• 비파괴검사학회지
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• 제35권1호
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• pp.39-45
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• 2015

지능형 센서 기반의 구조 건전성 감시를 통해 안전성을 확보하기 위한 연구는 우주항공을 비롯하여 기계/토목 구조물, 수송 기계 분야로 확대되었다. 특히, 실시간으로 운용되는 구조물은 사고로 인한 재산 및 인명 피해를 예방하기 위해 여러 스마트 센서 기반의 구조 건전성 감시 기술이 요구되는 결과로 이어졌다. 한편, 상용화되어 있는 대부분의 센서는 전자기 기반의 센서로써 전자기 간섭 및 부식과 같은 적용성의 제한과 환경적 요인에 취약할 수 있다. 따라서, 전자기 기반 센서의 단점을 보완하기 위한 신개념 센서로 광섬유 센서가 최근 각광을 받고 있다. 하지만, 광섬유 센서를 이용한 실제 구조물의 감시를 위해서는 고가 장비와 시스템이 요구되어 어려움이 존재한다. 따라서, 본 연구에서는 한 가닥의 광섬유를 이용하여 여러 지점에서 발생할 수 있는 충격을 검출하는 센서 시스템을 제안하였다. 이를 위해, 광섬유 굽힘 손실 현상을 이용하여 같은 충격에 대해 위치별 광 강도의 변화량 차이가 존재하도록 센서부의 모듈을 제작하였다. 그리고, 광 강도 변화에 영향을 미치는 변수들을 이용하여 실험 설계를 하였으며, 충격 위치 검출이 가능함을 실험적으로 검증하였다.

• 한국실내디자인학회논문집
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• 제24권1호
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• pp.3-11
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• 2015

I paid attention to the fact that surrealism emerging in early 20th century has been resurfacing in the 21st century. It may be because of the increasing interest on the space showing the surrealistic features as people in these days prefer the experimental and dramatic space beyond repetitive daily life. I tried to identify the expressive characteristics in the interior space adopting the depaysement technique among a variety of expression techniques of surrealism. To this end, this paper selected 10 interior design projects by Fabio Novembre and Marcel Wanders since 2000s. As the methodology, chapter 2 examined the theories to identify the expression targets and approaches of depaysement around the art paintings. Next, the standard for case analysis in this paper was established by investigating the existing theses related to interior and space design with depaysement as the key word. The expressive characteristics of depaysement identified from the existing researches were classified into morphological, figurative, material and space program. Those programs were developed as the classification system in this paper. Chapter 3 described the design background and features of Fabio Novembre and Marcel Wanders. On the basis of the features and analysis framework identified in chapter 2 and 3, chapter 4 analyzed the features of depaysement observed in the works by both designers. The conclusion was presented in chapter 5. For the expressive characteristics of depaysement observed in the space by both designers, Novembre created optical illusion using distortion or overlap on the morphological aspect. Wanders showed mainly the feature of changing the scale. In accordance with the analysis on expression principles, the features including spatial continuity, ambiguity of border, visual amusement and uncertainty were differentiated in all spaces.

• The Journal of Advanced Prosthodontics
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• 제3권4호
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• pp.196-203
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• 2011

PURPOSE. This study evaluated marginal fit of glass infiltrated alumina cores fabricated using two techniques and their marginal stability after firing cycles of veneering porcelain. MATERIALS AND METHODS. Fifteen standardized all-ceramic crowns were fabricated on a metal die using each technique: slip cast technique of VITA In-Ceram sprint Alumina (Group A as control) and plastic foil matrix technique of Turkom-Cera fused alumina core system (Group B). Copings were compared between groups and within groups at coping stage and after firing each layer of veneering porcelain. A device was used to standardize seating of copings on the metal die and positioning of the specimens under the microscope after each stage of fabrication. The specimens were not cemented and marginal gap was measured using an image analyzing software (Imagepro Express) on the photographs captured under an optical microscope. Two tailed unpaired 't test' was used to compare marginal gaps in two groups and one way ANOVA was used to analyze marginal distortion within each group at 95% confidence interval. RESULTS. The marginal gap was smaller at the coping stage in group B ($60+30{\mu}M$) than group A ($81+21{\mu}M$) with statistical significance. After firing of veneering porcelain the difference was insignificant. At the final stage, both groups exhibited lower mean marginal gaps than at the initial coping stage with the difference of $11.75{\mu}M$ for group A and $11.94{\mu}M$ for group B, but it was statistically insignificant due to high value of standard deviation. CONCLUSION. Within the limitations of this study, it was concluded that both techniques produced copings with comparable and acceptable marginal fit and marginal stability on firing veneering porcelain.

