슬관절 치환술을 받는 노인 환자에서 지혈대에 의한 허혈-재관류 손상 시 Vitamin C 투여가 혈역학적 변화와 동맥혈 가스에 미치는 영향

김창재 대한마취통증의학회 2008 Anesthesia and pain medicine Vol.3 No.4

Background: Free radicals, such as reactive oxygen species which are released abruptly after deflation of an ischemic tourniquet, cause reperfusion injuries. Vitamin C produce cytoprotective effects due to reduction of free radicals. This study was designed to investigate the effect of vitamin C on hemodynamics and arterial blood gas during unilateral total knee replacement. Methods: In the vitamin C group (VC group: N = 19), patients were administrated with vitamin C:a priming bolus of vitamin C 0.06 g/kg mixed with 100 ml saline infused for 20 min at 10 min before deflation of tourniquet, followed by vitamin C 0.02 g/kg mixed with 30 ml saline at 0.5 ml/min. In the control group (control group: N = 15), patients were infused by 100 ml saline. Mean arterial blood pressure, heart rate and arterial blood gas were measured at 20 min after anesthesia induction, just before deflation, 5 min after deflation and 20 min after deflation of tourniquet. Results: Mean arterial blood pressure in the VC group was maintained higher than control group at 1 min after deflation of the tourniquet. Arterial O2 tension and saturation in the VC group were higher than control group at 5 min and 20 min after deflation of the tourniquet. Conclusions: We concluded that the administration of vitamin C during total knee replacement could inhibit decline of mean arterial blood pressure and arterial oxygenation induced by ischemiareperfusion significantly.

서비스기반의 소프트웨어 유지보수 성숙도 모델

김창재,박제원 한국정보기술학회 2014 한국정보기술학회논문지 Vol. No.

Let's current software maintenance concept of service-oriented paradigm has evolved according to the characteristics of software maintenance processes and maturity models for quantitative performance measures need to be developed. According to the attributes of software maintenance and development and maintenance of a maturity model fits improve guidance characteristics developed and applied . In order to provide high quality maintenance services, follow presented guidelines and project characteristics, the research about selection process is necessary. In this study, 34 software maintenance projects at institute K are the target of research. We perform the survey, and according to projects’ characteristics, process area and procedures for developing indicators are presented. Software Maintenance Maturity Model is developed through detailed indicators to assess achievement of indicators, maintenance is being performed to determine the level of maturity. It could be used as guidelines for the improvement. 최근 소프트웨어 유지보수가 하자 유지보수 개념에서 서비스 중심의 유지보수로 패러다임이 변화함에 따라 소프트웨어 유지보수 특성에 따른 프로세스 및 정량적인 성과측정을 위한 성숙도 모델 개발이 필요하다. 소프트웨어 유지보수 특성에 따른 성숙도 모델을 개발하고 유지보수 특성에 맞는 개선지침을 개발하여 적용․평가․개선의 환류체계를 통해 소프트웨어 유지보수의 품질을 향상 할 수 있다. 본 연구에서는 안전행정부 산하 기관인 K원에서 수행하고 있는 34개의 소프트웨어 유지보수 사업을 대상으로 설문조사를 수행하여 프로젝트 특성에 따른 프로세스 영역 및 지표를 개발하는 절차를 제시한다. 개발된 소프트웨어 유지보수 성숙도 모델은 세부지표를 통한 지표달성을 평가하여 수행중인 유지보수 성숙도 수준을 판단하여 이를 개선하기 위한 지침으로 활용할 수 있다.

Effect of Prior Probabilities on the Classification Accuracy under the Condition of Poor Separability

김창재,어양담,이병길 한국측량학회 2008 한국측량학회지 Vol.26 No.4

This paper shows that the use of prior probabilities of the involved classes improve the accuracy of classification in case of poor separability between classes. Three cases of experiments are designed with two LiDAR datasets while considering three different classes (building, tree, and flat grass area). Moreover, random sampling method with human interpretation is used to achieve the approximate prior probabilities in this research. Based on the experimental results, Bayesian classification with the appropriate prior probability makes the improved classification results comparing with the case of non-prior probability when the ratio of prior probability of one class to that of the other is significantly different to 1.0.

