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프랙탈의 반복함수계를 이용한 웨이블릿 기반 워터마킹 기법 연구
장명환,황선태,이 형 대전대학교 산업기술연구소 2000 산업기술연구소 論文集 Vol.11 No.2
본 논문은 프랙탈의 반복함수계를 이용한 웨이블릿 기반의 워터마킹 기법을 제안한다. 제안한 방법에서는, 3-단계 웨이블릿 변환을 통하여 이미지를 주파수 대역으로 변환한다. 워터마크는 반복함수의 출력벡터의 수를 조절하여 생성한다. 견고성 향상을 위해 고주파수 대역뿐만 아니라, 저주파수 대역인 LL 대역에도 워터마크를 삽입한다. 또한, 워터마킹 영상의 화질저하를 줄이기 위해 웨이블릿 변환 단계마다 가중치를 다르게 부여한다. 실험결과, 기존의 Cox 방법과 비교할 때 잡음첨가, 부분 삭제 그리고 필터링등의 공격들에 대하여 화질과 견고성면에서 향상된 결과를 보였다. In this paper, the watermarking technique using the Iterated Function System based on wavelet transform is proposed. In this method, the image is chanced into coefficients of frequency domain by 3-level wavelet transform. We adjusted the number of Iterated Function Output Vectors and then generated watermarks. We intended to improve the robustness of the watermark by embedding the watermark not only into high-pass band(LH, HL, HH) but into low-pass band(LL). Also the scaling parameters are used differently in each wavelet transformation levels in order to reduce the distortion of watermarked image. The experimental results show that our proposed method has better image quality and robustness to the attacks of noise addition, cropping and filtering than those of existing Cox's method.
엘리베이터용 로프 브레이크 시스템의 설계변수 최적화에 관한 연구
윤영환,최명진,장승호 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.6
Hydraulic systems of rope brake for elevators are modelled to evaluate design parameters such as cylinder pressure, piston displacement, accumulator capacity, and so on. To assure the results, experiments were performed. The analysis results agree well with the experimental results. The scheme in this study is expected to be utilized in the design of rope brake system for elevators to get design parameters and to improve the safety.
김연희,장은혜,고명환,신승훈,양경혜,손진훈 한국뇌학회 2002 한국뇌학회지 Vol.2 No.2
본 연구는 fMRI를 사용하여 정서유발단어에 의한 주의이동과 관련한 뇌신경망을 규명하기 위하여 12명의 오른손잡이 여대생을 대상으로 수행하였다. fMRI 실험을 위한 뇌활성화 과제는 예비실험을 통하여 선정된 행복, 슬픔, 위협에 해당하는 각각 36개씩의 단어와 각 단어의 짝을 이루기 위한 중성단어를 이용하여 변형된 Posner 패러다임을 블록디자인으로 고안하였다. fMRI 영상은 1.5T Simens Vision scanner를 사용하여 실시하였으며, single-shot EPI 기법으로(TR/TE:3840/40ms, flip angle: 90, FOV: 220, 64x64 matrix, Slice thickness: 6mm) 이미지를 얻었고 피험자의 반응시간을 기록하였다. 자료분석은 SPM-99 소프트웨어를 사용하였다. 정서유발단어는 중성단어에 비하여 반응시간이 의미있게 빨라 효과적인 주의이동이 일어났음을 알 수 있었다. 정서유발단어와 중성단어에 의한 뇌활성화 상태를 감산분석한 결과, 좌측 상두정엽, 양측 후두엽 및 소뇌에서 뇌활성화를 보였고, 이들 영역은 정서유발단어에 의한 주의이동시 특징적으로 활성이 일어나는 뇌영역임을 보여주었다. 또한 여러 가지 정서가를 가진 단어에 의해 유발되는 주의의 정도가 특징적인 신경망의 활성과 관련되어 있음을 알 수 있었다. The purpose of this study is to delineate the neural network related to the shift of attention and its modulation by emotion-provoking words using functional MRI (fMRI). Twelve right-handed normal female volunteers participated in fMRI study. Their mean age was 24 years and the mean modified Edinburgh score was +90. Emotion-provoking words representing happy, sad, threatened, and neutral emotional valences respectively were chosen by the assessment of 60 normal volunteers using semantic differentiation and Mannequin scales. The activation tasks were designed using modified Posner's paradigm to have 4 blocks of each emotional and control periods, Imaging was conducted on a 1.5T Siemens Vision scanner. Single-shot echoplanar images (TR/TE = 3840/40 ms, flip angle = 90, FOV = 220, matrix = 62 ? 64, slice thickness = 6㎜) were acquired in 20 contiguous slices parallel to the AC_PC line as well as conventional T1-weighted images. Response times were obtained during the scanning, Imaging data were realigned, coregistered, normalized, smoothed, and statistically analyzed in group using SPM-99 software. The results showed that emotional valence of word stimuli produced the effect of attentional engagement. The left superior parietal, inferior frontal, bilateral occipital lobes and cerebellum were main area of modulation of attentional network by emotional words stimuli. The different extent of brain activation induced by different emotion-provoking words were determined.
