Earticle

본 논문에서는 새로운 무선 재난통신망인 위성 통신 무선패키지 시스템의 WLAN 중계기가 LTE D2D 이동 단말기와 접속시 인접한ISM 대역의 WALN 및 WPAN 시스템으로 부터 전파 채널 간섭을 Monte-Carlo 기반으로 분석을 하였다. 본 연구에서는 실 환경을고려 Extended Hata Model을 이용하여 WLAN Cell Radius를 구하고, 동일 채널에서 간섭원인 WLAN, Bluetooth, ZigBee로 부터의간섭을 최소화 하기 위한 물리적 보호 이격 거리와 Dense Mode에서 밀도를 시뮬레이션 하였다. 시뮬레이션 결과 WLAN 중계기는인접 WLAN과는 130m 이상 보호 이격 거리에서 15개의 간섭 기기와 운용 될 수 있고, Bluetooth와는 100m 이상 보호 이격 거리에서 23개의 간섭 기기와 운용 될 수 있으며, ZigBee와는 83m 이상에서 62개 간섭 기기와 운용 가능 함을 확인 하였다.

In this paper, when WLAN repeater of satellite communication package system as a novel wireless disaster communication network connected to LTE D2D mobile terminal, we analyzed radio channel interference from WLAN and WPAN system of adjacent same ISM band using Monte-Carlo method. In this study, WLAN cell radius was determined using Extended Hata Model considering practical environment, and simulated physical protection distance and density in the dense-mode to minimize interference from WLAN, Bluetooth, and ZigBee. Simulation results, WLAN repeater can be operated with 15 WLAN interferer over 130m distance, 23 Bluetooth interferer over 100m distance, and with 62 ZigBee interferer over 83m distance.

Background: The thermoluminescent dosimeter (TLD) and Monte Carlo (MC) dosimetry are carried out to determine the occupational dose for personnel in the handling of 125I seed sources. Materials and Methods: TLDs were placed in different layers of the Alderson-Rando phantom in the thyroid, lung and also eyes and skin surface. An 125I seed source was prepared and its activity was measured using a dose calibrator and was placed at two distances of 20 and 50 cm from the Alderson-Rando phantom. In addition, the Monte Carlo N-Particle Extended (MCNPX 2.6.0) code and a computational phantom with a lattice-based geometry were used for organ dose calculations. Results and Discussion: The comparison of TLD and MC results in the thyroid and lung is consistent. Although the relative difference of MC dosimetry to TLD for the eyes was between 4% and 13% and for the skin between 19% and 23%, because of the existence of a higher uncertainty regarding TLD positioning in the eye and skin, these inaccuracies can also be acceptable. The isodose distribution was calculated in the cross-section of the head phantom when the 125I seed was at two distances of 20 and 50 cm and it showed that the greatest dose reduction was observed for the eyes, skin, thyroid, and lungs, respectively. The results of MC dosimetry indicated that for near the head positions (distance of 20 cm) the absorbed dose rates for the eye lens, eye and skin were 78.1±2.3, 59.0±1.8, and 10.7±0.7 μGy/mCi/hr, respectively. Furthermore, we found that a 30 cm displacement for the 125I seed reduced the eye and skin doses by at least 3- and 2-fold, respectively. Conclusion: Using a computational phantom to monitor the dose to the sensitive organs (eye and skin) for personnel involved in the handling of 125I seed sources can be an accurate and inexpensive method.

3차원 탄성파탐사자료와 같은 대용량의 자료를 처리하기 위해서는 효율적인 자료처리기술이 요구된다. 자동속도분석방법은 속도스펙트럼을 이용하는 일반적인 NMO 속도분석에 필요한 자료처리시간과 인력을 줄일 수 있는 좋은 방법이다. 본 연구에서는 몬테카를로 방법을 이용한 자동속도분석 모듈을 개발하였고, 개발된 자동속도분석 모듈을 합성탄성파탐사자료와 현장자료에 적용해 보았다. 합성탄성파탐사자료는 서아프리카 연안의 균열대를 포함한 지하구조를 모사한 속도모델과 암염돔 구조를 포함한 지하구조를 모사한 속도모델로부터 얻어졌고, 현장자료는 2차원탄성파탐사에 의해 취득한 4383개의 공통중간점모음을 갖는 자료이다. 이 자료들에 개발된 자동속도분석 모듈을 적용하고, 그 결과를 수동속도분석의 결과와 비교하여 그 효율성을 분석하였다. 자동속도분석과 수동속도분석을 통해 얻은 속도를 적용한 중합단면도들의 비교를 통해 개발된 자동속도분석 모듈이 수동속도분석과 유사하게 중합단면도상에서 이벤트들의 연속성을 잘 보여주는 것을 확인하였다. 게다가 구간속도(vint)로부터 중합속도(vrms)를 구하는 본 연구에 사용된 자동속도분석 방법에 의해 얻어진 구간속도단면도가 중합속도로부터 구간속도를 구하는 수동속도분석에 의해 얻어진 구간속도단면도에 비해 지하구조의 속도변화에 민감하게 나타나는 것을 확인하였다.

