• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.155-158
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• 2008

본 논문에서는 2D CAT (Two dimensional Cellular Automata Transform)을 이용한 새로운 블라인드 워터마킹 방법을 제안한다. 먼저 GV (Gateway Values)로 기저함수를 만들고 그것을 이용하여 원 영상을 CA (Cellular Automata) 영역으로 변환한다. 그 후 변환 영역의 특정부분에 랜덤 시퀀스를 워터마크로 삽입한다. 제안방법에서 2D CAT 기저함수는 한 개의 GV에 의해 유일하게 하나가 존재하며 가능한 GV의 종류는 $2^{96}$개가 있기 때문에 뛰어난 보안성 (security)을 가진다. 워터마크 된 영상은 충실도가 기존의 주파수 영역의 방법보다 높을 뿐만 아니라 JPEG 압축, 필터링, 첨예화, 노이즈 등 공격에도 강인성 (robustness)을 가지고 있음을 증명한다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권6호
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• pp.1056-1063
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• 2015

Waves can be expressed in terms of a spectrum; that is, the energy density distribution of a representative wave can be determined using statistical analysis. The JONSWAP, PM and BM spectra have been widely used for the specific target wave data set during storms. In this case, the extracted wave data are usually discontinuous and independent and cover a very short period of the total data-recording period. Previous studies on the continuous wave spectrum have focused on wave deformation in shallow water conditions and cannot be generalized for deep water conditions. In this study, the Generalized Extreme Value (GEV) function is proposed as a more-optimal function for the fitting of the continuous wave spectral shape based on long-term monitored point wave data in deep waters. The GEV function was found to be able to accurately reproduce the wave spectral shape, except for discontinuous waves of greater than 4 m in height.

• 대한건축학회논문집:계획계
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• 제34권7호
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• pp.79-88
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• 2018

In the late Koryo Dynasty~early Joseon Dynasty, nationwide distribution of Ondol prompted the formation of ㄱ-shaped corner space. From this background, the spatial form changed according to the space function. In the case where the ondol is located in the bent portion, it would have formed a similar spatial form nationwide at the beginning of the 16th century. Until the middle of the 16th century the receptionists and the family rituals were carried out in the inner of the house, so ㄱ-shaped corner space gradually expanded. Also a special structure type using fultile rafters was used to cover the upper structure of the extended folded space. From the 17th century, ㄱ-shaped corner space was varied from wide and high to narrow and low. In addition to this, the space function of ㄱ-shaped corner is a small hall, a wooden floored room, and the kitchen. And Their spatial form also changes over time.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.169-172
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• 2008

Land-use or land-cover classification of satellite images is one of the important tasks in remote sensing application and many researchers have been tried to enhance classification accuracy. Previous studies show that the classification technique based on wavelet transform is more effective than that of traditional techniques based on original pixel values, especially in complicated imagery. Various wavelets can be used in wavelet transform. Wavelets are used as basis functions in representing other functions, like sinusoidal function in Fourier analysis. In these days, some basis functions such as Haar, Daubechies, Coiflets and Symlets are mainly used in 2D image processing. Selecting adequate wavelet is very important because different results could be obtained according to the type of basis function in classification. However, it is not easy to choose the basis function which is effective to improve classification accuracy. In this study, we computed the wavelet coefficients of satellite image using 10 different basis functions, and then classified test image. After evaluating classification results, we tried to ascertain which basis function is the most effective for image classification. We also tried to see if the optimum basis function is decided by energy parameter before classifying the image using all basis function. The energy parameter of signal is the sum of the squares of wavelet coefficients. The energy parameter is calculated by sub-bands after the wavelet decomposition and the energy parameter of each sub-band can be a favorable feature of texture. The decision of optimum basis function using energy parameter in the wavelet based image classification is expected to be helpful for saving time and improving classification accuracy effectively.

• 한국화재소방학회논문지
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• 제20권3호
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• pp.35-41
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• 2006

본 논문에서는 22.9 kV용 변압기 부싱 절연 커버의 실태조사를 실시하였다. 절연 커버에 열적 스트레스를 인가하여 열화 패턴, 열 중량 변화, 적외선 특성 등을 해석하여 전기사고 원인 분석을 위한 근거를 제시하고자 한다. 노출된 변압기 단자를 보호하기 위해 설치한 절연 커버의 크기 및 길이가 부적절한 것이 확인되었다. 절연 커버에 $150^{\circ}C$의 열적 스트레스를 인가한 경우 플라스틱 절연 커버(A, B, D, E)는 심한 변형이 일어났으나, 고무 절연 커버 C는 정상이었다. 열 중량 분석 결과 절연 커버 A는 $307.8{\sim}405.9^{\circ}C$에서 33.3%의 감소가 있었으며, 절연 커버 C는 $258.8{\sim}332.9^{\circ}C$에서 53.7%의 감소가 발생하였다. FT-IR 분석에서 플라스틱 절연 커버는 $CH_2,\;CH_3$, C=O, C=C 결합 구조를 갖는 것으로 나타났으며, 고무 절연 커버는 OH, $CH_2,\;CH_3$, C=O, C=N, C=C 등의 결합인 것을 알 수 있었다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.248-258
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• 2003

