• 대한전기학회논문지
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• 제36권1호
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• pp.52-57
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• 1987

In this paper, a methodology is developed to remove the reaching phase and the high frequency chattering phenomenon which are the common drawbacks of variable structrue control (VSC) system. A time varying switching surface is proposed to achieve sliding motion during the entire control process and a continuous control law whose terms are continuous functions inside a boundary layer neighbouring the time varying switching surface is developed to remove the high frequency chattering phenomenon of VSC. The methodology developed in this paper is applied to the 2'nd order time varying system and the simulated results are compared with those of typical VSC methodology.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.47-53
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• 2017

우주 발사체의 발사 실패 원인 중 가장 대표적인 것이 연소불안정 현상이다. 연소불안정은 연소실 내부의 압력 섭동과 열방출 섭동의 상호작용으로 인하여 연소실 내부의 압력 섭동이 크게 증폭되는 현상을 말하며, 이러한 현상이 심해지게 되면, 엔진의 폭발 또는 비행체의 추락 등이 일어나게 된다. 이러한 연소불안정 현상을 예측하고 회피하기 위해서는 현상의 이해가 반드시 필요하며, 이를 위해 국내외적으로 연소불안정에 대해 수치적, 이론적, 실험적인 접근을 통한 연구가 많이 진행되고 있다.

• 대한전기학회논문지:전력기술부문A
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• 제55권4호
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• pp.163-171
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• 2006

This paper presents a definition of sync phenomenon occurring in power systems, and describes the characteristics of sync in basic electric circuits. In addition, sync observed in basic circuits was extended to the analysis of dynamic characteristics in power systems. This paper, moreover, describes the sync occurring among system outputs from time domain simulation for two-area systems. In power systems, sync is a common phenomenon that is always observed among generator powers or bus voltages. Thus, we can use sync to obtain the characteristics of power systems without being bound to a specific operating point. Sync can be useful information in power system operation and planning.

• Medical Lasers
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• 제9권1호
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• pp.62-64
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• 2020

Psoriasis is a common chronic inflammatory skin disease that is histopathologically characterized by abnormal differentiation and hyperproliferation of keratinocytes, infiltration of T lymphocytes, and alternations of the dermal vasculature. Pulsed dye laser (PDL) is commonly used to treat cutaneous vascular lesions, and it has been studied for the treatment of localized psoriatic lesions. A 30-year-old female patient with refractory psoriasis on her forehead was treated using PDL. After two sessions, the size of the psoriatic lesion increased, which might have occurred due to koebnerization. As the patient continued to receive PDL treatment, the lesion showed significant improvement with no recurrence on the one-year follow-up. We present here a case of refractory psoriasis treated with PDL and demonstrates an association between a delayed therapeutic effect and the Koebner phenomenon.

• Current Optics and Photonics
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• 제7권6호
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• pp.755-760
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• 2023

In this paper, an illumination optical system that can mitigate the saturation phenomenon in the center of an image (caused by the typical flexible-endoscope illumination system using LEDs with Lambertian light distribution) is designed. When an LED with Lambertian light distribution is used as a light source, the amount of light in the center of the endoscopic illumination system is relatively high, compared to the periphery, causing saturation in the image. Since this phenomenon causes difficulty in detecting the patient's lesion, it is necessary to find a lighting-system design that can alleviate the saturation phenomenon. Therefore, in this paper a lighting system with bat-wing light distribution, which can lower the intensity at the center and secure the maximum amount of light at the maximum light distribution angle, is designed. In addition, to check the performance of the designed lighting system, a simulation of illumination and luminance is conducted for a system using a common aspherical lens with otherwise the same components. As a result, it is confirmed that the lighting system designed in this paper effectively reduces the luminance value at the center and secures more luminance values at the periphery than the familiar lighting system.

• 한국실내디자인학회논문집
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• 제15권4호
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• pp.29-36
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• 2006

Fashion and interior architecture are two areas of design that may share common issues, trends and philosophies, making fashion design human's second skin and interior architecture the third. The concept of 'skin' has become one of the most interesting phenomena in design during the past decade and not surprisingly similar issues can be seen also in fashion and architectural design. The current trend in fashion design is that the skin (clothing) has become detached from the human body and extended into the environment, resulting fashion as art objects. Skin in architecture and interior design has also become detached from the structure so designers have more freedom to experiment by using advanced technologies. The present study attempts to analyze common features of 'skin phenomenon' in fashion and interior architecture that are; detachment, emphasis on space, extension, territorial blending, and digital applications. The researcher has used constant comparative method to categorize the five features among many examples. The limitation of this study is that it is focused on the formative phenomena of projects excluding the philosophies and personal background of each designer. However, it is hoped that the study may assist designers and other researchers to understand relationships between fashion and interior design, hold broader spectrum in art and design.