Highly efficient processing techniques are required to deal with voluminous seismic data such as 3D seismic data. Automatic velocity analysis can be a good solution to reduce the processing time and labor in conventional NMO velocity analysis using velocity spectrums. In this study, we have developed an automatic velocity analysis module using Monte Carlo method and have applied it to synthetic and field data sets. One of the synthetic velocity models contains faults and the other includes a salt canopy. Those velocity models simulate the subsurface of the west coast of Africa. The marine field data set has 4383 CMP gathers obtained by 2D seismic survey. The developed automatic velocity analysis module has been tested its efficiency by comparing the results with those from the conventional manual velocity analysis. Stacked sections made by the developed automatic velocity analysis show coherent events similar to those by manual velocity analysis. Moreover, since our automatic velocity analysis method finds interval velocity (vint) first and then calculates a RMS velocity (vrms) function from vint, the vint section shows subsurface structure trend better than conventional manual velocity analysis.

The errors can cause the serious loss of the performance of a precision machine system. In this paper, we proposed the method of allocating the alignment tolerances of the parts and applied this method to get the optimal tolerances of a Confocal Scanning Microscope. In general, tight tolerances are required to maintain the performance of a system, but a high cost of manufacturing and assembling is required to preserve the tight tolerances. The purpose of allocating the optimal tolerances is minimizing the cost while keeping the high performance of the system. In the optimal problem, we maximized the tolerances while maintaining the performance requirements. The Monte Carlo Method, a statistical simulation method, is used in tolerance analysis. Alignment tolerances of optical components of the confocal scanning microscope are optimized to minimize the cost and to maintain the observation performance of the microscope. We can also apply this method to the other precision machine system.

본 연구는 의료용 선형가속기를 차폐하고 있는 차폐벽에 대하여 방사화 분석을 함으로서 추후 선형가속기 시설의 해체 시 해체비용의 절반이상을 차지하는 차폐벽에 대하여 폐기물 준위를 평가하고 이에 따른 폐기물 처리방법을 분석함으로서 해체비용 측면에 있어서 이득을 얻을 수 있는 방법에 대하여 논의하고자 한다. 실험결과, 선형가속기에서 발생하는 중성자 양은 차폐벽을 방사화 시키기에 충분한 양이 측정되었으며, 방사화 분석 결과 약 20 개 이상의 핵종이 분석되었다. 이 중 $^{24}Na$, $^{45}Ca$, $^{59}Fe$ 핵종이 규제해제 농도를 초과하는 것으로 분석되었으며, 그 값은 차폐벽 깊이가 깊어질수록 농도는 줄어들었다. 이를 바탕으로 특정 세 구역(E,F,G)은 매립이나 재활용이 불가능한 것으로 평가되었으며, 나머지 구역은 일정 깊이 이상일 경우 매립이나 재활용이 가능한 것으로 평가되었다.

This study analyzed for the radioactive shielding wall, which shields the medical linear accelerator. This allows to evaluate the level of waste with respect to the shield wall, which accounts for more than half of the cost of dismantling later linac facility. In addition, by analyzing the waste processing method according we discuss the way to obtain the benefits in terms of dismantling cost. Results of the simulate, the amount sufficient to screen the amount of neutron radiation occurring in the shielding wall linac was measured. And neutron activation analysis results were analyzed nuclides more than about 20. This analysis was in excess of that, $^{24}Na$, $^{45}Ca$, $^{59}Fe$ nucleus paper deregulation concentration. The value is reduced is greater the deeper the depth of the shielding wall concentration. Based on this, three specific areas (E, F, G) was estimated to be impossible to landfill or recycling. The rest area was estimated to be buried or recycled if possible more than a predetermined depth.

We analyze heat generation as well as temperature distribution induced by accelerated electron impact on a target in a closed x-ray tube. For the sake of accuracy, we use Monte carlo analysis. This method gives accurate energy deposit in a medium with additional information such as secondary and backscattered electron as well as their paths. A Tungsten coated layer is divided by small rectangular cell which accumulate energy loss of primary electron beam. The cells and their accumulated energy datum are used for the input of finite element analysis. The Maximum temperature rising and temperature distribution were analyzed by transient heat analysis. Some temperature parameters such as target size and coating thickness were varied to investigate temperature sensitivity. Temperatures were compared each other to find primary variable that affect temperature rising on the x-ray target. The results will be helpful in development highresolution x-ray tube and related industries.

