• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.97-104
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• 2008

This study was intended to evaluate the permeable performance through a change of reinforcing materials, curing condition, durability evaluation and permeability test, and to select the reinforcing material which could reduce the durability and water tightness from it, as the study for considering how the change of the outside's environment factors that the concrete structure actually contacted with impacted the concrete's durability especially the permeability by referring to such the background of the study. Accordingly, it was judged that evaluating the permeability by considering the severe environment condition where the concrete structure was placed in was more reasonable than measuring the existing permeability coefficient conducted in the sound state for the permeability evaluation of actually-used concrete structure. In this study, it also could be known that the specimen of hybrid fiber reinforced concrete which mixed the long and short steel fiber was the most effective for water tightness enhancement in severe environmental conditions.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.764-769
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• 1994

The impedance of an electro-acoustic transducer can be controlled by motional feedback, and the noise in a duct can be reduced actively by adjusting the impedance using an additional sound. In this paper, two approaches for active noise control using motional feedback (MFB) loudspeaker are described. First configuration uses an external sensor to pickup of source directly. In this configuration, the adaptation of controller is necessary to compensate the change of transfer function from noise source to control poing. The second configuration uses a new adaptive algorithm specialized for peridic noise. Because this configuration does not require any reference input and the error sensor couples very tightly with control loudspeaker, this MFB system itself is independent of the duct condition. No microphone are required in both configurations, so that a more reliable and stable active control system can be realized under severe conditions such as high pressure, high temperature, dust, flow and so on.

• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.273-278
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• 2021

Here, we studied the change in the mechanical stiffness of a diaphragm according to the corrugation pattern. The diaphragm consists of a silicon oxide and nitride double layer; a corrugation pattern was formed by dry etching, and the diaphragm was released by wet etching. The fabrication of the thin film was verified using focused ion beam and scanning electron microscopy images. The mechanical stiffness of the diaphragm was obtained by measuring the surface vibration using a laser Doppler vibrometer while applying external sound pressure. Flat squares, diaphragms with square corrugations, and circular corrugation patterns were measured and compared. The stiffness of the diaphragm with a corrugation structure was found to be smaller than that without a corrugation structure; in particular, circular corrugation showed a better effect because of the high symmetry. Furthermore, the effect of corrugation was theoretically predicted. The proposed corrugated diaphragm showed comparable flexibility with the state-of-the-art MEMS microphone diaphragm.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.95-102
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• 2024

Due to technological advances, the cruising speed of high-speed trains is increasing, and aerodynamic noise generated from the flow outside the train has been an important consideration in the design stage. To accurately predict the flow-induced noise, high-resolution generation of sound sources in the near field and low-dissipation of sound propagation in the far field are required. This should be accompanied by a numerical grid and time resolution that can properly consider both temporal and spatial scales for each component of the real high-speed train. To overcome these challenges, this research simultaneously calculates the external flow and acoustic fields of five high-speed train cars of real-scale and at operational running speeds using a threedimensional unsteady Large Eddy Simulation technique. To verify the numerical analysis, the measurements of the wall pressure fluctuation and numerical results are compared. The Ffowcs Williams and Hawking equation is used to predict the acoustic power radiated from the high-speed train. This research is expected to contribute to noise reduction based on the analysis of the aerodynamic noise generation mechanism of high-speed trains.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.240-250
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• 2013

The early detection of suicidal ideation is essential for the prevention of suicide. This study aimed to develop a brief screening tool that can be easily administered in medical settings. The Suicide Risk Screening Tool was designed for use by physicians to provide a screening process that would be reliable, standardized, quick and feasible to implement. A 2-item screening tool was derived from the Screening for Depression and Thoughts of Suicide in the Norton Sound region of Alaska, USA. The scale was modified to reflect the current situation in Korea including the elimination of the personal identification number, and was labeled the Korean Suicide Risk Screening Tool. Its reliability and applicability for medical setting were examined by explanatory study of 7 clinicians. Its validity was examined among a further 325 patients of four different medical institutions, using the results of interviewer-administered survey included demographic, clinical characteristics, and present mental status as the external criterion. A brief 2-item suicide risk screening tool can be used by mental and non-mental health clinicians to accurately detect suicidality in patients.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.466-475
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• 1997

In this paper, an implantable middle ear hearing aids using an electromagnetic transducer which consists of a tiny coil and a magnet is designed, and objective design method to implement a vibrator of the electromagnetic type transducer is proposed. Sound characteristic of the electromagnetic type vibrator is excellent but power transfer rate is lower than that of a ceramic type. To improve power transfer efficiency of system, external and inner part of a middle ear system is designed using FM transmission method. We implemented an experimental set of the designed transducer, inner part, and outer part. Then, we measured vibration characteristics of a metal strip and a temporal bone of a dead body. As the results, we confirmed the advantage of FM method and showed that designed transducer could effectively transmit vibration of amplified input sound pressure to ossicle.

