• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.274-281
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• 2016

Background: Whole-body counters are widely used to evaluate internal contamination of the internal presence of gamma-emitting radionuclides. In internal dosimetry, it is a basic requirement that quality control procedures be applied to verify the reliability of the measured results. The implementation of intercomparison programs plays an important role in quality control, and the accuracy of the calibration and the reliability of the results should be verified through intercomparison. In this study, we evaluated the reliability of 2 whole-body counting systems using 2 calibration methods. Materials and Methods: In this study, 2 whole-body counters were calibrated using a reference male bottle manikin absorption (BOMAB) phantom and a Radiation Management Corporation (RMC-II) phantom. The reliability of the whole-body counting systems was evaluated by performing an intercomparison with International Atomic Energy Agencyto assess counting efficiency according to the type of the phantom. Results and Discussion: In the analysis of counting efficiency using the BOMAB phantom, the performance criteria of the counters were satisfied. The relative bias of activity for all radionuclides was -0.16 to 0.01 in the Fastscan and -0.01 to 0.03 in the Accuscan. However, when counting efficiency was analyzed using the RMC- II phantom, the relative bias of $^{241}Am$ activity was -0.49 in the Fastscan and 0.55 in the Accuscan, indicating that its performance criteria was not satisfactory. Conclusion: The intercomparison process demonstrated the reliability of whole-body counting systems calibrated with a BOMAB phantom. However, when the RMC-II phantom was used, the accuracy of measurements decreased for low-energy nuclides. Therefore, it appears that the RMC-II phantom should only be used for efficiency calibration for high-energy nuclides. Moreover, a novel phantom capable of matching the efficiency of the BOMAB phantom in low-energy nuclides should be developed.

• 대한안전경영과학회지
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• 제17권3호
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• pp.133-141
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• 2015

This study tried to identify the problems associated with the posture to be analyzed and tried to suggest guidelines for MSDs(Musculoskeletal Disorders) evaluation based on working posture. A total of 50 jobs from 3 different types of industries(electronics, hospitals, automobiles) were used for MSDs evaluation study which was done by 6 observers. Two indexes were applied to identify the problem in this study which were percentage of agreement and counter-time-error rate. Specifically, 'counter-time-error rate' represented a degree of consistency in terms of selecting the posture to be analyzed time after time. Main results of the study were as follows; 1) The average percentage of agreement for representative posture for whole body was relatively higher than that for representative postures for individual body parts, 2) The counter-time-error rate(%) has been reduced as the evaluation process has repeated for the same job. 3) The counter-time-error rate(%) for electronics, hospitals, and automobiles were 63.4%, 61.2%, and 67.3% respectively. 4) The counter-time-error rate(%) for the job with the work cycle of 0.5 to 2 minutes were lower than that of the jobs with the work cycles less than 0.5 minute or greater than 2 minute. 5) The work cycles and the number of trials had significant effects on counter-time-error rate while the types of industries did not have significant effects on counter-time-error rate. Some guidelines could be prepared from the results of the study. Probably, there should have an extension in terms of form and matter for this study in order to have more practical output.

• Journal of Radiation Protection and Research
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• 제34권1호
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• pp.37-42
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• 2009

국내 원전에서는 원전종사자의 내부피폭 방사능을 측정하기위해 전신계측기를 이용하고 있다. 이 전신계측기는 Sodium Iodide를 이용한 섬광검출기로서 짧은 시간에 종사자가 보유한 방사성핵종과 방사능을 측정하는 기능을 가지고 있다. 그런데 종사자의 신체표면에 부착된 오염과 내부에 침적된 오염을 구분하지 못하기 때문에 방사선계측 과정에서 종종 오류를 범할 가능성이 있으며, 이 경우 내부피폭선량은 매우 보수적으로 과대평가된다. 이러한 문제점을 개선하고자 종사자의 인체 내부와 외부 표면오염을 구분하고, 보다 체계적으로 오염부위를 확인할 수 있도록 전신계측기와 인체모형 팬텀을 이용한 방사능 계측실험을 수행하였다. 또한 원전에서 발생하는 주요 핵종의 신체내 침적위치를 고려하여 전신계측기의 최적 방사능 측정모드를 결정하는 실험을 수행하였다. 이러한 방사능 측정 실험결과를 근거로 원전종사자의 내부방사능 측정과 선량평가 절차를 개선하였다. 이에따라 보다 정확한 전신계측프로그램의 적용으로 내부피폭선량의 보수적 평가를 방지할 수 있을 것으로 기대된다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.579-583
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• 2003

본 연구는 원자력발전소에서 방사선작업에 따른 I-131 흡입후 전신선량계측(Whole Body Counter WBC)한 결과에 따라 각 내부피폭 선량평가 코드를 이용하여 섭취량과 예탁유효선량(CED : Committed Effective Dose)을 계산하였다. 여기에는 국내에서 개발된 KIDAC 코드, 일본의 MONDAL 코드, 영국의 LUDEP 코드와 IMBA 코드가 이용되었다.