본(本) 연구(硏究)에서는 특정지역에서 태풍(颱風)의 통계적(統計的) 분석(分析) 및 확률적(確率的) 기술방법(記述方法)을 이용하여 한국(韓國)의 태풍위험도분석(颱風危險度分析)에 관한 합리적(合理的) 방법(方法)을 제시(提示)하였다. 간접적(間接的) 방법(方法)으로 태풍(颱風)의 확률풍속(確率風速)을 예측하기 위해 두가지 시뮬레이션 과정(過程) 및 fitting 방법(方法)에 대해 논(論)하였다. 일반적으로 간접적(間接的) 방법(方法)으로는 Russell의 방법(方法)이 사용되고 있는데 이 방법(方法)은 특정지역에서 태풍(颱風)의 확률적(確率的) 예측을 위한 기상학적(氣象學的) 특성(特性)과 풍속장(風速場)모형(Wind field Model)에 기초를 두고 시뮬레이션 방법(方法)에 의해 약 1,000개의 태풍(颱風)을 발생시켜 통계적(統計的)으로 기저확률분포(基底確率分布)를 구한 다음, 그 결과를 Weibull분포(分布)에 fitting하도록 하고 있다. 그러나, 본(本) 연구(硏究)에서는 150년(年) 내지 200년간(年間)의 연최대풍속(年最大風速)을 발생시켜 그 data를 이용하여 Weibull분포(分布)에 직접 fitting하는 방법(方法)을 제안(提案)하였다. 수치해석(數値解析)결과, 본(本) 연구(硏究)에서 제안(提案)한 방법(方法)이 보다 효율적(效率的)이고 합리적(合理的)인 태풍(颱風)의 위험도평가방법(危險度評價方法)임을 알 수 있었다. 아울러, 제안(提案)된 확률풍속(確率風速) 예측방법(豫測方法)을 이용하여 태풍(颱風)취약지역인 남서해안(海岸) 일대에서 송전탑(送電塔)의 설계풍속(設計風速)에 대해 검토, 분석하였다.

This study proposes an operational method of typhoon risk assessments in Korea, using Statistical analysis and probabilistic description of typhoon at a site. Two alternative simulation and fitting methods are discussed to predict the probabilistic typhoon wind speeds by indirect methods. A Commonly used indirect method is Russell's procedure, which generates about 1,000 Simulation data for typhoon winds, statistically evaluate the base-line distribution, and then fits the results to the Weibull distribution based on probabilistic description of climatological Characteristics and Wind field model of typhoon at a site. However, an alternative procedure proposed in this Paper simulates extreme typhoon wind data of about 150~200 years and directly fits the generated data to the Weibull distribution. The computational results show that the proposed simulation method is more economical and reasonable for typhoon risk-assessment based on the indirect method. And using the proposed indirect method, the probabilistic design wind speed for transmission towers in typhoon-prone region along the South-Western coast is investigated.

본 연구는 Monte Carlo 기법을 교통카드기반의 수도권 지하철의 통행배정 문제에 적용하는 과정을 검토하였다. 연구는 우선 교통카드에서 역 간 표본의 통행에서 나타나는 통행시간에 대하여 프로빗 모형의 기반이 되는 정규분포의 가정을 적용하였다. Monte Carlo 통행배정은 역 간 통행에 대하여 평균과 표준편차를 산정하고 이를 개별 링크의 차내시간과 환승의 보행 및 배차간격의 가중치로 적용하는 방안을 제안하였다. 샘플 수가 50 이하로 낮게 나타나는 장 거리 통행은 유사 통행의 특성을 이전하는 방안으로 적용하였다. 수도권 지하철 네트워크에 대하여 두 가지 방향에서 연구 결과를 검토하였다. 하나는 선릉-성수의 단일 역 간 통행에 대 하여 차내시간 및 환승시간에 랜덤샘플링을 적용하는 방안으로 검증하였다. 다음으로 수도권 지하철 전체에 대해서는 역 간 통행 샘플수에 따라서 50 이상은 역 간 정규분포의 가정을 그대 로 수용하였다. 샘플수가 50 이하의 장거리 통행은 역 간 최소거리가 122 (Km)에서 표본의 균 등성이 확보되는 상황으로 판단하고 이 거리에서 나타나는 카드자료의 역 간 평균과 표준편차 를 적용하였다. 사례연구로서 교통카드자료로 구축된 수도권 지하철을 네트워크를 대상으로 단일OD 및 전체 OD의 통행배정의 결과를 도출하였다. 한편 통행에 대한 샘플링이 부족한 상 황에서 추가적인 연구가 필요한 것으로 나타났다.

