• The Korean Journal of Applied Statistics
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• v.22 no.4
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• pp.723-733
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• 2009

The crucial problems of K-means clustering are deciding the number of clusters and initial centroids of clusters. Hence, the steps of K-means clustering are generally consisted of two-stage clustering procedure. The first stage is to run hierarchical clusters to obtain the number of clusters and cluster centroids and second stage is to run nonhierarchical K-means clustering using the results of first stage. Here we provide automated K-means clustering procedure to be useful to obtain initial centroids of clusters which can also be useful for large data sets, and provide software program implemented using R.

• Journal of Biosystems Engineering
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• v.27 no.5
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• pp.433-450
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• 2002

The daily food intake for dairy cows has to be effectively controlled to breed a sound group of cows as well as to enhance the productivity of the cows. But, feed stuffs are fed in the common bulk for a group of cows in most cases despite that the individual food intake has to be varied. To obtain the feed for each cow, both the nutrient requirements and the nutrient composition of fred have to be provided in advance, which are based on the status of cows such as weigh marginal weight amount of milk, fat concentration in milk, growth and milking stages, and rough feed ratio, etc. Then, the mixed ration fur diet would be computed by the nutrient requirements constraints. However, when TMR (Total Mixed Ration) is conventionally supplied for a group of cows, it is almost impossible to get an optimal feed mixed ration meeting the nutrient requirements of each individual cow since the constraints are usually conflicting and over-constrained although they are linear. Hence, addressed in this paper is a simulated annealing (SA) technique to find the food intake for dairy cows, considering the characteristics of individual or grouped cows. Appropriate parameters fur the successful working of SA are determined through preliminary experiments. The parameters include initial temperature, epoch length. cooling scheduling, and stopping criteria. In addition, a neighborhood solution generation method for the effective improvement of solutions is presented. Experimental results show that the final solution for the mixture of feed fits the rough feed ratio and some other nutrient requirements such as rough fiber, acid detergent fiber, and neutral detergent fiber, with 100 percent, while fulfilling net energy for lactating, metabolic energy, total digestible nutrients, crude protein, and undegraded intake protein within average five percent.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.816-822
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• 2003

In this paper, we propose an efficient iteration control method with low complexity for Turbo TCM(Turbo Trellis Coded Modulation) decoding which will be used fur power-limited environment. As the decoding approaches the performance limit of a given turbo code, any further iteration results in very little improvement. Therefore, it is important to devise an efficient criterion to stop the iteration process and prevent unnecessary computations and decoding delay. This paper presents an efficient algorithm for turbo TCM decoding that can greatly reduce the delay and iteration number. The proposed method use adaptive iteration number according to the criterion using the extrinsic information variance parameter in turbo TCM decoding process. The simulation results show that the proposed technique effectively can reduce the decoding delay and computation with very little performance degradation.

• Korean Medical Education Review
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• v.10 no.2
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• pp.25-44
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• 2008

Objectives: Through using of the strong research method like a Randomized Controlled Trial: RCT, we have to heighten quality of Medical Education study. I'd like to introduce "CONSORT", which stands for Consolidated Standards of Reporting Trials. Contents: Preventive Service Task Force(200l) in USA proposed Levels of evidence for enlarging evidence-based Practice: EBP. And the CONSORT was introduced, which encompasses various initiatives developed by the CONSORT Group to alleviate the problems arising from inadequate reporting of randomized controlled trials (RCTs). the CONSORT has 13 guides like these: 1. How participants were allocated to interventions 2. Scientific background and explanation of rationale 3. Eligibility criteria for participants. The settings and locations where the data were collected. 4. Precise details of the interventions intended for each group and how and when they were actually administered 5. Specific objectives and hypotheses 6. Clearly defined primary and secondary outcome measures, When applicable. any methods to enhance the quality of measurements (e.g., multiple observations, training of assessors) 7. How sample size was determined. When applicable, explanation of any interim analyses and stopping rules 8. Method used to generate the random allocation sequence, Details of any restriction [of randomization] 9. Method used to implement the random allocation sequence 10. Who generated the allocation sequence, who enrolled participants. and who assigned participants to their groups 11. Whether or not participants, those administering the interventions, and those assessing the outcomes were blinded to group assignment. If done, how the success of blinding was evaluated 12. Statistical methods used to compare groups for primary outcome(s), Methods for additional analyses, such as subgroup analyses and adjusted analyses 13. Flow of participants through each stage (a diagram is strongly recommended) Specifically, for each group report the numbers of participants randomly assigned. receiving intended treatment, completing the study protocol. and analyzed for the primary outcome. Results and Conclusion: Randomized Controlled Trial: RCT guided of CONSORT will contribute to do stronger evidence-based medical studies.