• 제어로봇시스템학회논문지
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• 제19권3호
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• pp.233-239
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• 2013

This paper presents the analysis and control of the position of the COG (Center of Gravity) for a two-wheel balancing robot. The two-wheel balancing robot is required to maintain balance by driving two wheels only. Since the robot is not exactly symmetrical and its dynamics is changing with respect to moving parts, robust balancing control is difficult. Balancing performance becomes difficult when two arms hold a heavy object since the center of gravity is shifted out of the wheel axis. Novel design of a sliding waist mechanism allows the robot to react against the shift of the COG by moving the whole upper body to compensate for the imbalance of the mass as a counter balancer. To relocate the COG position accurately, the COG is analyzed by force data measured from two force sensors. Then the sliding COG mechanism is utilized to control the sliding waist position. Experimental studies are conducted to confirm the proposed design and method.

• 한국운동역학회지
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• 제17권2호
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• pp.167-176
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• 2007

The purpose of this study was to offer suitable model for performing Tippelt motion and data for training Tippelt motion through the quantitative kinematical analysis of Tippelt motion in parallel bars. The results of analysing kinematic variations through three-dimensional reflection analysis of three members of the national team as the objects of the study were shown as follows. 1. It seemed that the shoulder-joints which are stretched as much as possible affects the whole Tippelt motion while one is swinging downward. The time of process of the center of mass for the body reaching to the maximum flection point should be quick and body's moving from the vertical phase to the front direction should be controled as much as possible. 2. While one is swinging upward, the stability of flying motion could be made certain by the control of body's rapid moving to the front direction and stretching shoulder-joints and hip-joint to reverse direction. 3. While one is flying upward, the body should be erected quickly and lessening the angle of the hip-joint affects the elevation of flight. When the powerful counter turn motion is performed, the stable motion could be made. As a result of this study, It seems that sudden fall and the maximum stretch of shoulder-joints is important during performing Tippelt motion in parallel bars. Also, it concludes that the maximum bending of hip-joints at the starting point of upward swing, sudden stretch to the reverse direction of shoulder-joints and hip-joints when one is leaving bars, control of body's moving to the front direction, and lessening the angle of hip-joints at the flying phase is important.

• Journal of Advanced Marine Engineering and Technology
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• 제39권10호
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• pp.1023-1030
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• 2015

The purpose of this paper is to present the basic mathematical modeling of a hexacopter, which could be used to develop proper methods for stabilization and trajectory control. A hexacopter consists of six rotors with three pairs of counter-rotating fixed-pitch blades. This mechanism is an under-actuated, dynamically unstable, six-degrees-of-freedom system. The whole motion of this object consists of translational and rotational motion in three dimensions, where the translational motion is created by changing the direction and magnitude of the upward propeller thrust. The hexacopter is controlled by adjusting the angular velocities of the rotors, which are spun by electric motors. It is assumed to be a rigid body; thus, the differential equation of the hexacopter dynamics can be derived from the Newton-Euler equation. The Euler-angle parametrization of the three-dimensional rotations contains singular points in the coordinate space that can cause failure of both the dynamical model and control. In order to avoid singularities, the rotations of the hexacopter are parametrized in terms of quaternions. This choice has been made considering the linearity of the quaternion formulation and their stability and efficiency. Further, control simulation of a hexacopter applying cascaded-PID control is also presented in this paper.

• Radiation Oncology Journal
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• 제15권3호
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• pp.197-206
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• 1997