This study reviewed the process of applying the Monte Carlo simulation technique to the traffic allocation problem of metropolitan subways. The analysis applied the assumption of a normal distribution in which the travel time information of the inter-station sample is the basis of the probit model. From this, the average and standard deviation are calculated by separating the traffic between stations. A plan was proposed to apply the simulation with the weights of the in-vehicle time of individual links and the walking and dispatch interval of transfer. Long-distance traffic with a low number of samples of 50 or fewer was evaluated as a way to analyze the characteristics of similar traffic. The research results were reviewed in two directions by applying them to the Seoul Metropolitan Subway Network. The travel time between single stations on the Seolleung-Seongsu route was verified by applying random sampling to the in-vehicle time and transfer time. The assumption of a normal distribution was accepted for sample sizes of more than 50 stations according to the inter-station traffic sample of the entire Seoul Metropolitan Subway. For long-distance traffic with samples numbering less than 50, the minimum distance between stations was 122Km. Therefore, it was judged that the sample deviation equality was achieved and the inter-station mean and standard deviation of the transport card data for stations at this distance could be applied.

방사선사고 시 내부오염 평가대상의 범위는 성인뿐만 아니라 소아까지 전 연령층으로 확대된다. 본 연구에서는 전신계수기의 측정 정확도를 향상시키기 위해 측정대상의 인체 크기와 측정 위치에 따른 계수효율을 평가하였다. 본 연구에서는 한국원자력의학원에서 사용하는 전신계수기인 FASTSCAN에 대해 방사선수송코드를 이용하여 전산 모사하였다.측정한 계수효율과 계산한 계수효율의 상대편중은 4세 소아의 경우 2% 이하이였으며, 성인의 경우에도 5% 이하로일치하였다. 측정 대상의 키가 작을수록 검출기와의 거리가 멀어지는 문제를 보완하고 인체 크기에 따른 계수효율의일관적인 경향성을 도출하기 위해, 측정대상의 측정 위치를 조절하여 전신계수기의 계수효율을 평가하였다. 조절된측정 위치에서의 전신계수기 계수효율을 바탕으로 측정 대상의 인체 크기 차이에 의한 내부오염도 평가 시 측정 오차를 줄일 수 있는 인체 크기 보정인자를 도출하였다. 도출된 보정인자는 전신계수기 측정결과에 곱하여 측정대상의내부오염도를 쉽게 평가할 수 있으며, 궁극적으로 방사선사고 시 전신계수기를 이용한 내부오염도의 측정 정확도를크게 향상시킬 수 있을 것이다.

For the case of radiation emergency, it is required to assess internal contamination of the public, including childrenas well as adults. The objective of the present study was to assess counting efficiency of a whole body counter by humanbody size and standing position of the measurement person. In this study, the FASTSCAN whole body counter used atNational Radiation Emergency Medical Center of Korean Institute of Radiological and Medical Science was simulated by aradiation transport computer code. The simulation results of the counting efficiencies agreed well with measurements withinthe 2% of discrepancy for 4-year child and 5% for adults. The standing positions of the people were adjusted by body sizeto find the consistent trend of the counting efficiencies by human body size. Body size scaling factors of the whole bodycounter were derived to consider human body size and improve the measurement accuracy. The counting efficiencyassessment methodology in this study can be successively used to improve the measurement accuracy when using a wholebody counter for the case of radiation emergency.

원전 방사선작업종사자의 내부선량평가를 위해 일반적으로 사용되고 있는 bed type 전신계측에 몬테카를로 방법을 적용하여 작업자에 대한 외부오염 계측특성을 평가하였다. 한국인 체형을 반영하는 voxel 모의 피폭체를 이용하여 내부오염시 측정 특성을 평가하였다. 외부오염 판별을 위해 BOMAB 모의 피폭체를 이용하여 신체 각 부위별 오염시 나타나는 측정 특성을 평가하였다. 가슴 부위 오염시 누운 자세와 엎드린 자세로 구분하여 외부오염시 계측 특성을 확인하였다. 정량적인 분석을 통해 bed type 전신계측기를 이용한 외부오염 판별이 가능함을 확인하였다.

Monte Carlo method was applied to discriminate the external contamination on radiation workers in nuclear power plants for internal dose assessment generally used with a bed type scanning detector whole body counter. Korean voxel model with internal contamination was used to estimate the detection patterns of whole body scanning. Also, the BOMAB model with various external contamination was assumed to compare with detection of radionuclides inside the human body. From the comparison of detection efficiency between front and back side up, external contamination was easily distinguished.

