• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.323-330
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• 2019

The 500 MW Korean standard coal-fired power plant is the largest standardized power plant in Korea and has played a pivotal role in domestic power generation for over 20 years. In addition to the aging degradation due to long term operation, the probability of failure of power generation facilities is increasing due to frequent startup and stop caused by the lower utilization rate due to air pollution problem caused by coal-fired power plants. Among them, steam piping plays an important role in transferring high-temperature & pressure steam produced in a boiler to turbine for power generation. In recent years, failure of steam piping of large coal-fired power plant has frequently occurred. Therefore, in this study, failure analysis of high pressure piping weld was conducted. We identify the damage caused by high stress due to abnormal supporting structure of the piping and suggest improved supporting structure to eliminate high stress through microstructure analysis and piping stress analysis to prevent the occurrence of the similar failure of other power plant in the case of repetitive damage to the main steam piping system of the 500 MW Korean standard coal-fired power plant.

• Journal of Korea Multimedia Society
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• v.14 no.7
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• pp.895-904
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• 2011

In welding machine that executes existing spot welding, wrong operation of system has often occurs because of their mechanical motion that can be caused by a number of supply like the welding object. In exposed working environment for various situations such as worker or related equipment moving into any place that we are unable to exactly distinguish between good and not condition of nut. Also, in case of defective welding of nut, it needs various evaluation and analysis through image processing because the problem that worker should be inspected every single manually. Therefore in this paper, if the object was not stabilization state correctly, we have purpose to algorithm implementation that it is to reduce the analysis time and exact recognition as to improve system of image processing. As this like, as image analysis for assessment whether it is good or not condition of nut, in his paper, implemented algorithms were suggested and list by group and that it showed the effectiveness through more than one experiment. As the result, recognition rate of normality and error according to the estimation time have been shown as 40%~94.6% and 60%~5.4% from classification 1 of group 1 to classification 11 of group 5, and that estimation time of minimum, maximum, and average have been shown as 1.7sec.~0.08sec., 3.6sec.~1.2sec., and 2.5sec.~0.1sec.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.767-776
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• 2009

The purpose of this paper is to design, implement and test the automatic marking system for programming languages using key-words and boolean operations to solve the processing problems of natural languages. There are accurate grammar systems and key-words in programming languages. Using these characteristics, We have designed, programmed, and tested automatic marking system for programming languages through key-words and boolean operations in this paper. We have categorized programming languages into 7 types as the type of answer and when a professor input any key-words, the system make him put conjunction with the special character. It can be logical expressions instantly so that the system easily operates. We asked 10 students who are majoring in computer engineering to take a test on the paper and web to show how well automatic marking system that we have programmed works. Then We requested 3 professors if the subject problems marked objectively. As a result, automatic marking system proved to be appropriate. We have proposed the way of using key-words and boolean operation for prohibiting huge natural language processing in marking of subjective question. It promotes efficiency rate of programming, objectivity and speed through the transferal to the web for marking since the system prohibits marker to include personal opinion on marking and gives feedback quickly

• Current Research on Agriculture and Life Sciences
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• v.27
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• pp.1-6
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• 2009

Persimmon occupied the second largest cultivation area next to apple among the fruits in Korea. Since 70 % of its cultivating field is located at slope, the efficiency of its harvesting operation is very low. Also, the traditional persimmon harvest apparatus does not seem to be efficient to use due to a structural problem. In this paper, the author has analyzed the physical properties of persimmon friut-stem system and compared detachment force with developed persimmon harvest apparatus and traditional persimmon harvest apparatus in order to solve the problems mentioned above. The results of the research are summarized as follows : 1. The weight of the persimmon is shown as 157 g on average, the lengths of stem's major axis and minor axis is shown as 4.6 mm and 3.7 mm on average, respectively, sectional area of stem is shown as $13.9mm^2$ on average and the stem length is shown as 13.6 mm on average. 2 In case of the traditional persimmon harvest apparatus, the detachment force needed when a persimmon was detached from its stem was shown as 86.3 N on average. 3. In case of the developed persimmon harvest apparatus, detachment force needed when a persimmon was detached from its stem was shown as 72.6 N on average.