• 생태와환경
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• 제41권2호
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• pp.247-263
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• 2008

A two-dimensional (2D) reservoir hydrodynamics and water quality model, CE-QUAL-W2, is employed to simulate the hydrothermal behavior and density current regime in Andong Reservoir. Observed data used for model forcing and calibration includes: surface water level, water temperature, dissolved oxygen and suspended solids concentration. The model was calibrated to the year of 2003 and verified with continuous run from 2000 till 2004. Without major adjustments, the model accurately simulated surface water levels including the events of large storm. Deep-water reservoirs, like Andong Reservoir, located in the Asian Monsoon region begin to stratify in summer and overturn in fall. This mixing pattern as well as the descending thermocline, onset and duration of stratification and timing of turnover phenomenon were well reproduced by the Andong Model. The temperature field and distinct thermocline are simulated to within $2^{\circ}C$ of observed data. The model performed well in simulating not only the dissolved oxygen profiles but also the metalimnetic dissolved minima phenomenon, a common1y occurring phenomenon in deep reservoirs of temperate regions. The Root Mean Square Error (RMSE) values of model calibration for surface water elevation, temperature and dissolved oxygen were 0.0095 m, $1.82^{\circ}C$, and $1.13\;mg\;L^{-1}$, respectively. The turbid storm runoff, during the summer monsoon, formed an intermediate layer of about 15 m thickness, moved along the metalimnion until being finally discharged from the dam. This mode of transport of density current, a common characteristic of various other large reservoirs in the Asian summer monsoon region, was well tracked by the model.

• 한국의상디자인학회지
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• 제21권3호
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• pp.137-147
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• 2019

The purpose of this study, I investigate the new trend, 'new-tro', through the music video costumes of young generations, and analyze the meaning and characteristics of 'new-tro'. The research method is, select 30 music video with new-tro fashion style on the music sites, and the fashion styles were analyzed in 11 music videos checked and selected by 100 students. As a definition of the term, 'retro' refers to a phenomenon in which the past reappears in modern time, and 'new-tro' is a new retro trend, a social phenomenon that enjoys the old with a modern sense, and is a compound word of 'new' and 'retro'. 'new-tro' is a modern reinterpretation and rebirth of the past style, and 'fu-tro' is a style of coexistence between the past and the future. In the music video, fashion is a media language and cultural code, and it creates trend or new fashion, that communicates with the public, stimulating emotions. As a result of the research, the common trend phenomenon expressed in the music video costume of 'new-tro' trend which appeared in 2000s is as follows. 1. New-tro style starts with items that were famous in the past. 2. It is one of postmodern marketing using color, print and logo. 3. It spreads quickly by the influence of culture that is characteristic of the Internet and SNS world. 4. It is bottom up propagation phenomenon of street fashion. 5. It is a time game where modern people connect the past with the present. 6. "new-tro" continues to evolve for that time, based on 'retro'. New-tro, an evolutionary version of the 21st century retro wave. and it is a key to marketing effectiveness as a sympathetic elements of 1020 generations with the reproduction of memories.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.504-508
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• 2009

To obtain high power, diesel engines continuously increase combustion pressure and mean effective pressure each cylinder, and the excitation sources and noisy sources are increased, too. Moreover, to reduce the costs, shipyards make hull structures weaker than before. As above reasons, it is more difficult to control the vibration phenomenon nowadays. In this study, it was investigated why diesel generator sets reached the vibration allowable limits during the FAT and heavy vibration phenomenon of diesel generator sets using ODS test during onboard tests. Also, it is found out the stiffness of deck and common bed using the test result of their structural impedance. To find out the vibratory characteristics of diesel generator sets, MODAL tests were carried out. From the sensitivity analysis after above tests, it was selected points to be reinforced and studied troubleshooting to solve heavy vibration phenomenon of diesel generator sets.

• Computers and Concrete
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• 제31권4호
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• pp.277-292
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• 2023

Much of our experiments are designed to uncover the cause(s) and effect(s) behind a phenomenon (i.e., data generating mechanism) we happen to be interested in. Uncovering such relationships allows us to identify the true workings of a phenomenon and, most importantly, to realize and articulate a model to explore the phenomenon on hand and/or allow us to predict it accurately. Fundamentally, such models are likely to be derived via a causal approach (as opposed to an observational or empirical mean). In this approach, causal discovery is required to create a causal model, which can then be applied to infer the influence of interventions, and answer any hypothetical questions (i.e., in the form of What ifs? Etc.) that commonly used prediction- and statistical-based models may not be able to address. From this lens, this paper builds a case for causal discovery and causal inference and contrasts that against common machine learning approaches - all from a civil and structural engineering perspective. More specifically, this paper outlines the key principles of causality and the most commonly used algorithms and packages for causal discovery and causal inference. Finally, this paper also presents a series of examples and case studies of how causal concepts can be adopted for our domain.