조혈모세포이식 환자에서 침습성 진균 감염에 대한 Micafungin의 예방 효과 및 안전성

김시현,이동건,최수미,권재철,박선희,최정현,유진홍,이성은,조병식,김유진,이석,김희제,민창기,조석구,김동욱,이종욱,민우성,박종원 대한감염학회 2010 감염과 화학요법 Vol.42 No.3

Background: Micafungin, a potent inhibitor of 1,3-β-D-glucan synthase, is a novel antifungal agent of the echinocandin class. In vitro study showed that micafungin was effective against Aspergillus species as well as Candida species, but clinical data on the prophylactic efficacy against invasive fungal infections (IFIs) other than candidiasis are still lacking. Materials and Methods: We identified 60 consecutive adult hematopoietic stem cell transplantation (HSCT) recipients who received at least 3 doses of micafungin during neutropenic period. Micafungin was started as an alternative in patients who were intolerant or had adverse events (AEs) to primary prophylactic antifungal agents. We retrospectively reviewed the medical records and analyzed the efficacy and safety of micafungin for prophylaxis against IFIs. Results: The patients either had autologous (n=9) or allogeneic (n=51: 1 syngeneic, 24 sibling, 26 unrelated donor) HSCT. Itraconazole oral solution (n=58) was the most frequently used first line antifungal agent for prophylaxis and was administered for median 11 days. The most frequent cause of switch to micafungin was vomiting (n=42). The duration of neutropenia and micafungin administration was median 13 and 12 days, respectively. A successful outcome was achieved in 45 (75%) patients. Empirical antifungal therapy was initiated in 13 (22%) patients. There were 2 cases (3.3%) of breakthrough fungal infections which comprised a probable invasive pulmonary aspergillosis and a possible invasive fungal sinusitis. There was no case of invasive candidiasis. A total of 53 (88%) patients experienced at least one AE regardless of causality during micafungin administration. The most frequent AEs were hypokalemia, vomiting, diarrhea, and elevated serum aspartate aminotransferase or alanine aminotransferase. Among the aforementioned AEs, only 1 case of diarrhea could be classified as a probable relation with micafungin when causality was assessed. There was no AEs that caused discontinuation of micafungin. Conclusions: Micafungin seems to be a safe and effective agent for prophylaxis of IFIs including aspergillosis as well as candidiasis in HSCT recipients. However, further large, prospective, and randomized comparative studies are warranted for aspergillosis.

신장이식 환자에서 HCMV 항원혈증 검사의 임상적 유용성

김탁,성흥섭,박관태,김송철,김성한,최상호,김양수,우준희,박수길,한덕종,이상오 대한감염학회 2009 감염과 화학요법 Vol.41 No.2

Background : This study was performed to determine the cut-off value and the predictability of symptomatic human cytomegalovirus (HCMV) infection according to the peak value of HCMV antigenemia assay in kidney transplant recipients. Materials and Methods : We reviewed the results of HCMV antigenemia assay (Chemicon, CA, USA) in patients who received kidney transplantation at our institution from May 2003 through May 2008, and investigated the existence and the type of HCMV infection by the medical record review. Patients who underwent the test only once during the episode or those who received ganciclovir for more than 48hrs before the test were excluded. The receiver-operator characteristic curve was drawn and the point showing maximum likelihood ratio (LR) was chosen as the cut-off value of symptomatic HCMV infection. Results : A total of 689 episodes were screened and 134 episodes were enrolled. Thirty-three (24.6%) episodes were symptomatic HCMV infection, 23 (17.2%) episodes were associated with HCMV syndrome, and 10 (7.5%) episodes were tissue-invasive diseases. The maximum LR was 7.5 (95% confidence interval, 4.014.2) and the cut-off value was 29.5 cells/200,000 WBC. The sensitivity, specificity, Positive predictive value, and negative predictive value were 66.7%, 91.1%, 71.0%, and 89.3%, respectively. Conclusions : The cut-off value of symptomatic HCMV infection by the peak value of HCMV antigenemia assay in our study was similar with previous results, although the sensitivity was relatively low.