• Journal of the Korean Institute of Navigation
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• v.21 no.2
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• pp.47-58
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• 1997

The purpose of this study is to find out the impacts of VTS on the marine safety and users' opinion on the VTS which have been being operated in the port of Pohang for the last 3 years and is to suggest a guideline to the successful operation of VTS in the future. This study is based upon the questionnaire survey and the respondents include 236 masters/mates of merchant vessels who have visited the port of Pohang and 6 pilots who have been working in the port. From the questionnaire results, this study notes the following conclusions related to the VTS operations. (1) A few of the respondents (mainly foreigners) do not understand the entering procedure of the port and the fundamental concept of VTS. Accordingly, the more active VTS services have to be provided for the mariners. (2) It was found that themost dangerous factors in tehvicinity of the port were the floating materials, fishing nets, andillegal fishing activities inthe fairway. Therefore, the proper surveillance, stricter enforcement of Acts and the instructive education for the fishermen are required to avoid the risks. (3) A majority of the respondents agreed the VTS has contributed to the safety of vessel traffic, and they pointed out ' the assiatances in reduced visibililty conditions' is the most important task of VTS. The amount of 75.6% of the respondents answered that they have experienced the assistance from VTS more than 1 time since the system was established in the port of Pohang . Also 44.2% of the respondents considered they were able to avoid marine casualties such as collision, ramming or agrounding with the VTS assistances. (4) 49.2% of the respondents preferred the passive information services , while, 38.8% of them preferred the positive control advices in the case of encountering any potential risks. VTS iperators have to consider seriously when they provide the positive control advices of ship's course and speed. (5) A majority of the respondents confirmed that the prot and its approaches is suitable for the VTS coverge . To extend the service areas of the VTS and to improve radar detecting ability, the use of radar transponders are seen as the ideal method. (6) A minority of the respondents pointed out 'the improper orders or recommendatinos caused by the poor decision making' firstly, ' the language problem(sea-speaking in English)' secondly, as the deficiency of personal qualification. It seems, therefore, theat the personal efforts of the operators and systematic training programmes for them are necessary to solve the problems.

• The KIPS Transactions:PartA
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• v.12A no.3 s.93
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• pp.205-214
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• 2005

Flash memory is at high speed used as storage of personal information utilities, ubiquitous computing environments, mobile phones, electronic goods, etc. This is because flash memory has the characteristics of low electronic power, non-volatile storage, high performance, physical stability, portability, and so on. However, differently from hard disks, it has a weak point that overwrites on already written block of flash memory is impossible to be done. In order to make an overwrite possible, an erase operation on the written block should be performed before the overwrite, which lowers the performance of flash memory highly. In order to solve this problem the flash memory controller maintains a system software module called the flash translation layer(FTL). Of many proposed FTL schemes, the log block buffer scheme is best known so far. This scheme uses a small number of log blocks of flash memory as a write buffer, which reduces the number of erase operations by overwrites, leading to good performance. However, this scheme shows a weakness of low page usability of log blocks. In this paper, we propose an enhanced log block buffer scheme, FAST(Full Associative Sector Translation), which improves the page usability of each log block by fully associating sectors to be written by overwrites to the entire log blocks. We also show that our FAST scheme outperforms the log block buffer scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1030-1038
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• 2013

The proposed Alamouti coded OFDM effectively cancels Inter Carrier Interference (ICI) due to frequency offset between distributed antennas. The conventional Alamouti coded OFDM schemes to mitigate ICI utilize N-point Inverse Fast Fourier Transform/Fast Fourier Transform (IFFT/FFT) operations for OFDM modulation and demodulation processes with total N subcarriers. However, the performance degrades because ICI is also repeated in N periods due to the property of N-point IFFT/FFT operation. In order to avoid this problem, null data are used at the subcarriers with large ICI and thus, data rate decreases. The proposed scheme employs 2N-point IFFT/FFT instead of N-point IFFT/FFT in order to increase sampling rate. By increasing sampling rate, the amount of interference significantly decreases because the period of ICI also increases. The proposed scheme increases the data rate and improves the performance by reducing amount of ICI and the number of null-data. Furthermore, the gain of the performance and data rate of the proposed scheme is significant with higher modulation such as 16-Quadarature Amplitude Modulation (QAM) or 64-QAM.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.256-265
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• 2013