Finite element computations were carried out to study the indentation by rigid cone with half-angle of $70.3^{\circ}$ for 72 different combinations of elasto-plastic properties that cover the wide range of mechanical parameters of common engineering solid materials. The dimensional analysis and representative strain concept were used in the analysis. It was shown that for the same representative strain value, the loading curvature C can be formulated under two different forms, which are based on two alternative dimensionless functions. The present study's one is simpler than the other previously found by other authors using the similar approach. For a wide range of material's parameters, the hardness-modulus ratio should be a parabolic function of ${\sigma}E$, rather than a power law function earlier proposed.

• 대한화학회지
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• 제36권2호
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• pp.329-334
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• 1992

단백질 수용액 중의 초음파흡수 mechanism을 규명하기 위하여 pH 7의 소혈청 albumin(BSA)수용액의 초음파흡수 측정을 주파수 100 kHz에서 1600 MHz에 걸쳐 행하였다. 측정방법은 plano-concave 공명법(0.1${\sim}$10 MHz)과 고분해능 Bragg 반사법(120${\sim}$1600 MHz)을 사용하였다. pH7에서의 초음파흡수스펙트럼은 Davidson-Cole 분포식의 거울상인 분포함수를 사용한 완화곡선과 일치하였다. 이 완화현상을 BSA 분자의 수화평행에 의한 것으로 해석하였다.

• 소성∙가공
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• 제9권6호
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• pp.590-597
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• 2000

A finite element formulation lot the simulation of axisymmetric sheet hydroforming is proposed, and an implicit program is coded. In order to describe normal anisotropy of steel sheet, Hill's non-quadratic yield function (Hill, 1979) is employed. Frictional contacts among sheet surface, rigid tool surface, and flexible hydrostatic pressure are considered using mesh normal vectors based on finite element of the sheet. Applied hydraulic pressure is also considered as a function of forming rate and time and treated as an external loading. The complete set of the governing relations comprising equilibrium and interfacial equations is approximately linearized for Newton-Raphson algorithm. In order to verify the validity of the developed finite element formulation, the axisymmetric bulge test is simulated. Simulation results are compared with other FEM results and experimental measurements and showed good agreements. In axisymmetric hydroforming processes of a disk cover, formability changes are observed according to the hydraulic pressure curve changes.

• 정보보호학회논문지
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• 제6권4호
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• pp.53-66
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• 1996

World Wide Web is a total solution for multi-media data transmission on Internet. Because of its characteristics like ease of use, support for multi-media data and smart graphic user interface, WWW has extended to cover all kinds of applications. The Secure Information Center(SIC) is a data transmission system using conventional cryptography between client and server on WWW. It's main function is to support the encryption of sending data. For encryption of data IDEA(International Data Encryption Algorithm) is used and for authentication mechanism MD5 hash function is used. Since Secure Information Center is used by many users, conventional cryptosystem is efficient in managing their secure interactions. However, there are some restrictions on sharing of same key and data transmission between client and server, for example the risk of key exposure and the difficulty of key sharing mechanisms. To solve these problems, the Secure Information Center provides encryption mechanisms and key management policies.

• 복식
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• 제51권2호
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• pp.93-103
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• 2001

This Study shows local characters, meaning, value and others (kind, function, material, shape, name) on Shroud through documents and fact-finding survey. In Shroud′s kind and function, Shroud of Kwangju Area is similar with one of Youngsan-river Area, while Sumjin-river Area and Coastal Area, each has its own character due to difference of Burial Culture. In Shroud′s Material, hemp cloth, white cotton cloth and calico, have been well-used in Kwangju and Youngsan-river Area, while silk has used in Sumjin-river and Coastal Area. Shroud′s color has followed Natural color. In Shroud′s shape, Male Jeoksam, Female Trousers, Um, Myokmok, Aksoo, Bib have their local characters. They are reformed in Kwangju Area and Youngsan-river Area. Jeoksam in Coastal Area, Female Trousers in Sumjin-river Area. Um in Coastal Area and Myokmok in Sumjin-river Area, have its unique character. In Shroud′s name, Shroud has widely been called "Dead Clothes", and called "Blind Clothes", "Munnyung Clothes" some areas. In Sumjin-river Area, Summer Jacket has been failed "Deungjigae", Dango called "Ddangjungwee". In Coastal Area, Myokmok and Aksoo have been called "Face Cover" and "Hands Cover", Shroud′s local characters have been caused by Next World, which has reflected local natural environment and cultural features. Next World is so abstract that it can not be expressed well, while Reality is clearly divided into dual spaces : Real World, Next World. Comprehension on Next World, helps harmonize recent values with Shroud meaning and prevents Shroud from standardization and transformation.