• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.82-91
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• 2014

The combined generator system by integrating several renewable energy sources can share the electrical infrastructure and therefore have the advantage of constructing not only the transmission system but also the power conversion system. Among the various combined renewable system, the wind power and wave power has a high possibility of future growth due to the economic feasibility in offshore environment. This kind of large-scale combined systems might be follow the determination by the transmission system operator's directions and control the output profile by focusing at PCC. However, both renewable energies are depend on the unpredictable environmental variation; it is needed to do the compensation devices. In this paper, the ESS compensation plan is proposed to do output determination of the combined generator system by paying attention to active power of utility grid with the analysis of the controllable elements of the wind and wave power generator. The improvement of the new application technique of the combined system is confirmed through using the PSCAD/EMTDC. The entire simulation process was designed by adopting the active power control according to the reference signal of TSO.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.506-515
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• 2020

Surfing is a sport sensitive to changes in the natural environment, using naturally occurring waves. In other words, factors such as the construction of coastal structures, coastal erosion, and sediment transportation could cause the wave to change into a direction inappropriate for surfing at the shore where surfable waves were reaching. In this study, we call the characteristics of the coastal environment that affect the formation of surfable waves as surfing resources, which is subsequently analyzed by coastal engineering methodologies. Also, using Delft3D-WAVE module (SWAN model), a way to evaluate sustainability of surfable wave is suggested through analysis of surfing resources at Jukdo, Yangyang, Gangwon Province, Republic of Korea.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.3
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• pp.211-219
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• 2014

Closed cracks are difficult to detect using conventional ultrasonic testing because most incident ultrasound passes completely through these cracks. Nonlinear ultrasound inspection using sub-harmonic frequencies a promising method for detecting closed cracks. To implement this method, a sub-harmonic phased array (PA) is proposed to visualize the length of closed cracks in solids. A sub-harmonic PA generally consists of a single transmitter and an array receiver, which detects sub-harmonic waves generated from closed cracks. The PA images are obtained using the total focusing method (TFM), which (with a transmitter and receiving array) employs a full matrix in the observation region to achieve fine image resolution. In particular, the receiving signals are measured using a laser Doppler vibrometer (LDV) to collect PA images for both fundamental and sub-harmonic frequencies. Oblique incidence, which is used to boost sub-harmonic generation, inevitably produces various surface waves that contaminate the signals measured in the receiving transducer. Surface wave interference often degrades PA images severely, and it becomes difficult to read the closed crack's position from the images. Various methods to prevent or eliminate this interference are possible. In particular, enhancing images with signal processing could be a highly cost-effective method. Because periodic patterns distributed in a PA image are the most frequent interference induced by surface waves, spatial frequency filtering is applicable for removing these waves. Experiments clearly demonstrate that the spatial frequency filter improves PA images.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.182-188
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• 2006

In this study, we have designed the millimeter-wave passive imaging system which records energy that is reflected or emitted from the source and produces image. The lens and front-end of receiver appeared to be important in the system to detect input thermal noise signal. The lens for signal focusing has been designed by optical transfer function. Amplifier of the imaging systemhas been set up with 40dB in maximum gain, 5 dB in maximum noise figure, and 10GHz in bandwidth to enhance sensitivity for thermal noise and to receive it in wide-band width as well. The SBD MSS-20 141B10D diode has been used for the detector circuit to convert amplified millimeter-wave signals to DC output.