• 한국가구학회지
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• 제23권3호
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• pp.324-331
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• 2012

The domestic pine was used to investigate the change of specific gravity, moisture contents, color and anatomical structure by accelerated weathering test (AWT). According to visual inspection, a few knot separation and looseness as well as considerable surface discoloration was found out. However, the crack and split of surface texture have been never occurred till the last step of AWT. On the whole, as the time of accelerated weathering test has increased, the specific gravity has decreased. Finally, after the 9th week of AWT, the specific gravity was 0.38 that reached to 82% compared to the control specimen. In case of moisture content (MC), it showed rising trend in its early stages, however, after 3th week of AWT it have displayed steady state. A deterioration of cell-wall components was not remarkably observed by scanning electron microscope (SEM), however the ray fractures of AWT specimen were observed more than those of control specimen. The full fracture of epithelial cell around resin canal was observed by optical microscope. The fracture of ray of 2th cycle AWT specimen was first, followed by 1th week and control group. A distortion of tracheid for early spring wood and fracture of epithelial cell were generally observed by a similar level, regardless of duration time of AWT. Therefore, it is obvious that increasing duration time of AWT does not affect the deterioration of micro-structure for wood members from this study. Although a considerable change of anatomical properties was not found, there is a need of further research to understand how will the changes of specific gravity and MC on the physical properties of wood member.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.333-336
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• 2001

본 논문에서는 1.3$\mu\textrm{m}$ 대역에서 증폭특성을 갖는 PDFA의 과도응답 특성을 이론적으로 해석하였다. 수치모델은 밀도반전의 형성과정, 여기파워, 신호파워와 증폭기를 따라 변화하는 신호파워를 포함하고 광섬유 증폭기의 길이에 따른 각 에너지준위의 밀도, 여기파워, 이득의 해서과 시간의 변화에 따른 각 에너지준위의 밀도변화와 이득을 해석하였다. 이러한 수치해석의 결과는 광섬유증폭기의 이득 포화와 복구시간을 예측할 수 있게 해주고, 이득의 포화와 복각시간이 광 펄스의 증폭에 미치는 영향을 예측한 수 있게 한다. 시뮬레이션의 결과, 여기광의 파장 1.017$\mu\textrm{m}$, 파워 0.5W이고 광섬유증폭기의 Pr 이온의 도핑농도가 1000ppm일 경우 광섬유증폭기의 길이 약 5m 에서 이득의 포화가 이루어 졌으며 30dB의 이득을 얻었다. 또한 상준위의 이온밀도는 약 250$\mu\textrm{s}$의 시간이 지난후에 포화됨을 알 수 있었다.

• 한국해양학회지:바다
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• 제3권4호
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• pp.228-233
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• 1998

본 연구는 비측량용 사진기를 이용한 근거리 사진측정법을 적용하여 해빈단면을 추정하는 방법을 제시한다. 수평면 위에 고정된 비디오로부터 획득한 경사비디오영상을 해석하는 방법을 기초로 다음 두 가지 관점을 고려하여 경사사진 해석에 적합한 방정식을 유도하였다. (1) 사진기가 광축에 대하여 회전되는 것을 허용하였다. (2) 정확도를 향상시키기 위하여 렌즈왜곡을 비롯한 사진 계통상의 오차를 보정하는 단순한 오차모형을 도입하였다. 수정된 방정식을 검증하기 위하여 1998년 2월에 동해시 해빈에서 사진촬영과 정밀한 수준측량을 수행하였다. 그 결과 근거리 사진측정을 통한 해빈단면 추정값과 실제 측량값 사이의 수직거리에 대한 RMS 오차는 10 cm 이내였다.

