• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.137-143
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• 2002

This paper concerns the spin-stabilization for the second stage of KSR-III(Korea Sounding Rocket-III). The error sources in the second stage are defined, and then the effect on attitude error of KSR-III is analyzed quantitatively and qualitatively. Based on the analysis, some conditions for optimal spinning frequency and optimal steady-spinning duration are suggested. Among several solutions, an optimal value can be determined in the point of minimum impact-point error. An approach to a sub-optimal solution is also suggested. Application to the KSR-III shows that a proper spinning frequency and a steady-spin duration to give the smallest impact-point error can be effectively determined.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.107-113
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• 2000

Purpose : The goal of this study 닌as to improve the accuracy of three-dimensional conformal radiotherapy (3-D CRT) by measuring the treatment setup error and physiological movement of liver based on the analysis of images which were obtained by electronic portal imaging device (EPID). Materials and Methods : For 10 patients with hepatocellular carcinoma, 4-7 portal images were obtained by using EPID during the radiotherapy from each patient daiiy. We analyzed the setup error and physiological movement of liver based on the verification data. We also determined the safety margin of the tumor in 3-D CRT through the analysis of physiological movement. Results : The setup errors were measured as 3mm with standard deviation 1.70 mm in x direction and 3.7 mm with standard deviation 1.88 mm in y direction respectively. Hence, deviation were smaller than 5mm from the center of each axis. The measured range of liver movement due to the physiological motion was 8.63 mm on the average. Considering the motion of liver and setup error, the safety margin of tumor was at least 15 mm. Conclusion : EPID is a very useful device for the determination of the optimal margin of the tumor, and thus enhance the accuracy and stability of the 3-D CRT in patients with hepatocellular carcinoma.

• Proceedings of the KSRS Conference
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• 2008.03a
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• pp.207-212
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• 2008

연구에서는 SPOT-3 인공위성 영상으로부터 얻어진 영상 스테레오 스트립과 GCP(Ground Control Point)자료를 이용하여 다양한 GCP배치에 따른 궤도기반 센서모델의 정확성에 대해 분석하였다. 실험에 사용된 기준점자료는 춘천지역에서부터 나주지역에 이르기 까지 약 420km 길이의 지역에 대해 GPS측량을 통해 획득하였다. 궤도기반 센서모델에 적용된 미지수는 위성의 위치와 속도, 자세를 표현하는 방정식의 계수를 미지수로 선택하여 일곱 가지 방식으로 조합하였다. 실험은 우선 모델점의 위치를 일곱 가지 경우로 결정하고 각 경우에 대해 일정한 개수의 모델점을 선택하였다. 그리고 각 경우의 모델점의 위치에 대해 궤도기반 센서모델의 미지수 조합 모델을 각 각 다르게 적용해 본 후 그 결과를 시각적, 수치적으로 분석해 보았다. 실험 결과 모델점의 위치에 관계 없이 궤도기반 모델에 적용할 수 있는 높은 정확도를 나타내는 미지수 조합모델을 찾아낼 수가 있었고, 여러 가지 모델점의 위치를 궤도기반 센서모델에 적용해 본 결과 지리적, 시간적, 경제적 효율성을 갖는 최적의 미지수 조합을 찾을 수가 있었다.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.60-60
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• 2003