목적 : Phospholipase D (PLD)는 phosphatidylcholine을 phosphatidic acid (PA)와 choline으로 가수분해 시키는 효소이다. 최근 이 효소는 다른 phospholipase들과 유사하게 세포 신호전달과정에 관여하는 것으로 알려져 많은 관심의 대상이 되고 있으며, 아울러 발암과정에 관여하리라는 추측을 하게 하고 있다. 이 실험에서는 쥐를 방사선 조사하여 각 조직에서 올레산-PLO에 미치는 영향을 관찰하였다. 방법 : PLD assay를 위한 반응 혼합물에는 $0.1\;\muCi$의 $1,2-di[1^{14}C]palmitoyl$ phosphatidylcholine, 0.5mM phosphatidylcholine, 5mM sodium oleate, $0.2\%$ taurodeoxycholate, 50mM HEPES buffer(pH 6.5), 10mM $CaCl_2$와 25mM KF 를 함께 넣어주었다. 생성된 PA는 TLC로 분리하여 그 방사능을 측정하였다. 사용된 동물은 암컷 Wistar 쥐로서 코발트 60 원격치료 기기를 이용, 조사범위를 $10cm\times10cm$로하여 분당 선량율 2.7Gy로 방사선 조사선랸 l0Gy와 25Gy를 조사 하였다. 결과 : PLD 활성은 폐조직에서 가장 높았으며 신장, 근육, 리, 비장, 골수, 흥선. 간의 순으로 나타났다. 방사선 조사결과 PLD 활성에 변동을 보인 조직은 흥선, 비장, 폐와 골수이며, 특히 흉선과 비장은 PLD의 할성이 각각 2배 이상 증가한 것으로 관찰되었다. 이와는 반대고 골수의 PLD는 $30\%$ 이상 감소한 것으로 나타났다. 한편 PLD 활성값이 가장 낮은 판은 방사선 영향을 거의 받지 않는 것처럼 보였다. 결론 : 동물전신에 방사선 조사시 PLD가 가장 민감한 영향을 받는 조직은 림프양 기관과 조혈 세포인 것으로 보여 PLD가 이들 조직의 생리기능과 밀접한 관계가 있음을 암시해 주고있다. 더 나아가 방사선 긴장 (radiation stress)이 이들 조직의 세포증식내지 괴사현상연구에 중요한 수단을 제공해 줄 수 있을 것이다.

• Journal of Radiation Protection and Research
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• 제15권2호
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• pp.17-25
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• 1990

백서의 장기 내 카드뮴의 축적분포를 중성자 조사에 의한 방사분석법으로 조사하였다. $CdCl_2$를 1주일에 10mg/kg씩 급식되도록 매일 물병으로 투여하였으며 1주, 2주, 3주, 1개월, 2개월 및 3개월 기간동안 장기 복용케한 후 주요장기 및 체모를 시료로 하여 방사화 분석을 수행하여 아래와 같은 결론을 얻었다. 1) $^{115m}Cd$을 방사추적자로 사용하여 24시간 경과 후 체내 카드뮴의 분포를 조사한 결과 혈액에 0.03% 신장에 2.99% 간장에 3.50%를 나타내었다. 2) Cd은 혈액을 통해 신속히 순환되어 신장을 통하여 배설되나 간장과 체모에도 축적되는 결과를 나타냈다. 3) $CdCl_2$를 급식케 한 실험군의 주요 장기별 Cd함량을 측정 비교한 결과를 이용하여 간장 내 Cd의 축적을 체모 내 Cd함량으로부터 진단하는 지표로 사용이 가능케 되었다.

• Advances in nano research
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• 제14권5호
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• pp.435-442
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• 2023

Sports activities, including playing tennis, are popular with many people. As this industry has become more professionalized, investors and those involved in sports are sure to pay attention to any tool that improves athletes' performance Tennis requires perfect coordination between hands, eyes, and the whole body. Consequently, to perform long-term sports, athletes must have enough muscle strength, flexibility, and endurance. Tennis rackets with new frames were manufactured because tennis players' performance depends on their rackets. These rackets are distinguished by their lighter weight. Composite rackets are available in many types, most of which are made from the latest composite materials. During physical exercise with a tennis racket, nanocomposite materials have a significant effect on reducing injuries. Materials as strong as graphite and thermoplastic can be used to produce these composites that include both fiber and filament. Polyamide is a thermoplastic typically used in composites as a matrix. In today's manufacturing process, materials are made more flexible, structurally more vital, and lighter. This paper discusses the production, testing, and structural analysis of a new polyamide/Multi-walled carbon nanotube nanocomposite. This polyamide can be a suitable substitute for other composite materials in the tennis racket frame. By compression polymerization, polyamide was synthesized. The functionalization of Multi-walled carbon nanotube (MWCNT) was achieved using sulfuric acid and nitric acid, followed by ultrasonic preparation of nanocomposite materials with weight percentages of 5, 10, and 15. Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) confirmed a synthesized nanocomposite structure. Nanocomposites were tested for thermal resistance using the simultaneous thermal analysis (DTA-TG) method. scanning electron microscopy (SEM) analysis was used to determine pores' size, structure, and surface area. An X-ray diffraction analysis (XRD) analysis was used to determine their amorphous nature.