• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.59-64
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• 1992

터빈 블레이드와 같이 회전하는 구조물의 파단은 공진 근처에서 진동이 발 생할 때에 이에 기인하는 피로에 의하여 발생한다. 그러므로 이와 같은 파단 을 피하기 위해서는 설계 단계에서 이론적인 계산에 의하여 구조물의 고유 진동수를 결정하는 것이 상당히 중요하다. 판이 회전을 받게 되면 원심력에 의하여 판의 강성이 증가하므로 고유진동수가 회전하지 않는 판의 고유진동 수보다는 상당히 증가하게 된다. 이에 대한 연구가 국내외에서 상당수 행하 여졌지만, 연구의 대부분이 회전의 영향을 고려하지 않은 정지판(stationary plate)에 대한 것이며 뢰전을 고려한 연구는 극히 제한되어 있다. 또한 회전 의 영향을 고려한 연구의 대부분이 해석 대상을 보로서 단순화 시켰고 해법 으로는 유한요소법과 Ritz법 등을 사용하였다. 이는 블레이드가 지니고 있는 기하학적인 형상과 진동 특성이 해석적인 방법으로 해결하는 데에는 상당한 어려움이 있기 때문이다. 실제적으로는 터빈 블레이드와 같은 회전체의 진동 특성이 설치각이나 비틀림각, 판의 형상비, 회전속도 등의 변화에 의하여 영 향을 받기 때문에 보와 같은 진동 거동을 보이기보다는 판이나 셀과 같은 진동 거동을 보이므로 보다 정확한 해석을 수행하기 위해서는 해석 대상을 판이나 셀로서 취급하는 것이 타당하다. 따라서 본 연구에서는 위와 같은 이 유 때문에 해석 대상을 등방성 사각판과 직교이방성 복합재료 사각판으로 선택하였으며, 구조물의 고유진동수에 영향을 미치는 다음과 같은 인자들을 해석에 고려하였다. 1. 회전속도 (rotational speed) 2. 설치각 (setting angle) 3. 허브의 반경 (hub radius) 4. 판의 형상비 (aspect ratio) 5. 적층순서 (stacking sequence)구조물에 대한 동적실험(dynamic test)을 통하여 단기간에 동적특성을 결정하고 SDM(structure dynamic modification)이나 FRS(force response simulation)를 수행하여 임의의 좌표 공간에 대한 진동수준을 해석적으로 예측할 뿐만 아니라 구조물의 진동제어 를 위한 동적인자를 변경시킬 수 있는 정보를 제공하며 장비를 방진할 경우 신뢰성 있는 전달률을 결정할 수 있다. 실험적으로 철교, 교량이나 건물의 철골구조 및 2층 바닥 등 대,중형의 복잡한 구조물에 대항 동특성을 나타내 는 모빌리티를 결정할 경우 충격 가진 실험이 사용되는 실험장비 측면에서 나 실험을 수행하는 과정이 대체적으로 간편하다. 그러나 이 경우 대상 구조 물을 충분히 가진시킬수 있는 용량의 대형 충격기(large impact hammer)가 필요하게 된다. 이러한 동적실험은 약 길이 61m, 폭 16m의 4경간 교량에 대 하여 동적실험을 수행하여 가능성을 확인하였다. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다. 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but stron

• Korean Security Journal
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• no.11
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• pp.37-60
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• 2006

The area of security service has been maintaining the high growth curve annually by improving security consciousness from increase of the income and the progress of public services's level by the accomplishment in the info-communication field, recently the demand for unmanned security system is extended form commercial purposes into public offices and individual's houses. In addition to, the possible distance of offering services is scheduled to magnify. At the period when security company's influence has been becoming significant, the injustice transaction is the serious factor which obstructs the development of security companies. Therefore, it is urgent thing to devise counterplans to extirpate injustice transactions. There are the legalistic approaches of the breakthroughs against injustice transactions. One thing is settling the standard of the judgment and the other is renovating the provision of injustice transactions. Utilizing the principles of the fair competitions and importing self-obedience programs within the range of trade actions which is permitted by law, acted as the system approach. Moreover, there are such three things which can achieve mutual balances as establishing the range of the permitted action toward business corporations, applying spontaneously the fair competition principles and introducing the system of standard agreements. Gong further, this can establish order of security service areas and control them. Besides, it is possible for every organizations to make and operate the system appropriately by importing the self-observance system.