목적 : 감마나이프 치료계획용 소프트웨어인 감마플렌에서 처방선량을 계산하는 단위와 실제 시간을 설정하는 하드웨어인 조정판의 시간설정 단위의 차이에 의한 실제 처방선량에 끼치는 영향을 계산하였다. 대상 및 방법 : 감마나이프는 주어진 4 개의 헬멧을 가지고 최소 한번 또는 최대 20 번 이상의 방사선 조합으로 한번에 많은 방사선을 목표물에 조사한다. 감마나이프 방사선 수술을 위한 치료계획용 소프트웨어인 감마플렌 5.32에서는 처방선량에 대한 치료시간을 최대 지점 또는 지정하는 지점에 규격화하여 소숫점 두 자리 즉 0.6 초까지 계산한다. 그러나 실제 치료를 위한 조정판의 시간설정은 모델 B 에서는 소숫점 한자리까지 가능하게 되어있다. 그러므로 모델 B를 사용하는 기관의 치료계획 컴퓨터인 감마플렌에서는 소숫점 한자리로 만들기 위해 반올림과 내림을 하게 되며 이것을 프린트하여 사용하게 된다. 실제 임상에서 멀티삿에 대한 반올림과 내림에 대한 효과를 선량으로 환산하여 처방선량에 끼치는 영향을 연구하였다. 치료 계획에 서 처방선량을 입력한 후 계산된 각 조사에 대한 소숫점 두자리 시간을 화면에 표시한 후 스냅tit으로 스크린 캡쳐하여 프린트하였으며, 소숫점 한자리로 된 최종 치료계획을 프린트하여 서로 비교 계산하였다. 결과 : 20 여명의 환자에 대한 치료 결과에 대한 분석은 조사의 수나 처방선량에 관계하지 않고 우연히 올림이 많으냐 내림이 많으냐에 의존하였다. 최대지점에 대하여 분석한 결과는 -0.48부터 +0.47로 -2%부터 +1.9%의 정도로 영향을 끼쳤다. 결론 : 반올림과 내림의 결과는 처방선량을 줄일 수도 있고 늘일 수도 있었다. 그러나 이 연구는 최대선량 지점에 대해 비교를 하였으나 실제로는 각 조사의 위치가 서로 다르므로 영향은 이보다 훨씬 적을 것으로 생각되어 소숫점 한자리로 치료하여도 무방할 것으로 보인다.mm, AP 방향에서는 2.1$\pm$0.82 mm이었다. 그리고 복부의 later의 방향에서는 7.0$\pm$2.1 mm, AP 방향에서는 6.5$\pm$2.2 mm 이었다. 또한 표적 위치측정을 위해서 환자의 피부에 임의의 가상표적을 부착하고 CT 촬영한 영상결과, 프레임으로 가상표 적에 대한 위치를 정확히 파악할 수 있었다. 결론 : 제작된 프레임을 적용하여 방사선투과율 측정실험, 환자 외부자세에 대한 오차 측정실험, 가상표적 위치측정 실험 등을 수행하였다. 환자 외부자세에 대한 오차 측정실험 경우, 더 많은 Volunteer를 적용하여 보다 정확한 오차 측정실험이 수행되어야 할 것이며 정확한 표적 위치 측정실험을 위해서 내부 마커를 삽입한 환자를 적용한 임상실험이 수행되어야 할 것이다. 또한 위치결정에서 획득한 좌표값의 정확성을 알아보기 위해서 팬톰을 이용한 방사선조사 실험이 추후에 실행되어져야 할 것이다. 그리고 제작된 프레임에 Rotating X선 시스템과 내부 장기의 움직임을 계량화하고 PTV에서의 최적 여유폭을 설정함으로써 정위 방사선수술 및 3 차원 업체 방사선치료에 대한 병소 위치측정과 환자의 자세에 대한 setup 오차측정 결정에 도움이 될 수 있을 것이라고 사료된다. 상대적으로 우수한 것으로 나타났으며, 혼합충전재는 암모니아의 경우 코코넛과 펄라이트의 비율이 7：3인 혼합 재료 3번과 소나무수피와 펄라이트의 비율이 7：3인 혼합 재료 6번에서 다른 혼합 재료에 비하여 우수한 것으로 나타났다. 4. 코코넛과 소나무수피의 경우 암모니아 가스에 대한 흡착 능력은 거의 비슷한 것으로 사료되며, 코코넛의 경우 전량을 수입에 의존하고 있다는 점에서 국내 조달이 용이하며, 구입 비용도 적게 소요되는 소나무수피를 사용하는 것이 경제적이라고 사료된다. 5. 마지막으로

• The Journal of Korean Society for Radiation Therapy
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• v.32
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• pp.61-71
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• 2020

Purpose: To investigate the effect of collimator angle on plan quality of PAN-Pelvis Multi-isocenter VMAT plan, dose reproducibility at the junction and impact on set-up error at the junction. Material and method: 10 adult patients with whole pelvis cancer including PAN were selected for the study. Using Trubeam STx equipped with HD MLC, we changed the collimator angle to 20°, 30°, and 45° except 10° which was the default collimator angle in the Eclipse(version 13.7) and all other treatment conditions were set to be the same for each patient and four plans were established also. To evaluate these plans, PTV coverage, coverage index(CVI) and homogeneity index (HI) were compared and clinical indicators for each treatment sites in normal tissues were analyzed. To evaluate dose reproducibility at the junction, the absolute dose was measured using a Falmer type ionization chamber and dose changes at the junction were evaluated by moving the position of the isocenter in and out 1~3mm and setting up the virtual volume at the junction. Result: CVI mean value was PTV-45 0.985±0.004, PTV-55 0.998±0.003 at 45° and HI mean value was PTV-45 1.140±0.074, and PTV-55 1.031±0.074 at 45° which were closest to 1. V20Gy of the kidneys decreased by 9.66% and average dose of bladder and V30 decreased by 1.88% and 2.16% at 45° compared to 10° for the critical organs. The dose value at the junction of the plan and the actual measured were within 0.3% and within tolerance. At the junction, due to set-up error the maximum dose increased to 14.56%, 9.88%, 8.03%, and 7.05%, at 10°, 20°, 30°, 45°, and the minimum dose decreased to 13.18%, 10.91%, 8.42%, and 4.53%, at 10°, 20°, 30°, 45° Conclusion: In terms of CVI, HI of PTV and critical organ protection, overall improved values were shown as the collimator angle increased. The impact on set-up error at the junction by collimator angle decreased as the angle increased and it will help improve the anxiety about the set up error. In conclusion, the collimator angle should be recognized as a factor that can affect the quality of the multi-isocenter VMAT plan and the dose at the junction, and be careful in setting the collimator angle in the treatment plan.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2693-2696
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• 2003