• Atmosphere
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• v.33 no.1
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• pp.49-59
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• 2023

Blocking refers to a class of weather phenomena appearing in the mid and high latitudes, whose characteristics are blocked airflow of persistence. Frequently found over the Pacific and Atlantic regions of the Northern Hemisphere, blocking affects severe weather in the surrounding areas with different mechanisms depending on the type of blocking patterns. Along with lots of studies about persistent weather extremes focusing on the specific types of blocking, a new categorization using Rossby wave breaking has emerged. This study aims to apply this concept to the classification of blockings over the Pacific and examine how different wave breakings specify the associated cold weather in the Korean peninsula. At the same time, we investigate a strongly developing ridge around the Pacific by designing a new detection algorithm, where a reversal method is modified to distinguish ridge-type blocking patterns. As result, Kamchatka blocking (KB) and strong ridge over the Central Pacific are observed the most frequently during 20 years (2001~2020) of the studied period, and anomalous low pressures with cold air over the Korean Peninsula are accompanied by blocking events. When it considers the Rossby wave breaking, cyclonic wave-breaking is dominant in KB, which generates low-pressure anomalies over the Korean Peninsula. However, KB with anticyclone wave breaking appears with the high-pressure anomalies over the Korean Peninsula and it generates the warm temperature anomaly. Lastly, the low-pressure anomalies are also generated by the strong ridge over the Central Pacific, which persists for approximately three days and give a significant impact on cold surge on the Korean Peninsula.

• The Southeast Asian review
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• v.21 no.2
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• pp.77-123
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• 2011

Recently, Southeast Asian people, its food, natural sceneries and so on have been increasingly exposed to Korean people through mass media and multi-cultural events. At the same time, Koreans can frequently encounter Southeast Asians in their everyday lives. Thus, specific images and discourses of Southeast Asia has been established in our society, which creates a new social trend called 'Southeast Asia phenomena'. In short, 'Southeast Asia phenomena' means a totality of Korean people's experience of Southeast Asian and their perception on the region. On the one hand, 'Southeast Asia phenomena' is a result of inflow of Southeast Asians and their culture into Korea. On the other hand, it is also a consequence of Korean people's understanding of Southeast Asia from their trip to Southeast Asia or from their interactions with Southeast Asian people. This article aims to analyze the origin and diffusion of 'Southeast Asian Phenomena' in Korea in the context of Southeast Asia focusing on 4 topics, that is, migrant workers, overseas investments, retirement migration, study-abroad categorized as human movement. This article is also about a country-by-country comparative analysis both at the macro level and the micro level. At the macro level, overseas investments and trade, human exchanges, positive perception to Koreans which considered to be the structural causes become a strong mechanism playing a important bridge role between Korea and Southeast Asia. So these create the high probability of the emergence of 'Southeast Asian Phenomena' At the micro level which is more direct causes of 'Southeast Asian Phenomena', the economic cause is the most important common cause for 4 Southeast Asian Phenomena. Additionally, Korean wave is also remarkable common cause creating 'Southeast Asian Phenomena' even it is not the origin in the context of Southeast Asia. The diffusion of 'Southeast Asian Phenomena' is different by the topics and the elements contributing to create the favorable situation for the diffusion are not only overseas investments and trade, human exchanges at the macro level but also policy elements at the micro level. The relative differences of the causes of 'Southeast Asian Phenomena' in the country-by-country analysis are found. Regarding overseas investments in Vietnam and Cambodia, the economic degree of freedom in Cambodia is higher than in Vietnam. Even Korean Wave has had the longer history in Vietnam, but the favorable perspectives on Korean Wave are stronger in Cambodia. For migrant workers from Vietnam and Indonesia, the economic causes in Vietnam are more significant than in Indonesia. The impact of Korean Wave is stronger in Vietnam than in Indonesia. In case of study-abroad, the social-cultural elements and policy elements are more diverse in Malaysia than in Korea. For the Korean retirees who immigrate to the Philippines and Malaysia, the economic causes in the Philippines is more significant in Malaysia.