With economic development and ever-changing technology, human has entered the era of "Product-as-a-Service". At the same time, the update of the product gradually accelerated. The demand of consumers for products are slowly changed, they pay more attention to convenience, comfort and reliable quality and safety of the product. That is the humanized design problem that often mentioned in the product design. This also put forward new requirements for the design and development of product modeling. So how to reflect the humanized ideas in the product design has also become common focus of attention of product designers, users and producers of a new era. The paper is based on the principles of ergonomics to investigate and improve the daily life utensil - flashlight. Firstly, make a sample survey of the flashlight in Beijing market and analyze the characteristics and problems of flashlight products. Secondly, explore the use of the flashlight and proposed Flashlight curved grip design to reduce the occurrence of wrist discomfort and damage to the body caused by poor posture of the operation of users. Finally, determine the range of the length and width of the body of the flashlight according to the length and width measurement data of the Chinese palm. Wishing that the improvements of flashlight products in ergonomics can improve use of feelings of these products and give a theoretical guidance for solving similar problems.

• Journal of Korean Society of Transportation
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• v.32 no.3
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• pp.239-247
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• 2014

In modern society, the transportation sector is having difficulties with mobility, safety, energy and environment issues so that solutions should be prepared progressively. Recently developed countries are paying greater attention to car-sharing systems as alternatives for relieving problems caused by increasing number of vehicles. Car-sharing systems are believed to keep the number of personal vehicles down and traffic congestion due to the fact that this system induces efficiency of vehicle operation. In this study, authors focused on solving the imbalance problem of car-sharing systems dynamically, to specifically improve one-way car sharing service. Therefore vehicle relocation algorithm was designed for maximizing profit of car sharing operators. For the application of the vehicle relocation algorithm among rental offices, we selected Haeundae-gu, Busan as the area of study. Rental offices have been designated to the zone centroid and we calculated the shortest path between rental offices by using TransCAD. In the study, we adapted MATLAB for the application of vehicle relocation algorithm. As the results, the total vehicle relocation time was estimated as 59.9 minutes. In addition, vehicle relocation algorithm was verified successfully by using Decision Tree method.

• Archives of Plastic Surgery
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• v.33 no.5
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• pp.581-586
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• 2006

Purpose: Pediatric burn still generates social problem leading to physical and mental sequelae for ages. We studied to help make a program for the prevention of pediatric burn. Methods: We analyzed retrospectically 2759 acute burn patients under the age of 15 years in recent 5years (January 2000 - December 2004). Results: 1553 males and 1226 females were investigated, with a male to female ratio of 1.25 : 1. The greatest number of burn patients were those with an age of 1 - 2 years(1435, 52%). Scalding burn was the most common cause of injury, which accounted for 1980 (71.8%) patients, followed by contact burns(286, 10.4%), flame burn(229, 8.3%), steam burn(141, 5.1%). Especially steam burn was the second cause of injury in the age under 1 year, while flame burn was the same in the age over 3 years. During recent 5 years, incidence of contact burn increased over twofold despite the others did not changed substantially. Variation of seasonal incidence is minimal and most of the patients(2545 cases, 92.2%) had burns of ${\leq}20%$ TBSA. The median hospital stay was 18.3 days, and the rate of operation was 35.4% with an high rate in electrical burn(70.6%), steam burn(68.8%), contact burn(65%). 27 patients died in this series, which yielded a mortality rate of 1%. Conclusion: We expect that these data will be used as a basis for prevention of pediatric burn.