The national standard physique research of Korea is being conducted every 5-6 year term after its first research was started in 1979, the fourth research was conducted in 1997. The result of the national physique research was reflected in manufactured goods design of allied industries such as clothing, shoes, furniture. In this thesis, we measured anthropometry value for every bodily figurative classification after dividing users according to gender, age, bodily figure using the result of the national standard physique research. We constructed 3D character through the process of analyzing interrelation of measured anthropometry and measuring representative category. For the process for organization, we measured anthropometry which can express sports action of golf, tennis and etc effectively. We made it by Presenting measurement which is able to form each type of 3D character after the category was decided. Quantitative and objective valuation for posture and action became possible by developing visible information offer and posture action analysis protocol in theoretical approach for analysis of posture and action in sports.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.631-634
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• 2006

The national standard physique research of Korea is being conducted every 5$\sim$6 year term after its first research was started in 1979. The result of the national physique research was reflected in manufactured goods design of allied industries such as clothing, shoes, furniture. In this thesis, we measured anthropometry value for every bodily figurative classification after dividing users according to gender, age, bodily figure using the result of the national standard physique research. We constructed 3D character through the process of analyzing interrelation of measured anthropometry and measuring representative category. For the process for organization, we measured anthropometry which can express sports action of golf, tennis and etc effectively. We made it by presenting measurement which is able to form each type of 3D character after the category was decided. Quantitative and objective valuation for posture and action became possible by developing visible information offer and posture action analysis protocol in theoretical approach for analysis of posture and action in sports.

• Science of Emotion and Sensibility
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• v.6 no.2
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• pp.59-64
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• 2003

The national standard anthropometry of Korea is conducted every 5∼6 year term after its first research was started in 1979, The fourth research was conducted in 1997. The result of the national standard anthropometry has been reflected in manufactured goods design of allied industries such as clothing, shoes and furniture. In this paper, we measured anthropometry data for every bodily figurative classification after dividing users according to gender, age and bodily figure using the result of the national standard anthropometry. We constructed 3D character through the process of analyzing interrelation of measured anthropomeoy and measuring representative category. In the process for organization , we measured anthropometry which can effectively express sports action of golf, tennis etc. We made it by presenting measurement which is able to form each type of 3D character after the category was decided. Quantitative and objective valuation for posture and action became possible by developing visible information offer and posture action analysis protocol in theoretical approach for analysis of posture and action in sports.

• Journal of Astronomy and Space Sciences
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• v.20 no.3
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• pp.205-216
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• 2003

The attitude motion of a spin-stabilized, upper-stage spacecraft is investigated based on a two-body model, consisting of a symmetric body, representing the spacecraft, and a spherical pendulum, representing the liquid slag pool entrapped in the aft section of the rocket motor. Exact time-varying nonlinear equations are derived and used to eliminate the drawbacks of conventional linear models. To study the stability of the spacecraft's attitude motion, both the spacecraft and pendulum are assumed to be in states of steady spin about the symmetry axis of the spacecraft and the coupled time-varying nonlinear equation of the pendulum is simplified. A quasi-stationary solution to that equation and approximate resonance conditions are determined in terms of the system parameters. The analysis shows that the pendulum is subject to a combination of parametric and external-type excitation by the main body and that energy from the excited pendulum is fed into the main body to develop the coning instability. In this paper, numerical examples are presented to explain the mechanism of the coning angle growth and how angular momenta and disturbance moments are generated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.12
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• pp.865-873
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• 2019

To improve the survivability of a missile, it needs to be lowered that the detection possibility by radars on the ground. The radar exposure of the target is given as a function of relative distance from the radar to the target and RCS (Radar Cross Section). The RCS of the missile is determined by the incidence angle of the target to electromagnetic radiation emitted from the radar. Under the assumption that the missile equips appropriate attitude control system, the attitude of the missile to minimize radar exposure at a high altitude is investigated in this paper. Two different types of performance cost are considered: the total sum of RCS and the total sum of SNR during the flight. Optimal solutions against multiple ground radars are found by using a SQP (Sequential Quadratic Programming)-based optimization technique.