랜덤 키 분할을 이용한 모바일 RFID 사용자의 프라이버시를 보호하는 상호 인증 프로토콜

정윤수(Yoon-Su Jeong),김용태(Yong-Tae Kim),박길철(Gil-Cheol Park),이상호(Sang-Ho Lee) 한국통신학회 2011 韓國通信學會論文誌 Vol.34 No.9

이동 통신망에 RFID 기술을 접목한 모바일 RFID는 사용자 자신이 휴대한 휴대전화로 제품에 부착된 RFID태그의 식별자를 읽고, 이 식별자를 이동통신망을 통해 네트워크로 전달하여 제품에 대한 정보를 얻는 기술이다. 그러나 모바일 RFID는 기존 RFID에서 요구되어지는 보안 요구사항 중 프라이버시 문제가 여전히 존재하는 문제점이 있다. 이 논문에서는 모바일 RFID 사용자가 태그 정보를 백 엔드 서버로부터 안전하게 전달받기 위해서 초기화 과정과 상호 인증과정에서 모바일 RFID 리더와 태그가 생성한 랜덤키를 임의의 크기로 분할하여 프라이버시 보호가 필요한 태그에 대해서 모바일 RFID 리더가 매 세션마다 난수생성기에 의해 항상 다른 하부키 값을 생성함으로써 태그의 어떤 정보도 제 3자에게 제공하지 않도록 하고 있다. 성능 평가 결과 제안 프로토콜은 등록 계산량과 로그인 계산량에서 모듈러 연산을 사용하는 기존 프로토콜과 달리 일방향 해쉬 함수를 사용하여 사용자의 정보를 등록하기 때문에 MARP 기법<SUP>[7]</SUP>과 Kim 등의 기법<SUP>[12]</SUP>보다 저장 공간과 계산량에서 효율성이 높았다. Mobile RFID which integrates mobile network with RFID technique is the technique to get the information of products by transmitting the identifier through mobile network after reading the identifier of RFID tag. It attached on the equipment as the mobile phone. However, mobile RFID has the privacy-related problem among requested secure problems required from the existing RFID. In this paper, the random key created by mobile RFID reader and Tag during the inter-certificating and initialization procedure for mobile RFID users to receive tag information from backend server securely is divided into random sizes and any information on the tag which requires the protection of privacy shouldn't be provided to anyone. In performance analysis, previous protocol used modulo operation in registration and login computation. But the proposed protocol has higher efficiency in saving space and computation volume than MARP scheme<SUP>[7]</SUP> and Kim. et. al<SUP>[12]</SUP> scheme because our protocol is accomplished by mutual authentication and registering user information through one-way hash function.

소아 신경심장성 실신환자에서 비정상적 심박수 프랙탈 상관에 대한 연구

김경용,주은영,염명걸,오재원,김창렬,김남수,이철범,노정일 대한소아과학회 2002 小兒科 Vol.45 No.9

산-염기 평형 장애 진단 전문가 시스템의 설계 및 구현

김기태,유석희,황수철 중앙대학교 기술과학연구소 1989 기술과학연구소 논문집 Vol.19 No.-

In this study, we designed and implemented a diagnostic system model to process the diagnosing problem of acid-base balance disorder by means of OPS5 and LISP which are a tool and a language, respectively for developing Al systems. The implemented knowledge base system consists of three kind of the knowldege : one analytic knowledge of blood test, two diagnostic knowledges obtained by etiologies and symptoms. The knowledge representation and the inference mechanism for diagnosis were implemented by OPS5, and all input / output was processed by a menu-driven method in support of the window functions of LISP.

최적의 회절 광학소자 설계를 위한 알고리듬 개발

김철수 경주대학교 정보전자기술연구소 2004 情報電子技術論叢 Vol.3 No.-

In this paper, we porposed an iterative hybrid algorithm for designing of optimal diffractive optical elements. To design an optimal diffractive optical element, genetic algorithm is used in the first searching process by block units, and the resulted diffractive optical element is used as an initial random pattern of simulated annealing algorithm. With the porposed algorithm, we designed binary and quaternary phase diffractive elements. and compared with the conventional iterative algorithm such as genetic algorithm and simulated annealing in terms of diffraction efficiency. Computer simulations shown that the proposed algorithm has better performance than the genetic and simulated annealing algorithm.

Image Watermarking using Fresnel-based Digital Holography and Interferometer

김철수 慶州大學校 2005 論文集 Vol.18 No.2

본 논문에서는 프레스넬 기반 디지털 홀로그라피와 마흐-젠더 간섭계를 이용하여 디지털 영상의 저작권을 보호할 수 있는 새로운 디지털 영상 워터마킹 방법을 제안한다. 먼저 워터마킹을 위해 이진 마크 영상의 프레스넬 디지털 홀로그램을 호스트 영상에 묻히는 워터마크 영상으로 사용하며, 이를 감쇄인자를 통해 호스트 영상에 중첩시킨다. 그리고 워터마크 영상을 추출하기 위해 워터마킹된 영상과 원 영상을 위상변조한 후, 두 영상의 간섭세기를 구하고, 이를 역 프레스넬 변환한다. 마지막으로 역변환된 정보를 디지털처리하여 워터마크 영상을 최종적으로 구한다. 제안된 방법의 타당성을 컴퓨터 시뮬레이션을 통해 확인하였다.