Comparison of various tests designed to assess the recovery of cognitive and psychomotor function after ambulatory anesthesia

김창재,홍상현,김병삼,천준표,이윤기,고현정,이재민 대한마취통증의학회 2008 Korean Journal of Anesthesiology Vol.53 No.3

Background: Few studies have been conducted to evaluate the reliability of the various tools used to assess cognitive and psychomotor recovery after ambulatory anesthesia. Therefore, this study was conducted to compare the sensitivity and reliability of simple, standard tests used to measure postoperative cognitive and psychomotor functions. Methods: Twenty-seven patients admitted for same day surgery were included in this prospective, randomized study. While in the preanesthetic unit, each patient was asked to perform three different standard psychometric tests, the digit symbol substitution test (DSST), digit span test (DST), and perceptual speed test (PST), to evaluate cognitive and psychomotor functions. The results were then used as baseline values that were subsequently compared to results obtained when patients repeated the tests at 15, 30 and 60 min after extubation. In addition, the observer’s assessment of alertness and sedation was evaluated. Results: The DSST scores were significantly lower than the baseline scores at 15 and 30 min after extubation, with a performance ratio of 64.9 and 89.2, respectively (P < 0.05). The DST scores had returned to preanesthetic levels at 30 min post-anesthesia and the PST scores were found to be significantly higher than the baseline scores at 30 and 60 min post-anesthesia. Conclusions: DSST is a more sensitive indicator of residual drug effect following anesthesia than the other tests evaluated in this study. In addition, a learning effect was obvious when the PST was administered. Background: Few studies have been conducted to evaluate the reliability of the various tools used to assess cognitive and psychomotor recovery after ambulatory anesthesia. Therefore, this study was conducted to compare the sensitivity and reliability of simple, standard tests used to measure postoperative cognitive and psychomotor functions. Methods: Twenty-seven patients admitted for same day surgery were included in this prospective, randomized study. While in the preanesthetic unit, each patient was asked to perform three different standard psychometric tests, the digit symbol substitution test (DSST), digit span test (DST), and perceptual speed test (PST), to evaluate cognitive and psychomotor functions. The results were then used as baseline values that were subsequently compared to results obtained when patients repeated the tests at 15, 30 and 60 min after extubation. In addition, the observer’s assessment of alertness and sedation was evaluated. Results: The DSST scores were significantly lower than the baseline scores at 15 and 30 min after extubation, with a performance ratio of 64.9 and 89.2, respectively (P < 0.05). The DST scores had returned to preanesthetic levels at 30 min post-anesthesia and the PST scores were found to be significantly higher than the baseline scores at 30 and 60 min post-anesthesia. Conclusions: DSST is a more sensitive indicator of residual drug effect following anesthesia than the other tests evaluated in this study. In addition, a learning effect was obvious when the PST was administered.

Microstructure and Mechanical Properties of Ni–Cr–Y2O3 Alloy Sintered Powder Composed of Oxide-Embedded Metallic Particles

김창재,곽정호,임재원,오민석,박제신 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.12

In this study, oxide (Y2O3)-embedded Ni particles were fabricated via a new process. The process involves the mechanical hydrogenation of Ni–Y alloy into Ni–YH2 and the selective oxidation of Ni–YH2 to Ni–Y2O3. The alloy powders were prepared for sintering by the mechanical alloying of a mixed powder. The powder was prepared with a desired composition (Ni–20wt.%Cr–1.2wt.%Y2O3) by adding Ni and Cr powders to the Ni–Y2O3 composite prepared by the new process. For comparison, a mixed powder with the same composite was prepared using a conventional mechanical alloying (MA) approach. Samples of the two powders were sintered by SPS at 850, 900, 950, and 1,000 oC. The relative densities of all samples were higher than 99.7% at all sintering temperatures. The oxide particles and matrix grain sizes of the Ni–20Cr–1.2Y2O3 alloy prepared by this new process were finer than those in alloys fabricated by conventional MA processes. Therefore, the improvement in the mechanical properties of the Ni–20Cr–1.2Y2O3 alloy prepared by the new process was attributed to the refinement of the oxide particles.

