• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.168-174
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• 2017

In this work, a piezostack single-stage valve (PSSV) system is proposed and its control performance is experimentally evaluated at high temperature up to $150^{\circ}C$. In order to achieve this goal, a PSSV system is designed and operating principle and mechanical dimensions are discussed. A displacement amplifier and an adjust bolt are used to generate target displacement and to compensate thermal expansion. Then, an experimental apparatus is constructed to evaluate control performance of the PSSV system. The experimental apparatus consists of a heat chamber, a hydraulic circuit, a pneumatic circuit, pneumatic-hydraulic cylinders, thermal insulator, electronic devices, sensors, data acquisition (DAQ) board and a voltage amplifier. The flow rate and displacement control performance of the valve system are evaluated via experiment. The experimental results are evaluated and discussed at different temperatures and frequencies showing the controlled flow rate and spool displacement.

• Phonetics and Speech Sciences
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• v.11 no.4
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• pp.81-87
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• 2019

The purpose of the current study is to investigate the realization of speech rhythm in English as spoken by Korean learners of English. The study particularly aims to examine the rhythm metrics of English read speech by learners who speak Busan or the South Kyungsang dialect of Korean. Twenty-four learners whose L1 is Busan Korean and eight native speakers of English read a passage wherein five sentences were segmented and labeled as vocalic and intervocalic intervals. Various rhythm metrics such as %V, Varcos, and Pairwise Variability Indexes (PVIs) were calculated. The results show that Korean learners read English sentences with significantly more vocalic and consonantal intervals at a slower speech rate than native English speakers. The analyses of rhythm metrics revealed that when the speech rate was not normalized, Korean learners' English showed more variability in the length of consonantal and vocalic intervals. However, speech-rate-normalized rhythm metrics for vocalic intervals indicated that Korean learners transferred their L1 rhythmic structures (a syllable-timed language) into their L2 speech (a stress-timed language). Overall, the results suggest that Korean learners' English reflects the rhythmic characteristics of their L1. The effect of the learners' L1 dialect on the realization of L2 speech rhythm is also speculated.

• Journal of Ocean Engineering and Technology
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• v.31 no.1
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• pp.60-68
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• 2017

In this study, we analyzed the real time video image obtained from the video monitoring system to grasp the shoreline, beach width, and area change of Haeundae beach. The video monitoring techniques enabled continuous monitoring for a long period at a much lower cost than general survey methods. It was possible to grasp quantitative beach variation characteristics of Haeundae beach through image acquisition, rectification, and image processing of video images. According to the monitoring results, the erosion rate of Haeundae beach in spring and summer was -19.8% in 2014 and -6.7% in 2015. The erosion rate in 2016 was -6.4%, which showed that the erosion rate in spring and summer continued to decrease. In particular, the influence of the erosion at the time of typhoon CHABA was revealed to be smaller than in the past. It can be concluded that these variations were due to beach width expansion by beach nourishment and the installation of submerged breakwaters.

• 한국지구물리탐사학회:학술대회논문집
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• 2010.10a
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• pp.43-45
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• 2010

Acquisition of thermoremanent magnetization follows a Boltzman statistics, as such long reaction time in a slowly cooled environment allows more chance to align individual magnetic particles parallel to the external magnetic field. Hence it has been proposed that the slowly cooled rocks often acquire stronger magnetization than the rapidly cooled ones. Such a proposition has been experimentally validated to be true for the fine-grained magnetite- or titanomagnetite bearing basaltic rocks collected from the mid-ocean ridges. However, the effect of cooling-rate on the remanence intensity appears to be insignificant for nominal grain ranges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1433-1438
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• 2009

The purpose of this study is to investigate how the ignition spark timing conversion influences the engine performance of LPG/Gasoline Bi-Fuel engine. We propose the control system which can advance the ignition spark timing in LPG fuel mode more than used in gasoline fuel mode. In order to investigate the engine performance during combustion, engine performance are sampled by data acquisition system, for example cylinder pressure, pressure rise rate and heat release rate, while change of the rpm(1500, 2000) and the ignition timing advance($5^{\circ}$,$10^{\circ}$,$15^{\circ}$,$20^{\circ}$) As the result, between 1500rpm and 2000rpm, the cylinder pressure and pressure rise rate was increased when the spark ignition was advanced but pressure rise rate at $20^{\circ}$was smaller value. Also, the heat release rate at 1500rpm was increased but it was lower around $20^{\circ}$at 2000rpm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.7
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• pp.545-551
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• 2013

Timing recovery loop composed of the Timing Error Detector(TED), loop filter and resampler is widely used for the timing synchronization in MQASK receivers. Since TED is sensitive to the delay between the symbol period of the signal and sampling period, the output is averaged out when the symbol rate and sampling rate are quite different the recovery loop cannot work at all. This paper presents a sampling frequency discriminator (SRD), which detects the frequency offset of the sampling clock to the symbol clock of the MQASK data transmitted. Employing the SRD, the closed loop timing recovery scheme performs the frequency-aided timing acquisition and achieve the synchronization at extremely high sampling frequency offset, which can be used in variable symbol rate MQASK receivers.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.262-271
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• 2022

