관절염에서 NO의 역할

조소연,정춘식 덕성여자대학교 약학연구소 2005 藥學論文誌 Vol.16 No.1

레이저 경화면의 형상특징 해석을 위한 프랙탈 차원의 적용

옥철호,조연상,배춘익,박흥식,전태옥 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.2

The determination of surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of various frictional surface, the harding test was carried out under different experimental conditions in dry friction. And fractal descriptors was applied to frictional surface of laser modified steel with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Topography of frictional surface can be effectively obtained by fractal dimensions.

조직구성 수성망상증 2예

최연수,박일,죄희충,김원식,양태영,허경,안기완,정춘해 조선대학교 1993 The Medical Journal of Chosun University Vol.18 No.2

Histiocytic medullary reticulosis (HMR) is a malignant noeplastic process, with tumor cells belonging to the histiomonocytic line, and originally described by Scott and Robb-Smith in 1939 characterized by its acute onset, progression to death within a few months and its clinical features are fever, lymphadenopathy, hepatosplenomegaly, jaundice, and purpura common laboratory findings are characterized by severe anemia, leukopenia, thrombocytopenia and histologically by systemic progressive invasion of morphologically atypical histiocytes or of their precursor. 61 and 37-year-old males were admitted with camplaints of high fever and chilling sensation and were treated by cyclophosphamide, vincristine, prednison and antiobiotics, but patients all died 17 and 14 days after admission due to probably sepsis and respiratory failure.

Phase Error Reduction for Multi-frequency Fringe Projection Profilometry Using Adaptive Compensation

Choon Sik Cho,Junghee Han 한국광학회 2018 Current Optics and Photonics Vol.2 No.4

A new multi-frequency fringe projection method is proposed to reduce the nonlinear phase error in 3-D shape measurements using an adaptive compensation method. The phase error of the traditional fringe projection technique originates from various sources such as lens distortion, the nonlinear imaging system and a nonsinusoidal fringe pattern that can be very difficult to model. Inherent possibility of phase error appearing hinders one from accurate 3-D reconstruction. In this work, an adaptive compensation algorithm is introduced to reduce adaptively the phase error resulting from the fringe projection profilometry. Three different frequencies are used for generating the gratings of projector and conveyed to the four-step phase-shifting procedure to measure the objects of very discontinuous surfaces. The 3-D shape results show that this proposed technique succeeds in reconstructing the 3-D shape of any type of objects.

Dual- and Triple-Mode Branch-Line Ring Resonators and Harmonic Suppressed Half-Ring Resonators

Choon Sik Cho,Lee, J.W.,Jaeheung Kim IEEE 2006 IEEE transactions on microwave theory and techniqu Vol.54 No.11

<P>Ring resonators have been widely used for various applications. Dual-mode ring resonators have also been investigated due to their applicability to multifrequency mode requirement. In this paper, dual-mode ring resonators using a branch line are designed along with a systematic approach. Triple-mode branch-line ring resonators are also designed adding two branch lines to the ring resonator. Adding more branch lines, multimode resonators can be realized based on the design procedure developed here. The location of the branch lines determines the additional resonant frequencies other than the fundamental resonant frequency generated by the enclosing ring. Furthermore, half-ring resonators working at 2.5 GHz are proposed for suppressing multiple harmonics (second and third harmonics) and providing size reduction with employment of various physical configurations. Equalizing the even- and odd-mode phase delays, harmonics are suppressed effectively in the design of half-ring resonators. Double half-ring resonators with a long opening gap are investigated to continuously decrease the resonant frequency. An open-loop structure provides flexible design and lowers the resonant frequency. Two dual-mode ring resonators and one triple-mode ring resonator are simulated and fabricated along with three different half-ring resonators</P>

High-Isolation SPDT RF Switch Using Inductive Switching and Leakage Signal Cancellation

Choon Sik Cho,Byeong Wan Ha 한국전자파학회JEES 2014 Journal of Electromagnetic Engineering and Science Vol.14 No.4

