• The Journal of the Acoustical Society of Korea
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• v.34 no.2
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• pp.117-129
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• 2015

A parametric array is a nonlinear phenomenon that generates a narrow beam of low-frequency sound using the nonlinearity of the medium. The low-frequency sound so generated has a low sound pressure compared with that of sound generated directly. Consequently, a transducer that can generate a primary wave with high directivity and level is required. This study designed, fabricated, and evaluated a multi-resonance transducer as a parametric array source. The designs of the unit transducers and array transducer were based on an analysis model. The design process was repeated to fabricate the optimum transducer. The fabricated transducer array can generate a 189 dB, 190 dB primary wave level at 6.3 m and a 134 dB difference frequency wave using the parametric array phenomenon. The difference frequency wave has a frequency of 15 kHz and high directivity with an $8^{\circ}$ half power beam width in a $12{\times}18{\times}10m$ water tank.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.322-330
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• 2020

This study investigates the far-field noise from three Falcon 9 vehicle launches from Vandenberg Air Force Base, CA, USA, as measured from the same location within the nearby community of Lompoc. The overall sound pressure levels for the three launches are shown to be similar, but some differences in the early launch period are thought to be weather-related. The peak directivity angle in overall level is approximately 65 deg, which is consistent with horizontally-fired, static rocket data. For the third launch, waveforms and spectra are analyzed for different events during the launch sequence. The measured spectral bandwidth decreases with time, but spectral levels remain above the ambient noise throughout the main-engine firing. Additionally, late-launch phenomena observed in the data appear to be correlated with main-engine cutoff and second-stage engine start.

• Journal of Gifted/Talented Education
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• v.22 no.2
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• pp.353-370
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• 2012

The observation and recommendation system was recently introduced for selecting gifted-students in science, and it has required to arrange the reliable and valid selection criteria that could identify the high potential competency of them. In this study, we explored the competencies that could help to discriminate gifted-students' inner properties, and also developed the dictionary based on them. The competencies were extracted from the proven previous competency dictionaries/models and examined by the structured survey and the focus group interview in order to ascertain the competencies of the science-gifted students. The results revealed that there were two competency clusters such as cognitive and affective domains. The cognitive cluster consisted of 6 competencies as follows: goal suggestion, planning, information collection and analysis, problem solving, higher-order thinking, and expertise and self-development competency. The affective cluster consisted of 3 competencies: confidence, achievement orientation, and curiosity competency. The dictionary categorized by the names, definitions, key elements, and behavioral indicators and their levels of the derived competencies was developed. Findings were expected to provide the implications on the selection criteria of the potential science-gifted students through the observation and recommendation system.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2003.11a
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• pp.369-392
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• 2003

최근 물류환경의 변화로 제품의 신속한 수송과 고객 지향적 물류서비스 제공의 극대화를 꾀하려는 기업들은 제3자 물류의 활용에 커다란 관심을 가지게 되었다. 기업이 제3자 물류업체 활용을 통한 성과를 높이기 위해서는 고객서비스의 향상, 물류관련 비용의 절감 및 물류활동에 대한 운영효율의 향상을 수행할 수 있는 물류업체를 선정하는 것이 중요하다 할 것이다. 본 연구에서는 제3자 물류업체 선정과 관련한 주요 선행연구의 종합적인 고찰을 통하여, 제3자 물류업체 선정에 대한 평가기준들을 도출하였다. 선정을 위한 기준으로 비용, 물류서비스, 업체평가, 정보시스템의 4가지 항목으로 나누었고, 이를 계층화하여 AHP기법을 통하여 분석하였다. 그 결과 상위기준의 상대적 중요도는 물류서비스가 0.425로 가장 높게 나타났고, 비용(0.232), 정보시스템(0.224), 업체평가(0.120) 순으로 나타났다. 비용의 항목에 포함되어 있는 하위기준의 중요도는 경제성이 0.710, 안정성이 0.290으로 나타났다. 물류서비스 항목에 포함되어 있는 하위기준의 중요도는 신뢰성이 0.780, 유연성이 0.220로 나타났다. 업체평가 항목에 포함되어 있는 하위기준의 중요도는 기업역량이 0.507, 관계지향성이 0.493로 나타났다. 정보시스템 항목에 포함되어있는 하위기준의 중요도는 정보인프라가 0.471, 정보활용도는 0.529로 나타났다. 분석에 있어 추가적으로 학계와 실무계 전문가 집단으로 나누어 그 중요도를 산출하였는데, 학계 전문가 집단과 실무계 전문가 집단 모두 상위기준에 있어 물류서비스가 가장 높게 나타났다. 주목할만한 점은 학계 전문가 집단의 경우 정보시스템이 비용보다 더 높게 나타난 반면에, 실무계 전문가 집단은 비용이 정보시스템 보다 더 높게 나타났다는 것이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1551-1562
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• 2000