• 한국의류학회지
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• 제40권4호
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• pp.600-614
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• 2016

This study specifies the definition and characteristics of fake fashion by categorizing cases through an analytical framework that uses the concept of simulacre, which is one of the theories that explains the reproduction of images and symbols in a modern consumer society. The presentation stages of modern fake fashion based on Baudrillard's concept of simulacre are as follows: Stage 1 focuses on the realistic imitation of the original, Stage 2 maintains a similarity with the original while transforming through the distortion of shape or visual perception, Stage 3 is the reality of the original which has become significantly vague and actively involves the designer's creativity, and Stage 4 forms a new value and an independent aura beyond reproducing the original. The presentation techniques of modern fake fashion viewed in the concept of simulacre can be classified into optical illusions by reproduction, use of a fake object, use of unusual shapes, and re-signifying through borrowing. As a result of applying the collected cases to the analytical framework, image reproduction in Stage 1 with imitative nature is a counterfeit that cannot be regarded as fake fashion, and fake fashion in Stage 4 (that can be referred to as simulacre) is fashion with symbolic and multiple meanings with new and creative designs. Modern fake fashion analyzed in the concept of simulacre transforms or reproduces the preexisting original with the purpose of merely creating original designs as well as acts as a new symbolic signal that creates a new aura and sets a trend with a message.

• 한국광학회지
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• 제31권4호
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• pp.169-175
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• 2020

격자의 구조가 간단하고 격자의 대조비가 낮은 SBC 시스템 구성을 위한 무편광 유전체 다층박막 회절격자를 설계하였다. SBC 방법으로 결합한 빔의 빔 품질을 높게 유지하기 위하여 회절격자의 파면 왜곡이 최소화되는 구조를 제안하였으며, 오염에 의한 흡수가 발생하지 않고 회절격자를 제작할 수 있는 구조로 회절격자를 최적화 설계하였다. 설계된 회절격자는 1055 nm 중심파장에서 Littrow 각도로 입사하는 경우 무편광 -1차 회절 효율이 99.36%이었으며, 96% 이상의 무편광 회절 효율을 나타내는 공정 여분이 확보되어 있음을 확인하였다.

• 한국광학회지
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• 제6권4호
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• pp.288-295
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• 1995

무한한 Fresnel number를 갖는 imaging unstable ring resonator에 의한 펄스형 Nd:YAG 레이저 출력 광속의 위상파면을 분석하였다. 본 연구를 위하여 4개의 평면경과 망원경을 포함하는 Negative Branch Unstable Ring Resonator(NBUR) Nd:YAG 레이저를 제작하였다. NBUR 공진기 내에서 증폭되는 광속이 scraper mirror의 원형 투과창을 통해 투과하는 과정에서 발생하는 회절효과는 광학 공진계에 self imaging 조건을 줌으로서 크게 감소시킬 수 있었다. 이러한 self imaging 광속이 고리형 공진계를 반복적으로 진행함으로서 위상파면의 공간적 가간섭성이 향상 되는 것으로 해석 되었다. 레이저 출력 광속의 공간적 위상파면 정보는 Mach-Zehnder 간섭계에 의하여 얻어지는 간섭무늬를 이용하여 얻었으며 이 간섭무늬를 Fourier 변환 방법으로 분석한 결과, 위상파면 왜곡정도가 0.2.lambda.이하 값임을 측정하였다. 이것을 정상파형 레이저 공진기에서의 출력 광속과 비교한 결과 공간적 가간섭성이 75% 정도 향상되었음을 확인하였다.

• International Journal of Contents
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• 제5권3호
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• pp.50-56
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• 2009

Internet is being used for several activities by a great range of users. These activities include communication, e-commerce, education, and entertainment. Users are required to register regarding website in order to enroll web activities. However, registration can be done by automated hacking software. That software make false enrollments which occupy the resources of the website by reducing the performance and efficiency of servers, even stop the entire web service. It is crucial for the websites to have a system which has the capability of differing human users and computer programs in reading images of text. Completely Automated Public Turing Test to Tell Computers and Human Apart (CAPTCHA) is such a defense system against Optical Character Recognition (OCR) software. OCR can be defined as software which work for defeating CAPTCHA images and make countless number of registrations on the websites. This study proposes a new CAPTCHA context that is Korean CAPTCHA by means of the method which is splitting CAPTCHA images into several parts with random rotation values, and drawing random lines on a grid background by using Korean characters only. Lines are in the same color with the CAPTCHA text and they provide a distortion of image with grid background. Experimental results show that Korean CAPTCHA is a more secure and effective CAPTCHA type for Korean users rather than current CAPTCHA types due to the structure of Korean letters and the algorithm we are using: rotation and splitting. In this paper, the algorithm of our method is introduced in detail.