A switch is one of the most useful circuits for controlling the path of signal transmission. It can be added to digital circuits to create a kind of gate-level device and it can also save information into memory. In RF subsystems, a switch is used in a different way than its general role in digital circuits. The most important characteristic to consider when designing an RF switch is keeping the isolation as high as possible while also keeping insertion loss as low as possible. For high isolation, we propose leakage signal cancellation and inductive switching for designing a singlepole double-throw (SPDT) RF switch. By using the proposed method, an isolation level of more than 23 dB can be achieved. Furthermore, the heterojunction bipolar transistor (HBT) process is used in the RF switch design to keep the insertion loss low. It is demonstrated that the proposed RF switch has an insertion loss of less than 2 dB. The RF switch operates from 1 to 8 GHz based on the 0.18-㎛ SiGe HBT process, taking up an area of 0.3 mm².

마이크로파 이미징 기반 뇌졸중 진단

조춘식(Choon Sik Cho) 한국전자파학회 2020 한국전자파학회논문지 Vol.31 No.2

뇌조직으로 흐르는 뇌혈류 이상으로 갑작스럽게 유발되는 국소 신경학적 결손 증상을 통칭하는 뇌졸중은 심장병과 암에 이어 세 번째로 큰 사망원인이며, 골든 타임이 매우 짧기 때문에 초기치료가 매우 중요하며, 접근 가능한 진단기기의 사용이 중요하다. 뇌졸중을 진단할 수 있는 주요 장비로는 CT와 MRI가 있으나, 가격 및 운영 상 지속적으로 검사하기가 어렵고 휴대가 불가능하다. CT는 전리 방사선을 사용하므로 환자에게 해로우며 이는 새로운 기기의 요구로 이어지고 있다. 마이크로파 기반 이미징 기술은 조직 간의 유전율 차이에서 발생하는 전자기파 산란 지도 작성에 기반하여 CT등을 대체할 의료 영상화 도구로 각광 받고 있다. 마이크로파 이미징은 생체 조직 전체의 조망, 저가격, 휴대 가능성 및 무 방사능 등의 장점을 지니고 있으므로 뇌의 혈액 흐름 이상을 진단하는 훌륭한 기술이 될 수 있고, 뇌졸중을 관리하는 훌륭한 영상화 도구로 사용할 수 있다. 우선 단층영상화기법이 두부 이미징(head imaging)에 적용되어 휴대 가능하고 상대적으로 저가인 영상화 기술로 발전해 오고 있다. 그리고 최근에는 표적에서 반사되어 돌아오는 반사파의 시간 지연을 이용하여 3차원 영상을 만들어내는 방법이 제안되어 홀로그래피 기법을 마이크로파 방식에 적용하기 시작하였으므로 마이크로파 이미징 기반 뇌졸중 진단은 향후 계속 진화하여 인류의 생명을 구하고, 삶의 질을 향상하는 데 많은 쓰임을 받을 것이다. Brain stroke, referred to as a local neurological deficit suddenly caused by abnormal blood flow to brain tissue, is the third leading cause of death after heart disease and cancer. Additionally, because of its very short golden hour, initial treatment and access to diagnostic devices are critical. The main equipment for diagnosing brain stroke are CT and MRI, but it is difficult to carry out continuous tests and the equipment are not portable. CT is detrimental to patients because it uses ionizing radiation, leading to the demand for new devices. Microwave-based imaging technology is emerging as a medical imaging tool to replace CT, based on the mapping of the electromagnetic scattering resulting from the difference in dielectric constant between tissues. Microwave imaging has the advantages of viability, low cost, portability, and radioactivity throughout a living tissue. Hence, it is an excellent technique for diagnosing blood flow abnormalities in the brain and a good imaging tool for managing brain stroke. In this study, tomography imaging has been applied to head imaging to develop portable and relatively inexpensive imaging technology. Further, a method for generating a 3-D image using the time delay of the reflected wave from the target has been proposed. With the application of the holography technique to the microwave method, the microwave imaging-based stroke diagnosis will continue to evolve, improving the quality of life.

