Evaluation of the Clinical Performance by Using the Effective DQE for a Prototype Digital Breast Tomosynthesis System

최재구,김예슬,박혜숙,최영욱,함태희,김희중 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.5

Early experience with the application of tomosynthesis to breast imaging has shown the potential of digital breast tomosynthesis (DBT), which can improve the specificity of mammography with improved marginal visibility of the lesion and early breast cancer detection, especially for women with dense breasts. The purpose of this study is to characterize the physical properties of the DBT system and to optimize the exposure conditions by using the modulation transfer function (MTF), the noise power spectrum (NPS), the scatter fraction, the transmission fraction and the effective detective quantum efficiency (eDQE) for different breast thicknesses. The first-generation KERI prototype digital tomosynthesis system for breast imaging using a CMOS flat panel detector was used in this study. The spatial frequency depend on metrics depend on both the inherent properties of the detector and the imaging geometry including breast thickness. For a thicker breast, the eDQE decreases as the scatter fraction increases at a fixed tube voltage. Moreover, the MTF shows no significant difference with changing tube voltage while the eDQE at 27 kVp is slightly degraded. Consequently, the above critical properties of the DBT system for different exposure conditions and breast thicknesses should be fully considered before building the system and using it application in clinical applications.

『가장 푸른 눈』에 나타난 분열의 문제

최재구 경희대학교 비교문화연구소 1999 외대어문논총 Vol.9 No.-

효산 허종 교수 화갑기념 특집 : 듀 보이스의 이중의식과 창조적 수용

최재구 경희대학교 비교문화연구소 2004 비교문화연구 Vol.8 No.-

풍진동 제어를 위한 TMD의 제진성능에 대한 마찰계수의 영향

최재구,주석준,문종호,허석 한국풍공학회 2018 한국풍공학회지 Vol.22 No.1

본 연구에서는 마찰력에 따른 TMD의 작동-정지조건과 각 조건에 따른 운동방정식을 정리하고, TMD의 마찰계수가 풍진동 제어성능에 미치는 영향을 수치해석을 통하여 확인하였다. 일반적인 하중과 달리 풍하중은 크기와 방향의 변화가 크기 때문에 TMD는 마찰력에 의하여 작동-정지상태를 반복하게 되므로, TMD의 마찰계수를 주요 변수로 설정하였다. 또한 외부하중의 크기, 구조물의 진동수, TMD의 질량비도 매개변수로 설정하여 TMD의 제진성능에 대한 영향을 파악하고자 하였다. 자유진동, 조화강제진동, 풍진동에 대한 수치해석의 결과, 외부하중의 크기가 작고, 구조물의 진동수가 낮을수록 마찰계수에 의한 TMD의 제진성능의 손실이 커질 수 있음을 확인하였으며, 초고층 건물에 대한 TMD 설계시 마찰계수의 영향을 반드시 고려하여야 할 것으로 판단된다. This study summarized the operation and stopping conditions of TMD, equations of motion to each condition, and the control performance was confirmed by numerical analysis. Because wind load has a large change in size and direction, TMD repeats operation and stopping by wind-induced vibration, so friction coefficient was set as a main parameter. In addition, parameters such as the magnitude of the external load, the frequency of the structure, and the mass ratio of TMD were set to confirm the effect of control performance in TMD. As a result of numerical analysis, it was confirmed that loss of control performance of TMD due to friction coefficient is high when the external load is small and the structure frequency is low. The effect of friction coefficient should be considered when designing TMD for skyscraper buildings.

LCV를 이용한 대기환경 중 유해 자외선 측정에 대한 연구 : LCV의 이성질화 반응속도를 중심으로 Focusing on the lsomerization Reaction Rates of LCV

최재구,김종규 동남보건대학 2003 論文集-東南保健大學 Vol.21 No.2

The cis→trans thermal isomerization of LCV has been studied Sizable solvent effects on the rates for thermal isomerization of push-pull LCV's were observed. It is suggested that the isomerization proceeds via a rotational mechanism For non push-pull LCV, the lack of solvent effects on the rate of isomerization was observed. This suggests that the isomerization proceeds via an inversional mechanism for non push-pull LCV.

PSd-150 (3-cyclohexyl-methyl-amino-6-methyl-7-anilino-fluoran) 염료의 열 변색 현상에 관한 연구

崔載球,金鍾珪 동남보건대학 2002 論文集-東南保健大學 Vol.20 No.2

The thermochromism of PSD-150has been examined. The PSD-150 exists as a colorless lactone in aprotic solvents. However, the PSD-150 exists as the form of an equilibrium mixture of a colored zwitter-ion and a colorless lactone in protic solvents. When an acid is added to the solution, the PSD-150 exists as an equilibrium mixture a colorless lactone and a colored cation even in aprotic solvents. In order to understand the interaction between the PSD-150 and the solvent, absorption spectra of the PSD-150 in various solvents were measured. The systematic increase of the λ_(max) of the PSD-150 correlates with the hydrogen-bond donor ability of the solvent in neutral solution. The thermodynamic parameters of the PSD-150 have also been investigated. From the variation of absorbance with temperature, the standard enthalpy changes ΔH^0 of the equilibrium between the lactone and the zwitter-ion in various solvents have been determined. The standard enthalpy change ΔH^0 is approximately -7 kJ/㏖ in protic solvents. In acidic solution, the standard enthalpy change is measured to be to zero in protic solvents within the experimental error. When the carboxylic group is protonated in acidic solution, a poor interaction between the dye and the solvent is expected.