• Journal of Science and Technology Studies
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• v.18 no.1
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• pp.177-217
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• 2018

This study examines the case of living lab applied in the R&D initiatives for solving societal problems and challenges. It discusses how to use the living lab in national R&D projects. The analyzed cases are 'Develop portable fundus camera for eye disease screening test to resolve health inequalities' and 'Auto-sensing integrated system development in rural pedestrian crosswalk'. As a result of the analysis, both cases were designed as a user participatory R&D structure by utilizing living lab. In other words, living lab has operated as a system that evolves technology-products-services into an infrastructure. It can realize final demand specification, product, service improvement and demonstration through continuous interaction of end users. As a result of the case analysis, the following policy tasks can be derived. First, living lab is a new concept and it is in the early stage of implementation in Korea. Therefore, it is necessary to monitor and evaluate living lab experiments and build suitable models for Korean society by sharing cases and achievements. Second, the strategic niche management are necessary for the introduction of living lab. Third, living lab can be used as a tool to transform the existing technology acquisition centered innovation policy to the policy for customer needs and problem solving. Fourth, there is a need for flexibility and adaptability in strategy and system to correct errors that appear in the living lab processes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.199-207
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• 2016

In this paper, we propose efficient smart indoor emotional lighting control system based on android platform using the biological signal. The proposed smart indoor smart emotional lighting control system were configured as the biological signal measurement device and removable smart wall pad, lighting driver, luminaire. The control system was extracts the emotional language by measured the biological signal, and it was transmitted a control signal to each lighting driver using a bluetooth in the wall pad. The lighting driver were designed to control the lighting device through an expansion board by collected control signal and the illuminance information the surrounding. In this case, the wall pad can be selecting of manual control and the bio signal mode by that indoor emotional lighting control algorithms, and it was implemented the control program that possible to partial control by selecting the wanted light. Experiment results of the proposed smart indoor emotional lighting control system, it were possible to the optional control about the luminaire of required area, and the manual control by to adjustable of color temperature with that the efficiently adjustable of lighting by to biological signal and emotional language. Therefore, were possible to effective control for improvement of concentration and business capability of indoor space business conduct by controlling the color and brightness that is appropriate for your situation. And, was reduced power consumption and dimmer voltage, lighting-current than the existing-emotional lighting control system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.57-70
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• 2006

This paper descWireless Sensor Network consisting of a number of small sensors with transceiver and data processor is an effective means for gathering data in a variety of environments. The data collected by each sensor is transmitted to a processing center that use all reported data to estimate characteristics of the environment or detect an event. This process must be designed to conserve the limited energy resources of the sensor since neighboring sensors generally have the data of similar information. Therefore, clustering scheme which sends aggregated information to the processing center may save energy. Existing multi-hop cluster energy consumption modeling scheme can not estimate exact energy consumption of an individual sensor. In this paper, we propose a new cluster energy consumption model which modified existing problem. We can estimate more accurate total energy consumption according to the number of clusterheads by using Voronoi tessellation. Thus, we can realize an energy efficient cluster formation. Our modeling has an accuracy over $90\%$ when compared with simulation and has considerably superior than existing modeling scheme about $60\%.$ We also confirmed that energy consumption of the proposed modeling scheme is more accurate when the sensor density is increased.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.202-208
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• 2012

Fetal heart rate monitoring is important information to assess fetal well-being. Non-invasive fetal ECG (electrocardiography) can be derived from maternal abdominal signal. And various promising signal processing methods have been introduced to extract fetal ECG from mother's composite abdominal signal. However, non-invasive fetal ECG monitoring still has not been widely used in clinical practice due to insufficient reliable measurement and difficulty of signal processing. In application of signal processing method to extract fetal ECG, it might be lower signal to noise ratio due to time varying white Gaussian noise. In this paper, time varying Kalman smoother is proposed to remove white noise in fetal ECG and its feasibility is confirmed. Wiener process was set as Kalman system model and covariance matrix was modified according to white Gaussian noise level. Modified error covariance matrix changed Kalman gain and degree of smoothness. Optimal covariance matrix according to various amplitude in Gaussian white noise was extracted by 5 channel fetal ECG model, and feasibility of proposed method could be confirmed.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.92-99
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• 2013

