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김현석,예성준,이계민,김기현 한국물리학회 2019 Current Applied Physics Vol.19 No.7
The purpose of this study is to optimize the collimator mask design for the rotational modulation collimator (RMC) imaging system. First, we optimized the slat and slit width of the collimator mask which affects the number of particles entering the detector and, thus, alters the morphology of modulation patterns. However, the conventional collimator mask design with bilateral symmetry posed an inherent ambiguity issue in the estimation of the source location in the reconstructed image. Therefore, we propose a new asymmetric collimator mask design which can solve the ambiguity problem for the development of the dual-particle imaging system. Modulation patterns for various types of asymmetric mask designs were calculated with Monte Carlo simulations, and modulation and transmission efficiencies were compared with ones for the conventional RMC mask design to evaluate the nominal performance of the new mask designs. The proposed asymmetric collimator mask removed the ambiguous artifact from the reconstructed image without compromising transmission and modulation efficiencies. In addition, one can even expect to achieve better spatial resolution in the reconstructed image with the proposed new asymmetric mask design, as compared with the asymmetric mask design suggested from the previous study.
오피스 건물 등급 설정을 위한 세부 시설계획 평가 방안 제안
김덕현,예성준,이경태,임진빈,김주형 대한건축학회 2023 대한건축학회논문집 Vol.39 No.9
오피스 건물 임대자산관리에서 등급 평가는 투자 의사 결정에 중요한 사항이다. 우리나라 오피스 건물의 등급 평가는 민간 부동산 업체들의 자체적인 획일되지 않은 기준으로 평가되어왔다. 또한, 대다수의 평가 기준은 임대인 중심의 가치평가에 중점을 두고 있으며 등급 평가에 대한 세부적인 시설기준이 마련되어있지 않다. 이러한 상황은 공급업체와 투자자가 검증된 오피스 빌딩 자산의 품질을 선택하는데 혼란을 불러오고 있다. 본 연구의 목적은 세부 시설기준이 명확하게 구분되어있는 등급 평가의 방향을 제시하는 것이다. 실무자를 대상으로 이전 연구들과 국내·외 부동산업체들의 오피스 등급 평가항목 및 기준들의 검증을 통해 평가 항목을 재정립하였다. 재정립된 평가 항목은 60개로 분류되었으며 포커스 그룹 인터뷰를 통해 수립되었다. 신규 평가 항목을 수치적으로 정량화하기 위해 리커트 5점 척도를 사용하여 각 항목에 대한 배점표를 도출하였다. 이러한 접근방식을 바탕으로 종합점수 산정방법을 수립하고 오피스 건물에 대한 5가지 등급제를 제안하였다. 실제 사례에 대한 샘플 평가를 통해 실제 사용성능에 가까운 평가가 가능함을 확인하였다. 본 연구를 통해 제안된 평가 방안은 오피스 사업 시행자의 계획 수립과 임차인의 오피스 임대 시, 판단에 도움을 줄 수 있을 것이라 기대된다. In managing office building assets, grading assessment plays a crucial role in making investment decisions. In Korea, the grading assessmentof office buildings has been handled by private real estate companies, following an inconsistent and sporadic analysis method. Consequently,specific facility criteria for evaluating the grade of office buildings haven’t been standardized. This lack of clarity can create confusion forboth suppliers and investors seeking reliable building assets. This study aims to establish precise facility standards and provide a cleardirection for distinctive grading assessments. To achieve this, the current evaluation criteria were redefined after validating the revisedguidelines with industry practitioners. These redefined criteria were organized into 60 items, which were then verified through focus groupinterviews. To quantify these criteria, a scoring table was devised for each item using a 5-point Likert scale. Using this approach, acomprehensive scoring method was established and five rating systems for office buildings were proposed. By applying this approach to anactual case, it was confirmed that the evaluation closely aligned with real-world performance. This proposed evaluation method is anticipatedto assist business operators in their planning efforts and aid tenants in making informed decisions when renting office spaces.
박소연,박종민,예성준 대한방사선방어학회 2011 방사선방어학회지 Vol.36 No.4
To quantitatively evaluate how setup errors in conjunction with dose gradients contribute to the error in IMRT dose quality assurance (DQA) measurements. The control group consisted of 5 DQA plans of which all individual field dose differences were less than ±5%. On the contrary, the examination group was composed of 16 DQA plans where any individual field dose difference was larger than ±10% even though their total dose differences were less than ±5%. The difference in 3D dose gradients between the two groups was estimated in a cube of 6 × 6 × 6 mm^3 centered at the verification point. Under the assumption that setup errors existed during the DQA measurements of the examination group, a three dimensional offset point inside the cube was sought out, where the individual field dose difference was minimized. The average dose gradients of the control group along the x, y, and z axes were 0.21, 0.20, and 0.15 cGy․mm^(-1), respectively, while those of the examination group were 0.64, 0.48, and 0.28 cGy․mm^(-1), respectively. All 16 plans of the examination group had their own 3D offset points in the cube. The individual field dose differences recalculated at the offset points were mostly diminished and thus the average values of total and individual field dose differences were reduced from 3.1% to 2.2% and 15.4% to 2.2%, respectively. The offset distribution turned out to be random in the 3D coordinate. This study provided the quantitative data that support the large individual field dose difference mainly stems from possible geometric errors (e.g., random setup errors) under the influence of steep dose gradients of IMRT field.
엄민기,윤석원,예성준 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.11
Miniaturized tissue equivalent proportional counters (mini-TEPCs) are proper for radiation dosimetry in medical application because the small size of the dosimeter could prevent pile-up effect under the high intensity of therapeutic beam. However, traditional methods of calibrating mini-TEPCs using internal alpha sources are not feasible due to their small size. In this study, we investigated the use of electron and proton edges on Monte Carlo-generated lineal energy spectra as markers for calibrating a 0.9 mm diameter and length mini-TEPC. Three possible markers for each spectrum were calculated and compared using different simulation tools. Our simulations showed that the electron edge markers were more consistent across different simulation tools than the proton edge markers, which showed greater variation due to differences in the microdosimetric spectra. In most cases, the second marker, yδδ, had the smallest uncertainty. Our findings suggest that the lineal energy spectra from mini-TEPCs can be calibrated using Monte Carlo simulations that closely resemble real-world detector and source geometries.