The overall CR of all inseminations was significantly lower in multiparous cows ($47.26%{\pm}0.22%$) than in heifers ($57.14%{\pm}0.11%$) (p<0.05). At THI>72 and during the hot season (from June to November), CRs for multiparous cows were significantly reduced compared to that for heifers, while the ratio remained unchanged among heifers for all seasons. Conclusion: To achieve a high CR, lactating cows should be bred in winter and spring (from December to May) from the start of the seasonal breeding program, whereas the heifer should be allowed to breed in summer and fall under the subtropical climate in Taiwan.

• Journal of the Ergonomics Society of Korea
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• v.30 no.2
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• pp.339-347
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• 2011

Objective: The purpose of this study was to evaluate of various material of pillows by using biomechanical variables such as the cervical stability, head pressure distribution, and muscle activity. Method: Eight subjects participated in the experiment. Three different materials such as polyester sponge, memory foam and the buckwheat shell used for Korean traditional pillow were tested. Electro-goniometer, six channels of electromyography(EMG), ten channels of the head pressure sensors were used to measure the biomechanical responses. Surface electrodes were attached to the right/left semispinals capitis(RSC, LSC), the right/left sternocleidomastoid(RSM, LSM), the right/left upper trapezius(RUT, LUT). The cervical stability was evaluated by the angle deviated from the standing neck position. The head pressure distribution was evaluated by the pressure per unit area recorded on the sensors and the intensity of peak pressure. Electromyography(EMG) data were analyzed by using root mean square(RMS) and mean power frequency(MPF). Results: The buckwheat shell material showed a higher stability in the cervical spine then the other pillows during spine position. In terms of head pressure distribution, the memory form indicated the lowest pressure at supine position, buckwheat shell material indicated the lowest pressure during lying down to side, and polyester cushion recorded the highest pressure at all postures. Conclusion: The buckwheat shell material has a biomechanical advantage to maintain a healthy neck angle and reduce the pressure on the head, which means the buckwheat shell is a potential material for ergonomic pillow design. The pillow with memory form showed second best biomechanical performance in this study. Application: The shape of the buckwheat shell pillow and the characteristics of materials can be used to design the pillow preventing neck pain and cervical disk problems.

• Journal of the Ergonomics Society of Korea
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• v.31 no.5
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• pp.647-655
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• 2012

Objective: The purpose of this study was to confirm difference between angular foot movement time and existing foot Fitts' law predicting times, and to develop the angular foot Fitts' law in the foot tapping task. Background: Existing studies of foot Fitts' law focused on horizontal movement to predict the movement time. However, when driving a car, humans move their foot from the accelerator to the brake with a fixed heel. Therefore, we examined the experiment to measure angular foot movement time in reciprocal foot tapping task and compared to conventional foot Fitts' law predicting time. And, we developed the angular foot Fitts' law. Method: In this study, we compared the angular foot movement time in foot tapping task and the predicted time of four conventional linear foot Fitts' law models - Drury's foot Fitts' law, Drury's ballistic, Hoffmann's ballistic, Hoffmann's visually-controlled. 11 subjects participated in this experiment to get a movement time and three target degrees of 20, 40, and 60 were used. And, conventional models were calculated for the prediction time. To analyze the movement time, linear and arc distance between targets were used for variables of model. Finally, the angular foot Fitts' law was developed from experimental data. Results: The average movement times for each experiment were 412.2ms, 474.9ms, and 526.6ms for the 89mm, 172mm, and 253mm linear distance conditions. The results also showed significant differences in performance time between different angle level. However, all of conventional linear foot Fitts' laws ranged 135.6ms to 401.2ms. On the other hand, the angular foot Fitts' law predicted the angular movement time well. Conclusion: Conventional linear foot Fitts' laws were underestimated and have a limitation to predict the foot movement time in the real task related angular foot movement. Application: This study is useful when considering the human behavior of angular foot movement such as driving or foot input device.