백병준,유명상,신재민,김효진,박훈,김장묵,오천환 순천향의학연구소 2003 Journal of Soonchunhyang Medical Science Vol.9 No.2
Background and Objectives : Paranasal sinus cancer is rare when compared with cancers of other sites. Because paranasal sinus is anatomically located adjacent to the orbit and skull base, it is difficult to remove the tumor completely with tumor free margin in advanced paranasal sinus cancer. This report was conducted to investigate clinical characteristics, histologic type and treatment outcome of paranasal sinus cancer. Material and Methods : Twenty-six cases with paranasal sinus cancer diagnosed at the Department of otolaryngology-Head and Neck Surgery, Soonchunhyang Cheonan Hospital from January 1991 to September 2000 were studied by chart review, telephone interview and letters retrospectively. Results : The male to female ratio was 4.2 : 1. Most patients were 6th and 7th decade. The maxillary sinus was the most commonly affected site(61.5%), followed by the ethmoid sinus(34.6%). The most common histologic type of malignancy was squamous cell carcinoma(57.6%), followed by adenocarcinoma(19.2%). Most patients presented with T_(3)/T_(4) or locally advanced disease, N_(0)(91.3%), and M_(0)(100%) Sixtynine pertcent of this study group underwent sugery as part of a mutimodality curative treatment plan or alone as curative treatment. Eighteen patients(69.2%) developed recurrent disease at a median time of 278 days after initial treatment. Kaplan-Meier analysis revealed the 5-year disease specific survival was 34.6%. Conclusion : Most patients with paranasal sinus cancer presented with locally advanced disease. Adanced T stage was highly predictive of poor prognosis. Recurrence rate was high and mostly occured within the second year after treatment.
정전 열 접합을 이용한 Multi-Substrate Bonding
이덕중,주병권,최우범,한정인,조경익,이광배,장진,오명환 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1
We performed silicon-to-glass bonding using silicon direct bonding followed by anodic bonding(SDAB). Initial bonding between glass and silicon was caused by the hydrophilic surfaces of silicon and glass ensemble using silicon direct bonding(SDB) method. We found that the bonded specimen using SDAB process had higher strength than one using anodic bonding process only. We performed multiple layer bonding by SDAB, which is glass- silicon -glass as sandwich structure. In the silicon wafer, the (1mm x 2mm x 500μm)-sized cavity was formed by the anisotropic etching of the silicon substrate in EPW(Ethylendiamin-Pyrocatechol-Water). And, the cavity was sealed with glass wafers by SDAB method.
Jang, Hyosun,Myung, Hyunwook,Lee, Janet,Myung, Jae Kyung,Jang, Won-Suk,Lee, Sun-Joo,Bae, Chang-Hwan,Kim, Hyewon,Park, Sunhoo,Shim, Sehwan MDPI AG 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.1
<P>Radiation-induced skin injury can take the form of serious cutaneous damage and have specific characteristics. Asymptomatic periods are classified as the latent stage. The skin barrier plays a critical role in the modulation of skin permeability and hydration and protects the body against a harsh external environment. However, an analysis on skin barrier dysfunction against radiation exposure in the latent stage has not been conducted. Thus, we investigated whether the skin barrier is impaired by irradiation in the latent stage and aimed to identify the molecules involved in skin barrier dysfunction. We analyzed skin barrier function and its components in SKH1 mice that received 20 and 40 Gy local irradiation. Increased transepidermal water loss and skin pH were observed in the latent stage of the irradiated skin. Skin barrier components, such as structural proteins and lipid synthesis enzymes in keratinocyte, increased in the irradiated group. Interestingly, we noted sebaceous gland atrophy and increased serine protease and inflammatory cytokines in the irradiated skin during the latent period. This finding indicates that the main factor of skin barrier dysfunction in the latent stage of radiation-induced skin injury is sebaceous gland deficiency, which could be an intervention target for skin barrier impairment.</P>