• Journal of Audiology & Otology
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• v.25 no.4
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• pp.199-208
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• 2021

Background and Objectives: No known studies have investigated the influence of stimulus polarity on the Auditory Brainstem Response (ABR) elicited from level-specific (LS) chirp. This study is important as it provides a better understanding of the stimulus polarity selection for ABR elicited from LS chirp stimulus. We explored the influence of stimulus polarity on the ABR from LS chirp compared to the ABR from click at 80 dBnHL in normal-hearing adults. Subjects and Methods: Nineteen adults with normal hearing participated. The ABRs were acquired using click and LS chirp stimuli using three stimulus polarities (rarefaction, condensation, and alternating) at 80 dBnHL. The ABRs were tested only on the right ear at a stimulus rate of 33.33 Hz. The ABR test was stopped when the recording reached the residual noise level of 0.04 μV. The ABRs amplitudes, absolute latencies, inter-peak latencies (IPLs), and the recorded number of averages were statistically compared among ABRs at different stimulus polarities and stimuli combinations. Results: Rarefaction polarity had the largest ABR amplitudes and SNRs compared with other stimulus polarities in both stimuli. There were marginal differences in the absolute latencies and IPLs among stimulus polarities. No significant difference in the number of averages required to reach the stopping criteria was found. Conclusions: Stimulus polarities have a significant influence on the ABR to LS chirp. Rarefaction polarity is recommended for clinical use because of its larger ABR peak I, III, and V amplitudes than those of the other stimulus polarities.

• Korean Journal of Audiology
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• v.25 no.4
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• pp.199-208
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• 2021

Background and Objectives: No known studies have investigated the influence of stimulus polarity on the Auditory Brainstem Response (ABR) elicited from level-specific (LS) chirp. This study is important as it provides a better understanding of the stimulus polarity selection for ABR elicited from LS chirp stimulus. We explored the influence of stimulus polarity on the ABR from LS chirp compared to the ABR from click at 80 dBnHL in normal-hearing adults. Subjects and Methods: Nineteen adults with normal hearing participated. The ABRs were acquired using click and LS chirp stimuli using three stimulus polarities (rarefaction, condensation, and alternating) at 80 dBnHL. The ABRs were tested only on the right ear at a stimulus rate of 33.33 Hz. The ABR test was stopped when the recording reached the residual noise level of 0.04 μV. The ABRs amplitudes, absolute latencies, inter-peak latencies (IPLs), and the recorded number of averages were statistically compared among ABRs at different stimulus polarities and stimuli combinations. Results: Rarefaction polarity had the largest ABR amplitudes and SNRs compared with other stimulus polarities in both stimuli. There were marginal differences in the absolute latencies and IPLs among stimulus polarities. No significant difference in the number of averages required to reach the stopping criteria was found. Conclusions: Stimulus polarities have a significant influence on the ABR to LS chirp. Rarefaction polarity is recommended for clinical use because of its larger ABR peak I, III, and V amplitudes than those of the other stimulus polarities.

• Proceedings of the KOR-KST Conference
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• 1995.02a
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• pp.3-32
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• 1995

The Highway Capacity Manual specifies procedures for evaluating intersection performance in terms of delay per vehicle. What is lacking in the current methodology is a comparable quantitative procedure for ass~ssing the safety-based level of service provided to motorists. The objective of the research described herein was to develop a computational procedure for evaluating the safety-based level of service of signalized intersections based on the relative hazard of alternative intersection designs and signal timing plans. Conflict opportunity models were developed for those crossing, diverging, and stopping maneuvers which are associated with left-turn and rear-end accidents. Safety¬based level-of-service criteria were then developed based on the distribution of conflict opportunities computed from the developed models. A case study evaluation of the level of service analysis methodology revealed that the developed safety-based criteria were not as sensitive to changes in prevailing traffic, roadway, and signal timing conditions as the traditional delay-based measure. However, the methodology did permit a quantitative assessment of the trade-off between delay reduction and safety improvement. The Highway Capacity Manual (HCM) specifies procedures for evaluating intersection performance in terms of a wide variety of prevailing conditions such as traffic composition, intersection geometry, traffic volumes, and signal timing (1). At the present time, however, performance is only measured in terms of delay per vehicle. This is a parameter which is widely accepted as a meaningful and useful indicator of the efficiency with which an intersection is serving traffic needs. What is lacking in the current methodology is a comparable quantitative procedure for assessing the safety-based level of service provided to motorists. For example, it is well¬known that the change from permissive to protected left-turn phasing can reduce left-turn accident frequency. However, the HCM only permits a quantitative assessment of the impact of this alternative phasing arrangement on vehicle delay. It is left to the engineer or planner to subjectively judge the level of safety benefits, and to evaluate the trade-off between the efficiency and safety consequences of the alternative phasing plans. Numerous examples of other geometric design and signal timing improvements could also be given. At present, the principal methods available to the practitioner for evaluating the relative safety at signalized intersections are: a) the application of engineering judgement, b) accident analyses, and c) traffic conflicts analysis. Reliance on engineering judgement has obvious limitations, especially when placed in the context of the elaborate HCM procedures for calculating delay. Accident analyses generally require some type of before-after comparison, either for the case study intersection or for a large set of similar intersections. In e.ither situation, there are problems associated with compensating for regression-to-the-mean phenomena (2), as well as obtaining an adequate sample size. Research has also pointed to potential bias caused by the way in which exposure to accidents is measured (3, 4). Because of the problems associated with traditional accident analyses, some have promoted the use of tqe traffic conflicts technique (5). However, this procedure also has shortcomings in that it.requires extensive field data collection and trained observers to identify the different types of conflicts occurring in the field. The objective of the research described herein was to develop a computational procedure for evaluating the safety-based level of service of signalized intersections that would be compatible and consistent with that presently found in the HCM for evaluating efficiency-based level of service as measured by delay per vehicle (6). The intent was not to develop a new set of accident prediction models, but to design a methodology to quantitatively predict the relative hazard of alternative intersection designs and signal timing plans.