• Journal of the Ergonomics Society of Korea
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• v.31 no.5
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• pp.629-636
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• 2012

Objective: The purpose of this study is to compare the characteristics of single and double finger gestures related on the web browser and to extract the appropriate finger gestures. Background: As electronic equipment emphasizes miniaturization for improving portability various interfaces are being developed as input devices. Electronic devices are made smaller, the gesture recognition technology using the touch-based interface is favored for easy editing. In addition, user focus primarily on the simplicity of intuitive interfaces which propels further research of gesture based interfaces. In particular, the fingers in these intuitive interfaces are simple and fast which are users friendly. Recently, the single and double finger gestures are becoming more popular so more applications for these gestures are being developed. However, systems and software that employ such finger gesture lack consistency in addition to having unclear standard and guideline development. Method: In order to learn the application of these gestures, we performed the sketch map method which happens to be a method for memory elicitation. In addition, we used the MIMA(Meaning in Mediated Action) method to evaluate gesture interface. Results: This study created appropriate gestures for intuitive judgment. We conducted a usability test which consisted of single and double finger gestures. The results showed that double finger gestures had less performance time faster than single finger gestures. Single finger gestures are a wide satisfaction difference between similar type and difference type. That is, single finger gestures can judge intuitively in a similar type but it is difficult to associate functions in difference type. Conclusion: This study was found that double finger gesture was effective to associate functions for web navigations. Especially, this double finger gesture could be effective on associating complex forms such as curve shaped gestures. Application: This study aimed to facilitate the design products which utilized finger and hand gestures.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.379-388
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• 2012

Objective: This study developed a new shower carrier prototype to reduce caregivers' muscle burden and to increase use convenience by reflecting the needs of domestic long-term care institutions. Background: In the long-term care institutions, one of the ADL(Activities of Daily Life) factors is bathing/showering. Recently, bath/shower-assisting equipment is actively being introduced in care institutions to reduce the caregivers' care cost, but most of the domestic equipment was designed to imitate foreign products and rarely reflected the needs of care institutions. Method: Based on Korean elderly people's body information, the bed size(length: 1,900mm, width: 650mm) was set-up, and a variable headrest with a newly designed headform was developed to provide the comfort for the elderly and convenience for caregivers. To reduce caregivers' muscle burden on transferring and showering activities, a 3-step column lifting module equipped with dual actuators(lowest/highest levels from the ground: 600/1,100mm, Stroke: 500mm) was developed, and the wheelbase parameter(length: 1,250mm, width: 580mm) was defined securing the turn-over safety of the shower carrier. The drivability tests were performed for the prototype and foreign product, and the male and female subject's muscle activities were measured through the tests. Results: The structural stability of the shower carrier prototype was secured by finite element analysis, and the muscle activities of the subjects through the drivability tests largely decreased in the prototype, compared to the foreign product. Conclusion: In this study, a new shower carrier prototype was developed to possibly reduce caregivers' muscle burden and to increase use convenience based on the needs of long-term care institutions. It was expected that the drivability performance of the prototype could be relatively superior to that of the foreign product. Application: The results obtained from the study can be applied for the optimal development of a shower carrier including other equipment to effectively care for the elderly.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.485-498
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• 2017

Objective: This study aims to survey and compare three systemic accident investigation techniques of Accimap, STAMP and FRAM, based on the application studies of the Sewol ferry accident. Background: Traditional accident investigation methods such as domino models, FTA, etc. work well for losses caused by physical component failures or actions of human in relatively simple systems, but are unable to depict mechanisms generating errors and violations in the current complex socio-technical systems. For better understanding the structure and behavior of the socio-technical systems, systemic techniques have been developed and used. Method: This study was mainly based on survey of literatures through surfing webpages of ScienceDirect and Google, and ergonomics relevant journals. The key words of Sewol, Sewol ferry, Sewol ferry accident, etc. were used in the survey. Results: Three systemic accident investigation methods included similar actors in the Sewol ferry accident including government, Ministry of Ocean and Fisheries, Korean Coast Guard, Korean Register of Shipping, Korea Shipping Association, Chonghaejin Marine Company, crew members. The methods graphically represented each level's failures or performance variabilities of relevant functions and relationships between them. It was shown that the systemic methods consider the entire system, ranging from the environment in which the accident occurred, to the role of government in shaping the system of work. Each method has its own comparative pros and cons, but the Accimap has advantages in terms of time of analysis, data required, model complexity and degree of comprehensiveness. Conclusion: This study reviewed and compared three systemic accident investigation methods, which showed that there are systemic characteristics and pros and cons in the methods. Application: The results would be used as a guideline when selecting accident investigation methods.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.535-543
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• 2017