탄저균과 부루셀라균의 신속 검출법 개발

최재구,Choi, Jae-Gu 한국환경보건학회 2007 한국환경보건학회지 Vol.33 No.5

The livestocks are sometimes infected with pathogenic microorganisms such as bird influenza, brucellosis, pig cholerae, and salmonella. However, it is difficult to predict the outcome of these diseases because the livestocks are mostly raised in the rural areas. Efficient systems for detecting and alerting the onset of livestock diseases are urgently required. In these studies, the fluorescent analysis method, luminescent analysis method, and frequently used gene amplification method (polymerase chain reaction) have been developed in order to detect the pathogenic microbes in the early stages of disease progression. By using these developed systems, damages due to the livestock diseases induced by microbes can be minimized. If we can detect livestock diseases in the early stage, the costs for diagnosis and treatment will be reduced, and the livestock can be quickly recovered.

정맥유리피판술을 이용한 수부의 피부결손 재건

김용희,황종익,이동철,조성배,최재구 大韓成形外科學會 1995 Archives of Plastic Surgery Vol.22 No.4

Traumatic or thermal injury to the hand often leads to multidigital skin loss, exposing the tendons or joints. Therapeutic options for salvaging these digits include local, regional or distant flap transfer and free flap transplantation. In each case, however, there are significant drawbacks in clinical application to the sites of the injuries. In 1981 Nakayama suggested the feasibility of raising an arterialized venous flap based on an experimental study in an abdominal flap in rats. In 1984 Honda reported the first clinical application of the venous flap that recieved blood supply only through venous inflow and out-flow. We have experienced a series of 58 venous free flaps in the last 6 years. The results were as follows: The complete survival rate was 89% in the arterialized venous flap and 60% in the V-V Type(vein to vein anastomosis)venous flap.

서혜부 유리 피판술을 이용한 Romberg씨 질병의 치험

안덕균,김준범,최은정,강동구,최재구 건국대학교 의과학연구소 1993 건국의과학학술지 Vol.3 No.-

본 건국대학교 의과대학 성형외과학 교실에서 Romberg씨 질병으로 좌측의 안면 함몰을 주소로 내원한 여자 환자 1례에서 탈상피화시킨 서혜부 유리 피판술을 시행하여 좋은 결과를 얻었기에 이에 문헌 고찰과 함께 보고하는 바이다. Romberg's disease is progressive hemifacial atrophy, which begins before the age of 20-years, affecting the subcutaneous tissue and skin with later involvement of the muscle and osteocartilagenous frame work. The disease may be heralded by pigmentary changes of the hair, skin, or iris. When present, atrophy may originate from the cutaneous stigmata and may become so sharply delimited by the midline. There are a number of methods to correct the soft tissue deformity of the face. We had experienced 22-year old female patient who had a moderate soft tissue atrophy on the left side of the face. The patient was treated with a de-epithelized groin free flap. Superficial circumflex iliac vessels were used as donor pedicle and the superficial temporal vessels were recipient vessel. Initially moderate bulkiness was noted but after 6 months follow-up period the external contour was good and the patient satisfied. A case presentation and review of literatures are the basis of this report.

전산유체역학을 이용한 집진기의 유체유동 연구

崔載玖 동남보건대학 2001 論文集-東南保健大學 Vol.19 No.1

Computer has developed rapidly and used to calculate complicated fluid flow phenomena even to climate, airplane, environment, etc. Computational Fluid Dynamics(CFD) made it possible to research the experiments in science and engineering fields which can not be performed due to their expense, danger, or time. Recently it is prospected to accelerate the proliferation of CFD to various fields. In this study, Fluent code as a commercial code of CFD is used to scrutinize the fluid flow phenomena in a simple cyclone, a representative dust collector. A tangential entry cyclone in a standard size was gridded in 2D and 3D and calculated to iteration no. over 2800 by k-ε turbulence model in the conditions of = 1.2 (10℃) =1.76 10^-5 kg/m·sec (10℃), inlet = 1, U velocity = 24.384m/sec, turbulence intensity = 5%, and characteristic length = 80×10^-5kg/m·sec, in boundary conditions U velocity = 7.1m/sec, turbulence intensity = 5%, and characteristic length = 80×10^-3kg/m·sec. The results of this study were as follows: Mass flux in the cyclone was large in the near upper area between the outside cylinder and the inside cylinder under inlet, and getting smaller downward along the cone and upward to outlet in the middle of the cylinder. In the pressure distribution the pressure was highest at the upper and outer area between the outside cylinder and the inside. cylinder, the opposit side of the inlet, and getting lower downward along the inner wall of the cone and the outside cylinder and negative upward along the middle from the dust exit to outlet area.