In the using of FBG developed in home land, we designed and manufactured three types of FBG sound transducers the first in Korea. On FBG transducers manufactured we made an demonstrated on respective frequency response peculiarties in the water and analyzed the special characters. As the experimental result on frequency response peculiarities, we made t possible underwater acoustic detection on C type to maximum 18kHz, And for the purpose of realization on multi-point signal detection on wide scope in the water, in the using of WDM(Wavelength Division Multiplexing) method and passive band-pass filter system, established arrays system and succeeded in multi-point underwater acoustic signal detection to the frequency 1.3KHz out of the two B type FBG transducers. Additionally, it would be possible directivity detection for the objects of its source as the intensity of detection signal varies with the sound source's direction and angle. From now on we prepared a new moment on the practical used study on FBG hydrophone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.985-997
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• 1999

In this paper, the detection of 1 g and 10 g averaged SAR on human head caused by PCS handheld phones is analyzed and discussed. Conventional monopole antenna and planar structured PIFA are used in the computational model to apply to the antennas mounted on handheld phone. These antennas are designed to operate in the near of frequency 1.8 GHz, human head model is sampled to have cell size 1.5 mm and sloped to front direction by 30$^{\circ}$. It is found that, when monopole antenna is applied, 1 g averaged SAR is 1.4 W/kg, 10 g averaged SAR is 0.7 W/kg, when PIFA is applied, for each case, SARs are 1.143 W/kg, 0.4866 W/kg. While the radiation pattern of the monopole antenna is symmetrical, that of planar structured antenna is asymmetrical and SAR caused by PIFA is less than SAR by the monopole antenna. The radiation efficiency of PIFA is 62.6%, which is higher than that of monopole, 53%.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.949-958
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• 2018

A voice recognition control system is a system for controlling a peripheral device by recognizing a voice. Recently, a voice recognition control system have been applied not only to smart devices but also to various environments ranging from IoT(: Internet of Things), robots, and vehicles. In such a voice recognition control system, the recognition rate is lowered due to the ambient noise in addition to the voice of the user. In this paper, we propose a dual channel acoustic beamforming hardware architecture for MEMS(: Microelectromechanical Systems) microphones to eliminate ambient noise in addition to user's voice. And the proposed hardware architecture is designed as ASIC(: Application-Specific Integrated Circuit) using TowerJazz $0.18{\mu}m$ CMOS(: Complementary Metal-Oxide Semiconductor) technology. The designed dual channel acoustic beamforming ASIC has a die size of $48mm^2$, and the directivity index of the user's voice were measured to be 4.233㏈.

• The KIPS Transactions:PartD
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• v.9D no.4
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• pp.733-744
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• 2002

This paper propose a communication-based model of relationship marketing and study relationship development between e-business marketing and traditional marketing theory and then show the application of improved relationship marketing model in the e-business. Although e-business already has been an important area, there were so few studies on customer relationship management in e-business. Using the two aspects of communication process and effectiveness at which two precedent effect factors on the trust of customer relationship development and relationship commitment, this paper develop a communication-based model of internet marketing in th e-business.

• Journal of the Korean association of regional geographers
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• v.20 no.3
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• pp.269-281
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• 2014

Urban communities have been recently highlighted as an alternative idea in the field of urban regeneration, social economy and so on. Urban communities should not be understood as an ideal, but the way urban communities work in reality also should be analysed. This paper aims to find out what urban communities really mean and who are involved in urban communities. The paper explores the features and issues of unban communities by surveying residents in Ansim area, Dong-gu, Daegu city. The paper analyses the relation between participation and community features: residents' socio-economic features, residence features, social relationship with their neighbours and the sense of community. The survey outcome shows that middle income, higher educated residents living in apartment complex are relatively more involved in community activities. Moreover, those who have more relationship with their neighbours have participated in community activities more than those who do not have any. As a consequence, this paper carefully states that the urban community is middle class-oriented and such feature could cause other residents' limited opportunities to access information about their own community and lead to social exclusion. This paper suggests that urban community groups need 'soft solidarity' between social classes.

• The Journal of the Korea Contents Association
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• v.17 no.9
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• pp.650-660
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• 2017

This study is to suggest a new method of analyzing personality types of characters in narrative. First, we examined the history of the taxonomy of character types that existed in narrative theories so far. Until now, the classification of character types in narrative theory consisted largely of a formal classification based on roles in narrative, a content classification based on human internal qualities, and a complementary classification in which the two classification criteria are united. The problem with the existing character classification type is difficult to categorize it in spite of the usefulness of the content classification based on human internal qualities. On the other hand, the classification based on the role of the character in the narrative does not help as much as a practical analysis methodology because the classification is formal. In this study, we try to solve this problem by introducing Shalom Schwartz's human value type, and to make human character's value type and human role correlated with each other as a new character analysis methodology. Schwartz's study of value type is a very effective method to grasp the motivation of human behavior, and it seems to be very meaningful in analyzing the directivity of characters.