새로운 각도 다중화 방법을 이용한 홀로그래픽 광 메모리 시스템의 구현과 응용

김철수, 윤경식 김천대학교 1997 김천대학교 논문집 Vol.18 No.-

It is proposed that an holographic optical memory system for image storage in BaTiO3 crystal using new angular multiplexing method which controls the incident angle of reference beam electrically. In the new angular multiplexing method, the incident angle of the reference beam is controlled by using BPH(binary phase hologram), which is designed and optimized with SA(simulated annealing) algorithm and represented on LCTV(liquid crystal television) for real-time processing. The reference beam can be generated anywhere in two dimensional planes by Fourier transform of the BPH on the LCTV which is controlled by a computer. So, the vertical and horizontal incident angle of the reference beam on the BaTiO3 can be controlled simultaneously. Thus the proposedl holographic optical memory system is simple and stable because there is no mechanical movement in storage and reconstruction process of the images. By using the proposed system, we demonstrated storage and reconstruction experiments for four binary images. We also demonstrated an application experiment that can acquire large number of images than that of the stored images by controlling the number of reference beams. Through this experiment, the proposed holographic optical memory system is expected to be used in the realization of the weighted optical interconnections for optical computing and communications. 기준빔의 입사각도를 전기적으로 제어하는 새로운 각도 다중화 방법을 이용하여 BaTiO3에 영상을 저장히기 위한 홀로그래픽 광메모리 시스템을 제안하였다. 새로운 각도 다중화 방법에서, 기준빔의 입사각도는 SA 알고리듬으로 설계되고 최적화된 BPH를 이용하여 제어하며, 실시간 처리를 위해 LCTV에 표현한다. 기준빔은 컴퓨터에 의해 제어되는 LCTV위의 BPH를 푸리에 변화하므로써 이차원 평면 어느곳에서나 생성할 수 있어 BaTiO3에 입사되는 기준빔의 수직측 및 수평측 입사각도를 동시에 제어할 수 있다. 그러므로 제안된 홀로그래픽 광메모리시스템은 영상의 저장과 재생과정에서 기계적인 움직임이 없기 때문에 간단하고 안정한다. 제안된 시스템을 이용하여 네개의 이진 영상을저장하고 재생하는 광실험을 하였다. 또한 저장된 영상의 수보다 더 많은 수의 영상을 기준빔의 수를 제어하여 얻을 수 있는 응용실험도 하였다. 이 설험을 통하여 제안된 홀로그래픽 광메모리 시스템은 광컴퓨팅 및 통신에서 가중치 광연결을 실현하는데 이용될 것으로 기대된다.

시각 암호화와 가상 위상 영상을 이용한 광학적 보안 시스템

김철수 경주대학교 2003 論文集 Vol.16 No.-

In this paper, we proposed an optical security system using visual cryptography and virtual phase images. In encryption process, original image is shared out virtual image, random iamge, and decryption key image, and they are phase modulated. We multiply the phase virtual image with the phase random image, and then multiply with each complex image which has its magnitude with constant value. Finally, the encryption cards are made by Fourier transforming the multiplicated images. It is possible to protect information of the orignal image because the cards have not any information of the original image. To reconstruct the original image from the encrypted card images, Encrypted card images are put on the paths of Mach-Zehnder interferometer to be summed the card images. The summed image is inverse Fourier transformed by Fourier lens, and multiplied with phase decryption key and then interferenced with reference beam again. Finally, the original image is recovered in the form of intensity on the CCD plane. Computer simulations show a good performance of the proposed optical security system.

인공 석회화 기질의 개발 및 파골세포에 의한 기질흡수에 관한 연구

김현만,박주철,임도선,박수진,김윤지,고재승 대한구강해부학회 1997 대한구강해부학회지 Vol.21 No.1

To develop artificial matrix resorbable by osteoclasts can be used as a model system that biological function of osteoclasts would be assayed in vitro in a standardized condition instead of using heterogenous bone or dentin slices. The present study developed artificial substrates consisted of apatite crystals. collagen gen. agar, apatite crystals under collagen film, mixture of apatite crystals and collagen, and mixture of agar and apatite crystals. And osteoclastic attachement and resorption activity on the each substrate was assayed in vitro. Osteoclasts attached to apatite crystals, collagen, mixture of apatite crystals and collagen, and mixture of apatite crystals and agar, however, not to agar. This suggested that apatite crystals and collagen should be exposed on the surface of artificial substrate where osteoclasts can attach. Osteoclasts attached to the substrate resorbed the substrate consisted of apatite crystals, mixture of apatite crysals and collagen, and apatite crystals under thin film of collagen, however, not of collagen, mixture of apatite crystals and agar. This suggested that the first phase of osteoclasts in resorbing matrix is to secrete acid and the end result of this phase, whatever it may be, may activate secretion of hydrolytic enzymes specific to organic components.