• Journal of Korean Society of Transportation
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• v.23 no.4 s.82
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• pp.7-16
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• 2005

Rejected Takeoff Accidents are not common. but if occurred, it leads to big disaster From the year of 1959, when Jet Transport service opened, to the year of 2000, Rejected Takeoff accidents/incidents occurred total of 94 cases. All cases led to overrun, and major cause is to initiate stopping maneuvers over $V_1$, takeoff decision speed, according to National Transport Safety Board of America. Similar results are represented in Aviation Safety Reporting System of National Aeronautics and Space Administration. So I believe that it is worth studying if Airplane Flight Manual, which is the reference Performance criteria, is appropriate to operations of line pilots. The definition of $V_1$ has been revised a couple of times and Rejected Takeoff Certification Standards for Transport Airplanes was changed in 1998. It shows that up to now there are some portions unreasonable. This study focused on gathering the pilot's tendency for current Rejected Takeoff Procedures of K airlines and analyze the factors they concern. I chose B777 airplane and actually measured the recognition and reaction time of the rejected takeoff transitions through Simulators. And compared the results with the data of flight test and Airplane Flight Manual.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.97-110
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• 2003

The sight distance at unsignalized intersections is the one of the fundamental geometric design elements, and can ensure safety and efficient operations. Despite its importance, little research attention has been directed in Korea compared to developed countries such as European countries, the United States, and Japan. AASHTO ISD policies have been applied to the intersection design in Korea without any revise, which can produce unrealistic and unadoptable design values. Those values are emerged from several reasons because the AASHTO ISD has been calibrated based on the local data. Therefore the ISD hardly takes into account the local characteristics of Korea such as driving behavior. vehicular movement and roadway conditions. The objective of this study is to calculate the appropriate ISD values for unsignalized intersections in the urban area in Korea. In this study, we employed the ISD model of AASHTO(2001), which is based on gap acceptance theory and can account for and take the driving and roadway conditions in Korea into consideration. The approach can also consider the complex driving maneuvers at the intersections in a proper and simple manner. The results in this study show that the ISD design criteria currently used in Korea are more conservative(safer) than those of the USA. In other words, the ISD using field data collected in this study has generally smaller values than those in USA.

• Journal of the Ergonomics Society of Korea
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• v.34 no.1
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• pp.45-62
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• 2015

Objective: The purpose of this study is to investigate the effect of personality type on human performance tool compliance in nuclear power plants (NPPs) and to propose general recommendations for an enhancement of its practical utilization. Background: Various guidelines, regulating criteria, and recommendations have been developed to prevent human errors in NPPs. Despite these efforts, the accidents sometimes caused by human errors have steadily occurred, and therefore, various human performance tools have been adopted as countermeasures against human errors. The major and inevitable contributing factors among the many hazards to human errors might be the trait and personality, which are considered to be the inner world of humans. Thus, we try to investigate the utilization of human performance tools by considering the different types of operating crew personalities, and we suggested more practical recommendations to prevent human errors according to the personality. Method: We developed the Questionnaire using the Big 6 (HEXACO) models, which are human performance tools for workers in NPPs, and individual (condition) variables to investigate the effect of personality types on human performance tools. We slightly modified them to help the survey respondents understand them better. A survey was conducted for ordinary people over the age of 20. SPSS 22.0 was used to perform a correlation analysis and a hierarchical regression analysis to find the relationship between personality types and human performance tools. Results: The utilization of human performance tools shows significant differences statistically by personality. The correlation result reveals that the types of Honesty (H), Extraversion (X), Conscientiousness (C), and Openness to experience (O) show a higher utilization of human performance tools. In hierarchical regression results, human performance tools of task preview, questioning attitude, stopping when unsure, self-checking, effective communication, and place-keeping show a higher utilization with personality types. However, the Agreeableness (A) type did not show significant differences statistically with human performance tools. Conclusion: We tried to investigate the utilization of human performance tools by considering the different types of human personality and provide more practical recommendations to prevent human errors according to the personality. These results will be able to prevent human errors owing to the characteristics (advantages and disadvantages) of personality types. Application: This information can be utilized as guidelines for proactive recommendations according to the workers' personalities for more practical human performance tools to prevent human errors in an NPP.