주파수 다양 배열 레이다

조춘식(Choon Sik Cho) 한국전자파학회 2024 한국전자파학회논문지 Vol.35 No.2

위상 배열 레이다에서 동일한 방위각이 유지되고 있으면 거리 구분이 불가능하여 이를 해결하기 위한 한 방편으로 주파수 다양 배열 레이다가 제안되어 최근 많은 연구가 이루어지고 있다. 위상 배열 레이다가 위상이 다른 신호들을 배열하여 빔을 한 방위각으로 투사하는 레이다라면 주파수 다양 배열 레이다는 위상은 같으나 주파수가 다른 신호들을 배열하여 빔을 형성하는 레이다로써 거리와 방위각을 구분하는 2차원 빔을 형성하는 장점을 보인다. 주파수 다양 배열 레이다는 주파수 오프셋만큼 이웃하는 배열 요소들 사이 주파수를 소량 변경하여 표적으로 향하는 빔을 형성하는 방식을 사용한다. 이때 주파수 오프셋이 상수인지 변수인지, 또 선형적인지 비선형적인지에 따라서 빔 패턴의 형성이 변동된다. 위상 배열 레이다에 비하여 매우 뛰어난 장점이 존재하여 표적 탐지 정밀도에서 유리하나 여러 단점 또한 존재한다. 레이다의 성능을 발전시키고 단점을 극복하기 위한 다양한 연구성과들과 다양한 응용 현황을 본 고에서 고찰하여 주파수 다양 배열 레이다의 현재와 미래를 다루고자 한다. If the same azimuth angle is maintained in phased-array radar, it is impossible to distinguish the range. To solve this problem, frequency-diverse array radar has been proposed; many studies have been conducted recently. If the phased-array radar arranges signals with different phases and projects a beam at one azimuth angle, the frequency-diverse array radar produces a two-dimensional beam that distinguishes range and angle by arranging signals with the same phase but different frequencies. Frequency-diverse array radar produces a beam directed to a target by changing the frequency offset between neighboring array elements. The beam pattern varies according to whether the frequency offset is constant or variable, and whether it is linear or non-linear. Compared to phased-array radar, there are significant advantages including target-detection accuracy; there are also several disadvantages. In this paper, we discuss frequency-diverse array radar and its future, considering research achievements and applications to improve performance and overcome its disadvantages.

Co-contamination of Aflatoxins with Ochratoxin A and Zearalenone in Thuja orientalis Semen

Cho, So-Yean,Kang, Shin-Jung,Jung, Joo-Hee,Jeong, Byeong-Ok,Jeong, Choon-Sik Korean Society of ToxicologyKorea Environmental Mu 2009 Toxicological Research Vol.26 No.3

Korea is representative of a country that consumes herbal medicines; most of the herbal medicines circulating in South Korea have been imported from developing countries in Southeast Asia, such as China and Indonesia. Recently, domestic hygiene and safety are issues that have come to the forefront, because herbal medicines currently in circulation could possibly contain contaminants or residues. Furthermore, the appearance or discovery of harmful new species due to environmental and industrial developments is becoming a social problem. Therefore, it may be necessary to consider and investigate these matters on a continual basis. Recently, mycotoxin contaminations in such foods as cereals, nuts, and powdered red pepper have been reported. They have become a problematic issue; the possibility of contamination in herbal medicines has also been considered. Nevertheless, recognition of and research into mycotoxin contamination in herbal medicines has been scarce because herbal medicine is used in only a few nations. In this research, we identified contamination by aflatoxin which is known to be the most potent mutagenic, carcinogenic, and teratogenic mycotoxin in Thujae Semen, a herbal medicine. We also found co-contaminations involving other mycotoxins, including ochratoxin A and zeraleanone.

Optimized Switching Commutation SVPWM Control Algorithm for TSDPC Drive

Choon-Ho Cho,Chang-Yeong Choi,Geon-Sik Lee,Tae-Woong Kim,Jaeho Choi 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

The two-stage direct power converter has the following characteristics; bidirectional power flows, controllable input power factor, lower input harmonic current, no bulky DC-link circuit, requirements of many switches, and complexity of switching algorithm. SVPWM control scheme is not easier to be optimized because of control complexity. This paper proposes the optimized switching commutation SVPWM control algorithm which switching loss and THD of input/output powers are taken into consideration. The proposed algorithm can largely reduce switching loss and improve input/output power qualities by rearranging the space vector applied times. The effectiveness is verified through simulation analysis.