• English Language & Literature Teaching
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• v.8 no.2
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• pp.105-115
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• 2003

The four skills of a language are basically required for a communication. They are very important for a learner to develop the balanced language acquisition. Today both listening and speaking skills are emphasized in the global era rather than reading and writing proficiencies. The reason is really why the learners' communicative competence is more needed than the accurate knowledge of a structure in the language. For this reason, the listening comprehension should be taught effectively using the following strategies. First, the sound difference of a language must be taught. Language is a complicated process to convey the comprehensive meaning combined with the internal and external factors of a language. In other words, the meaning for the sound of language should be transmitted by the unit of vocabulary and syntax. Second, a good listening comprehension requires the familiarity and much experience with a lot of English words to understand English sentences unconsciously. Third, as understanding the structure of language is effective for the listening comprehension, the better listening comprehension can be possible through the meaningful exercise. Fourth, the compound process of listening comprehension requires the comprehensive understanding of language, but not the separate understanding of language. Fifth, the appropriate application of the multimedia courseware helps improve the listening comprehension better than that of the existing audio, video, tape recorder and so on. Using multimedia courseware is useful as follows: A learner is able to take as much lesson as he/she wants. It does take little time to repeat about what he/she takes a lesson. It gives the lively picture with the native speakers' voices. It gives him/her(a learner) a feedback effect continuously through the interaction of computer. It controls his/her lesson in accordance with the level of a learner.

• Journal of The Korean Association of Information Education
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• v.13 no.2
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• pp.205-214
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• 2009

The vocal language which is a symbolic vocal language described external sounds or expressed shape of things in nature, phenomenon, movement, shape of state provided images which can be envisioned in minds and created the mood for the whole writings. As the instructive ways of symbolic vocal language, the activities which refrain one-way translation for lexicon definition and stimulate the thoughts of students and interesting activities such as songs and comic books which students can understand by themselves are needed. Therefore, in this study, these symbolic vocal language is to be developed as the contents of robot for Symbolic Vocal language learning activities and after study activities, the possibility of using robot for education is to be reviewed, comparing changes in definitive areas and achievement after study activities. After the Symbolic Vocal language learning activities using robot and computer, as results of testing three achievement types of words simulated sound, shape, and movement, in study on words simulating sound and shape there was no significant difference. But The study activities simulating words used robot showed significant difference in terms of interest, confidence, and understanding.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.519-527
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• 2016

The demand of construction risk analysis is rapidly increased to improve the competitiveness of construction companies and the sound management of the construction project. However, estimating the amount and uncertainty of the risk is difficult due to the wide range of risks in the construction industry. Moreover, most of the research on risk management of construction risk is only focused on the causes of risk without separate the internal and external risk. This study statistically analysis the internal risk and external risk based on the accidents cases which are caused at construction sites to define the difference and importances of the risk. An accident cause analysis and T-test analysis are carried out to reach the goal of study. The results of the study are expected to be used as a guideline of construction project risk analysis.

• Journal of Korean Philosophical Society
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• v.116
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• pp.181-206
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• 2010

It is widely recognized that human beings have moral responsibility for their actions because they have free will to choose and control their acts. Unlike natural phenomena, however, human acts cannot be interpreted with simple, visible ones. Human acts are quite different from natural phenomena because they come about through a number of complicated, invisible phases taking place in our mind. In addition, human actions are under the influence of internal and external factors. Those various internal and external factors are divided into four sectors as follows; (1) the factors that can fall under control of our free will, (2) the factors in the interim phase that could come under our control, (3) the factors that are partially determined that we cannot choose or control over, and (4) the factors that completely determined, and can't be chosen or controlled. we have to pay attention to the fact that we can choose or control the internal and external factors that influence human action. However, there are still factors that are impossible to choose or control with our will. So it is highly unreasonable to hold accountable for actors by means of the factors that can't be chosen or controlled. Hence, the society should be also accountable for the acts of actors influenced by heredity and environment. For this, Politics should affect the external, undesirable, and uncontrollable factors beyond actors power. Education has to exert its influence over the internal and genetic factors by instilling sound values in human mind, too. It is because happy and desirable future will be possible by giving equal opportunities to us including the youth.