As a recent cyber attack has a characteristic that is intellectual, advanced, and complicated attack against precise purpose and specified object, it becomes extremely hard to recognize or respond when accidents happen. Since a scale of damage is very large, a corresponding system about this situation is urgent in national aspect. Existing data center or integration security framework of computer lab is evaluated to be a behind system when it corresponds to cyber attack. Therefore, this study suggests a better sophisticated next generation convergence security framework in order to prevent from attacks based on advanced persistent threat. Suggested next generation convergence security framework is designed to have preemptive responses possibly against APT attack consisting of five hierarchical steps in domain security layer, domain connection layer, action visibility layer, action control layer and convergence correspondence layer. In domain connection layer suggests security instruction and direction in domain of administration, physical and technical security. Domain security layer have consistency of status information among security domain. A visibility layer of Intellectual attack action consists of data gathering, comparison, decision, lifespan cycle. Action visibility layer is a layer to control visibility action. Lastly, convergence correspond layer suggests a corresponding system of before and after APT attack. An introduction of suggested next generation convergence security framework will execute a better improved security control about continuous, intellectual security threat.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.318-327
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• 2017

It is essential for the near-field receiving measurement to make beam pattern and check the performance of a active phased array antenna system. Also, we could obtain compensation value for mono-pulse function through the near-field receive test, however, if the radar has many frequency channel, the test would take long time and hard effort. So it is needed that frequency channels are selected for measurement and calculates the values for other frequency channels to improve efficiency in development and manufacture. In this case, the phase variations in sum and del channels would be checked. The phase measurement includes un-linear characteristic because of wrapping effect. Generally, radars have similar path length in sum and del channel, but if a radar has a electrical length gap between sum and del channel, errors could occur by phase's wrapping effect. In this paper, the interpolation method's error caused by electrical length gap is checked and the effective method for frequency channel selection to avoid wrapping effect is introduced.

• Journal of The Korean Association For Science Education
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• v.35 no.4
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• pp.665-676
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• 2015

In this case study, we analyzed the processes of STEAM lessons conducted by preservice secondary science teachers. Three preservice science teachers at a college of education in Seoul participated in this study. After the workshop for STEAM education, they planned and practiced STEAM lessons. All of the teaching-learning materials were collected before lessons, and their lessons were observed and videotaped. Semi-structured interviews were also conducted before and after their lessons. The processes of STEAM lessons were analyzed while focusing on PCK and PDC. Their difficulties, needs, and views on STEAM education were also studied. It was found that they have taken much efforts to reflect the objectives and characteristics of STEAM education, and prepared teaching-learning materials by searching on the internet and arranging creative contents. Their great difficulty was to determine topics for STEAM lessons. While one preservice teacher satisfied with her lesson perceived STEAM education positively, the others perceived that it would be very difficult to practice STEAM lessons in school. For their STEAM lessons to be successful, the workshop needs to include some specific information on grades, proper topics for each grade, ways of making materials, and tips for effective STEAM lessons. In addition, it will be effective if the workshop is carried out after their study on constructivist learning theory and if they experience successful STEAM lessons.

• 대한공업교육학회지
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• v.34 no.1
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• pp.196-209
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• 2009

The purpose of this study was to analyze engineering basic competencies about the time completed a course and educational needs of engineering college graduates. Survey method using questionnaire was the major research method of this study. A survey of 807 engineering college graduates was carried out. Questionnaire were made of the level of engineering basic competencies of engineering college graduates, its priorities of actual vocation and level of engineering basic competencies of major. Major results of the study, some recommendations for future researches were made as follows: The level of engineering basic competencies of engineering college graduates was 3.3 average(5 full marks). Engineering basic competencies that educational needs were high respectively, were an ability to communicate effectively, an ability to design a system, component, or process to meet desired needs, an ability to function on multi-disciplinary teams, an ability to understand global culture and cooperate internationally, an ability to design and conduct experiment as well as to analyze and interpret data, and an ability to engage in life-long learning.