• Korean Institute of Interior Design Journal
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• v.25 no.2
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• pp.59-69
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• 2016

This study aimed to understand the importance of applying finishing materials into interior space, and to add meaning to the creation of functional space, associated interior finishing materials with brain science. To achieve this purpose, brainwave(EEG) experiment was conducted. The brainwave appearing when sensing the surface of interior finishing materials with hands was measured. The locations of the electrode were FP1, FP2, F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5, T6, CZ, FZ, and PZ and in addition to these, AFZ was added. Eight(8) kinds of finishing materials: metallic material, film paper, lumbar, stone, glass, silk wallpaper, fabric, and paint were used to measure '${\alpha}$-wave against ${\beta}$ wave.' As a result, it was found that the most activated finishing material in term of relaxation was film paper, followed by metallic, glass, paint, fabric, stone, lumbar, and silk wallpaper. To explain in light of this, (1) '${\alpha}$-wave against ${\beta}$ wave' was the most activated at ch1-FP1 and ch2-FP2, and at ch17-AFZ and ch19-FZ, which indicated that metopic-prefrontal lobe showed the highest activation in relaxation. Film paper, among the finishing materials, showed the highest increase in relaxation. (2) In general, '${\alpha}$-wave against ${\beta}$ wave' relaxation was inhibited at ch13-T3 and ch14-T4, and at ch15-T5 and ch16-T6 and the arousal in the temporal lobe was prominent. Silk wallpaper, among the finishing materials, showed the highest arounsal effect. As a result of measuring the superficial touch on the silk wallpaper, which was regarded as the most rough material among the eight finishing materials, the arousal effect of ${\alpha}$-wave against ${\beta}$-wave, among the brainwave characteristics, was found to be the highest. (3) to judge from the scope of this experiment regarding the tactile sensation over the finishing materials, it is considered that the brainwave reaction sometimes appeared contrastive depending on whether the surface was smooth or rough and there also appeared a difference in relaxation and arousal reaction of the brainwave depending on whether the surface was hot or cold, but the sensation on the surface texture was often evaluated differently depending on who you were. For this reason, this study has some limitations.

• Journal of IKEEE
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• v.28 no.3
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• pp.465-468
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• 2024

In this paper, we propose a synthetic aperture radar based on FMCW using a nonlinear radar platform. we construct a nonlinear radar platform with different transmit and receive frequencies using FMCW signals. The platform moves along a 1.5 m path to acquire second harmonics signals, implementing a nonlinear SAR (synthetic aperture radar). Multiple nonlinear targets were placed in an indoor multipath environment with linear objects to detect weak second harmonics. After undergoing the SAR focusing precess, a 2D hamming window was applied to enhance the focusing performance.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.403-414
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• 2004

In the accompanying paper, we proposed a real. time volumetric imaging method using a cross array based on receive dynamic focusing and synthetic aperture focusing along lateral and elevational directions, respetively. But synthetic aperture methods using spherical waves are subject to beam spreading with increasing depth due to the wave diffraction phenomenon. Moreover, since the proposed method uses only one element for each transmission, it has a limited transmit power. To overcome these limitations, we propose a new real. time volumetric imaging method using cross arrays based on synthetic aperture technique with linear wave fronts. In the proposed method, linear wave fronts having different angles on the horizontal plane is transmitted successively from all transmit array elements. On receive, by employing the conventional dynamic focusing and synthetic aperture methods along lateral and elevational directions, respectively, ultrasound waves can be focused effectively at all imaging points. Mathematical analysis and computer simulation results show that the proposed method can provide uniform elevational resolution over a large depth of field. Especially, since the new method can construct a volume image with a limited number of transmit receive events using a full transmit aperture, it is suitable for real-time 3D imaging with high transmit power and volume rate.

• Journal of Engineering Education Research
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• v.19 no.5
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• pp.57-64
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• 2016

This study is about interdisciplinary education model of using Davis Guggenheim's documentary film on global warming which is a big concern in climate change issues, An Inconvenient Truth. It based on Al Gore's slide speech. Through a course student analyzed the cause and phenomenon of global warming resulted from increase of $CO_2$ by using fossil fuel and its environmental science effects-heat wave, desertification, tornado, hurricane, sea level rise caused by melting glaciers, destroying ecosystem like habitat degradation of wild animals, for example polar bear, extreme cold wave caused by change of ocean currents- of global warming. After, student discussed of efforts to prevent global warming. This educational model is appropriate for lower grade student of environmental engineering and also available for converged majors or general education class.