The purpose of this study is to investigate the status of admission and employment in fisheries high schools (FHS) and to consider ways to revitalize FHS through substantialization. The recruitment rate of new students in FHS decreased from 97.4% in 2016 to 83.2% in 2020. The aging training ship that FHS needs to improve most urgently is being jointly used by FHS across the country, and the construction of a joint training ship managed by the Korea Institute of Maritime and Fisheries Technology is being promoted. The average employment rate for FHS by year was 40.2-59.4%, and the fisheries-related employment rate was low at 31.0-38.9%. On the other hand, the acquisition rate of certificate of competence was 37.5-52.0%, and the rate of employment on board of those who obtained the certificate of competence was 42.9-59.8%. In order to secure new students and improve the recruitment rate, we operate experiential classrooms that reflect the characteristics of training ships and departments and conduct public relations activities using sns, publicity video ucc, YouTube, etc. It will be necessary to expand opportunities for fisheries-related vocational experience through active career exploration and elective courses in the FHS credit system. Finally, it is judged that fisheries related government agencies, industries and local governments need to improve their awareness of FHS and plan to support fisheries manpower nurturing in order to attempt the vitalization of FHS.

• Journal of Family Resource Management and Policy Review
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• v.13 no.3
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• pp.181-205
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• 2009

The purpose of this study is to investigate some Influencing factors related to the wealth perception and property increase of 519 women in Seoul. The research was conducted from the end of February 15 to the beginning of January 20, 2009. The figures obtained were analyzed by frequency, percentage, mean, x-test, t-test, F-test, chi-square, and Duncan's F-test with SPSS pc+ The major findings of who study are summarized as follows: l.There were significant differences between the wealth recognition (economic plan affirmative and negative perception of wealth) for women according to social and psychological variables; economic plans have a higher value for married women, older women, those who have followed a postgraduate university course, those with higher income and expenditure, higher life satisfaction, and high and middle satisfaction with their economic life. In particular, economic plans varied significantly according to expectation of wealth in old age, and future economic prospects in the middle group. 2. Increased wealth and economic according to social and psychological variables (marital status, age, education, income, expenditure, life satisfaction, satisfaction with economic life, expectation of wealth in old age, future economic prospects) were shown to be associated with the following methods of increasing property: use of savings banks (p<.001) showed a rate of deposit of 20%-40% (p<.001) saving and thrift was a practice (p<001) that was related to the cost of living; and education expenditure (p<.001) as a property preparation period was exhibited in women aged 25-30 (p<.001). 3. There were significant differences in the recognition of wealth according to strategies for increasing wealth. There were no significant differences between mean of property acquisition and point of expenditure or the property preparation period in the perception of wealth. The related variables in rate of deposits were under 20% according to economic plan and negative wealth perception. In contrast, in the middle and high group, the economic plan and negative wealth perception were 20%-40% in relation to the rate of deposits. Variables related to the action of saving and thrift and property acquisition were practiced in the low and middle group of affirmative wealth recognition and the high group of negative wealth perception. The high group for wealthrecognition and the low group for wealthnegation exhibited little savings, thrift, and property accumulation. Those variables which point an expenditure the cost of living were education expenditure in all groups of negative wealth perception. The women in the study practiced more soundness economic planning according to their increased wealth and economic strategy. This study suggests that women should have positive wealth perception in their lives.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.635-648
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• 2018

This study analyzed patent trends of seismic nodal systems and the technical characteristics of core patents of three major companies, including Fairfield, Sercel, and Wireless Seismic, to examine the focus of technology development of each company. From the analysis, the patent application growth rate of seismic nodal systems has steadily increased since early to mid-2000s and has recently shown a higher growth rate. Over the same period, the patent application growth rate of the three major companies examined was higher than that of the global trend, and patent infringement cases was also examined to evaluate market competition in this field. Analysis of the technical characteristics of the three companies' 33 core patents showed that they are generally focused on seismic signal detection. Sub-technologies included improved reliability of data acquisition, data transmission efficiency, and overall operating of the seismic nodal system. New entrants in field of technology development or manufacturing of seismic nodal systems where the market is growing must closely analyze the contents of major companies' products and patents to prevent possible patent disputes or duplicate research.

• Journal of Intelligence and Information Systems
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• v.9 no.1
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• pp.125-137
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• 2003

In eastern countries stamps have been used more commonly than signatures when approving contracts and documents. Unlike finger prints, stamp images do not share similar patterns to each other and the resolution of stamp images is determined by the input status such as pressure under which stamps are put. This paper discusses the development of a system for recognizing stamp images of Korean or Chinese characters. Recognition of stamp images consists of several steps: acquisition of stamp images from an input device, digitization, contrast stretching, noise removal, and matching. We tested the system on 50 stamp images (20 stamp images of Korean characters, 20 images of Chinese characters, and 10 similar images). There was little difference in discrimination rate between the stamp images of Korean character and those of Chinese characters. 46 stamps images out of 50 were successfully recognized, resulting in 92% discrimination rate. Orientation and pressure under which stamps are put played an important role in determining discrimination rate. Automated stamp image recognition can be made more practical and useful by extending the types of stamp images to ellipses and rectangles and by improving the discrimination rate.