초점거리 편의가 지상 정확도에 미치는 영향 비교 연구 - 세가지 라인 스캐너를 대상으로 -

김창재 한국측량학회 2014 한국측량학회지 Vol.32 No.4

Most space-borne optical scanning systems adopt linear arrayconfigurations. The well-knownthree differenttypes of space-borne sensors arealong-track line scanner, across-track linescanner, and three line scanner. Toacquire accurate location information of an object on the ground withthose sensors, the exterior and interiororientation parameters are critical factors for both of space-borne and airborne missions. Since the imaginggeometry of sensors mightchange time to time due to thermal influence, vibration, and wind, it is very importantto analyze the Interior Orientation Parameters (IOP) effects on the ground. The experiments based on syntheticdatasets arecarried out while the focal length biases are changing. Also, both high and low altitudes of theimagingsensor were applied. In case with the along-track line scanner, the focal length bias caused errors alongthe scanline direction. In the other case with the across-track one, the focal length bias caused errors alongthescan line and vertical directions. Lastly, vertical errors were observed in the case ofthree-line scanner. Thoseresults from this study will be able to provide the guideline for developing new linearsensors, so as for improvingthe accuracy of laboratory or in-flight sensor calibrations. 다수의광학위성센서들이선형 배열 형태에 기반을두고설계되었다. 널리알려진광학위성센서의종류는다음과같이경로평행방향1열스캐너(along-track line scanner), 경로직각방향1열스캐너(across-track linescanner), 3열스캐너(three- line scanner)로구분할수있다. 이들센서들을이용하여 위성 및 항공기에서지상지물의정확한위치정보를획득하려고할때센서의외부표정요소와내부표정요소는매우중요한요소들이다. 이들센서들의 영상생성기하구조는 태양에 의한열영향, 진동, 바람등의다양한물리적현상들에의하여시시각각변동될가능성이 있기에 내부표정요소의 편의가지상에미치는영향을분석하는것은매우중요하다. 실제적인비행경로와자세정보를바탕으로생성된 시뮬레이션 자료를 이용하여 본 연구에서는 각센서의초점거리에편의량을점진적으로추가하면서실험과 분석을 수행하였으며,또한비행고도를고고도와저고도의두가지경우로비교하였다.실험결과, 경로평행방향1열스캐너의경우에초점거리편의량의증가가지상스캔라인방향(Y 방향)의오차를유발하였으며, 경로직각방향1열스캐너의경우스캔라인방향과 수직방향으로오차가증가하였고, 3열스캐너의경우에는수직방향으로만오차가증가하였다. 이들실험결과는향후새로운센서개발과센서캘리브레이션정확도에가이드라인을제공할수있다고본다.

극한지 탐사 로버의 카메라 시스템 설계를 위한 시뮬레이션 기법 개발

김창재,박재민,최원석,신휴성,홍성철 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.12

In extreme environment regions, unmanned rovers equipped with various sensors and devices are being developed for long-term exploration on behalf of humans. On the other hand, due to the harsh weather conditions and rough terrain, the rover camera has limited visible distance and field of view. Therefore, the rover cameras should be located for safe navigation and efficient terrain mapping. In this regard, to minimize the cost and time to manufacture the camera system on a rover, the simulation method using the rover design is presented to optimize the camera locations on the rover efficiently. In the simulation, a simulated terrain was taken from cameras with different locations and angles. The visible distance and overlapped extent of camera images, and terrain data accuracy calculated from the simulation were compared to determine the optimal locations of the rover's cameras. The simulated results will be used to manufacture a rover and camera system. In addition, self and system calibrations will be conducted to calculate the accurate position of the camera system on the rover. 극한환경 지역에서 무인 로버는 다수의 센서와 장비를 탑재하고 인간을 대신해 장기간 탐사 임무를 수행하기 위해 개발된다. 하지만 혹독한 기상과 거친 지형조건을 가진 극한환경 지역에서 로버 카메라 영상은 제한된 가시거리와 시야각을 가지므로, 카메라들은 안전한 원격 주행과 효율적 지형정보 구축을 위해 배치되어야 한다. 이에 본 연구에서는 로버 설계 도면을 기반으로 한 카메라 배치 시뮬레이션을 수행함으로써, 향후 로버 카메라 시스템 제작을 위한 시간과 비용을 최소화 하고자 하였다. 제안한 로버의 카메라 시스템은 총 8대의 카메라가 탑재되며, 기능적 요건에 따라 탐사 및 주행 카메라로 분류 된다. 카메라 배치 시뮬레이션에서는 카메라들의 위치와 경사 각도를 변경하여 가상의 지형을 촬영한다. 로버 카메라의 최적 배치는 가상 지형영상의 가시거리 및 중첩도, 지형 데이터의 정확도 등을 비교 및 분석하여 결정하였다. 카메라 배치 시뮬레이션 결과는 실제 로버 제작에 반영될 예정으로, 향후 극한환경지역을 모사한 모의 지형을 구축하고 로버 성능을 종합적으로 평가하여 로버 카메라 시스템의 성능을 개선할 예정이다.

구연 : 그랜드볼룸 ; 간세포암종에서 FEN1 유전자의 변이 (초)

김창재,박보령,정석원,신정우,박능화 대한간학회 2010 Clinical and Molecular Hepatology(대한간학회지) Vol.16 No.3(S)

MAD1 우전자의 단염기다형성이 B형간염바이러스 관련 간세포암종의 발생에 미치는 영향

김창재,박능화,신정우,박보령,정석원,이세환,이단비,김성은,김정아,정영화 대한간학회 2008 Clinical and Molecular Hepatology(대한간학회지) Vol.14 No.3(S)

한국인 위암에서 Caspase 2 단백 발현 양상

김창재 대한위암학회 2003 Journal of gastric cancer Vol.3 No.1