Objective: This study was designed to identify factors affecting pilots' +Gz tolerance recovery from +Gz induced exhaustion. Background: +Gz tolerance of pilots has been considered as a crucial factor to fly the modern high performance fighter aircrafts. However, the factors affecting pilots' G-tolerance recovery from +Gz induced exhaustion have not been examined in the acceleration research community. Method: A centrifuge profile consisting of a high +Gz run for pilot's exhaustion and a low +Gz run for pilot's recovery and another high +Gz runs for pilot's second exhaustion was designed. The subjects' +Gz tolerance recovery ratio was measured by ratio of second high +Gz run time to the first high +Gz run time. The subjects' +Gz tolerance recovery rate was measured by dividing the subjects' +Gz tolerance recovery ratio by the low +Gz run time. The subjects' G-tolerance recovery rate was analyzed with respect to the subjects' personal factors including subjects' anthropometric and physiologic characteristics, flight time, flying aircraft type and so on. Results: The subjects' previous three-month flight hours (r=-0.336, p=0.039), six-month flight hours (r=-0.403, p=0.012) and one-year flight hours (r=-0.329, p= 0.044) correlated with the subjects' G-tolerance recovery rate. Conclusion: The subjects' G-tolerance recovery rate is clearly related to the subjects' previous flight hours. However, the subjects' anthropometric and physiologic characteristics do not show any statistically significant correlation with the subjects' G-tolerance recovery rate. Application: This research provides a safety critical insight to aviation community by identifying the factors to affect the gravity-induced loss of consciousness (GLOC) of pilots.

• English Language & Literature Teaching
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• v.9 no.2
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• pp.35-70
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• 2003

This study investigates the acquisition of English prepositions of location and direction by Malaysian Chinese ESL learners. It was conducted with the objective of finding out which of the two types of prepositions was more problematic to the L1 Chinese learners. The study also sought to investigate the effect of age and proficiency levels in English on the acquisition of the English prepositions of location and direction by these learners. Additionally, the study sets out to determine the extent to which the L1 Chinese learners have acquired the English prepositions of location and direction. This study involved three groups of Chinese ESL learners: elementary, intermediate and advanced. They were selected based on their age and their performance on a standardized proficiency test. The instrument used to collect data was a preposition test comprising 85 items. These items on prepositions of location and direction were randomly arranged in the tasks. The test required subjects to respond to multiple choice questions, match given sentences with appropriate prepositions, fill in blanks with the appropriate prepositions, judge given sentences to see if they are grammatical or ungrammatical and correct the ungrammatical sentence by providing the appropriate prepositions. The results indicate that age and proficiency levels of the learners made a difference in the acquisition of English prepositions of location and direction. The older learners with higher proficiency levels seem to fare better than the younger and less proficient learners. The results suggest that the prepositions of location arc slightly more problematic than prepositions of directions to the L1 Chinese learners. Our data also suggest that certain prepositions of each type are more problematic than others.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1625-1628
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• 2003

Recently the VR technique has evolved into a mixed reality (MR) technique, in which a user can observe a real world in front of him/her as well as virtual objects displayed. This has been realized by the employment of a see-through type HMD (S-HMD). We have been developing a mixed reality space employing the MR technique. The objective of our study is to realize a virtual human that acts as a man-machine interface in the real space. It is important in the study to create a virtual human acting naturally in front of a user. In order to give natural motions to the virtual human, we employ a developed motion capture technique. We have already created various 3-D human motion models by the motion capture technique. In this paper, we present a technique for creating a virtual human using a human model provided by a computer graphics software, 3D Studio Max(C). The main difficulty of this issue is that 3D Studio Max(C) claims 28 feature points for describing a human motion, but the used motion capture system assumes less number of feature points. Therefore a technique is proposed in the paper for producing motion data of 28 feature points from the motion data of less number of feature points or from incomplete motion data. Performance of the proposed technique was examined by observing visually the demonstration of some motions of a created virtual human and overall natural motions were realized.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.6
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• pp.411-418
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• 2020

In this paper, approximation and optimization methods are proposed for the structural performance of the composite fan blade. Using these methods, we perform the optimal design of the stacking sequence to maximize stiffnesses without changing the mass and the geometric shape of the composite fan blade. In this study, the lamination parameters are introduced to reduce the design variables and space. From the characteristics of lamination parameters, we generate response surface model having a high fitness value. Considering the requirements of the optimal stacking sequence, the multi-objective optimization problem is formulated. We apply the two-step optimization method that combines gradient-based method and genetic algorithm for efficient search of an optimal solution. Finally, the finite element analysis results of the initial and the optimized model are compared to validate the approximation and optimization methods based on the lamination parameters.