In this study, we estimated the number of secondary COVID-19 infections caused by students with potential transmission potential home. When the existing Monte Carlo method was applied to Korean data, the average number of household members of the second COVID-19 infected was predicted. The summary of this study is as follows. First, in general, the number of secondary infections by students returning home from school is greatly influenced by the virus infection rate of each student group they contact while returning home from school. Korea-based empirical research on this is needed. Second, the number of secondary infections by Korean students was relatively lower than that of previous studies. This can be interpreted as being due to the domestic furniture structure. Third, unlike previous studies that assumed the distribution of secondary infected individuals as normal distribution, assuming a negative binomial distribution, the number of secondary infected individuals was sensitively changed according to the estimated parameters. Interpretation of this result shows that the number of secondary infections may vary depending on the time of decision making, the target region, and the target student group. Finally, according to the results of this analysis, a proposal was made to support education policy decisions.

Skyshine은 고에너지 가속기의 차폐 설계 시 반드시 고려되는 중요한 현상이다. 본 연구에서는 고에너지 전자 가속기에 대한 중성자 skyshine 평가 방법을 새롭게 제시하였으며 기존의 방법들과 비교하여 타당성을 검증하였다. 고에너지 전자가속기로부터 원거리 지역의 방사선량을 계산하기 위해 몬테카를로 코드, FLUKA와 PHITS를 이용하였다. 가속기 건물로부터 원거리 지역까지 도달하는 방사선장의 경로를 skyshine, direct, groundshine, multiple-shine으로 분류하였다. 분류된 각각의 성분이 총 유효선량에 기여하는 정도를 평가하였다. 방사선원 계산에는 10 GeV 전자가 두꺼운 표적에 입사하여 생성되는 중성자를 고려하였다. Groundshine 효과를 평가하기위해 PAL-XFEL의 건설부지토양에 대한 성분을 고려하였다. 가속기 건물로부터 비교적 가까운 50 m 미만에서는 direct와 groundshine 성분들이 총 유효선량에 대부분 기여하였다. 가속기 터널로부터 거리가 멀어질수록 skyshine 성분의 기여도가 증가하였다. 평가된 skyshine 성분에 대한 유효선량은 기존에 skyshine 선량을 계산할 때 사용되었던 반실험식 중 전자가속기를 이용한 실험결과에 기반한 Rindi의 식과 가장 잘 일치하였다. 간이계산코드 SHINE3의 결과와 20% 이내로 일치하였다. 모든 성분이 포함된 총 유효선량은 기존의 평가방식에 비해 10배 정도 크게 평가되었다. 가속기 터널로부터 원거리 지역에 대한 선량평가계산에서 mutiple-shine 성분의 영향은 skyshine 성분보다 더 크다는 것을 확인하였다.

The skyshine effect is an essential and important phenomenon in the shielding design of the high energy accelerator. In this study, a new estimation method of neutron skyshine was proposed and was verified by comparison with existing methods. The effective dose of secondary neutrons and photons at the locations that was far away from high-energy electron accelerator was calculated using FLUKA and PHITS Monte Carlo code. The transport paths of secondary radiations to reach a long distance were classified as skyshine, direct, groundshine and multiple-shine. The contribution of each classified component to the total effective dose was evaluated. The neutrons produced from the thick copper target irradiated by 10 GeV electron beam was applied as a source term of this transport. In order to evaluate a groundshine effect, the composition of soil on the PAL-XFEL site was considered. At a relatively short distance less than 50 m from the accelerator tunnel, the direct and groundshine components mostly contributed to the total effective dose. The skyshine component was important at a long distance. The evaluated dose of neutron skyshine agreed better with the results using Rindi’s formula, which was based on the experimental results at high energy electron accelerator. That also agreed with the estimated dose using the simple evaluation code, SHINE3, within about 20%. The total effective dose, including all components, was 10 times larger than the estimated doses using other methods for this comparison. The influence of multiple-shine path in this evaluation of the estimation method was investigated to be bigger than one of pure skyshine path.

In this paper, we analyzed the adjacent channel interference of the LTE band 40 defined by 3GPP on the WLAN system based on the Monte-Carlo method, and found the guard band required for compatibility between the two systems. This study have a difference compared to the previous studies about cell radius was determined using Extended Hata Model considering practical environment, interference protection distance related to guard band, and the spectrum emission mask improvement effect for minimizing the interference. Simulation results, for no channel interference compatibility of LTE and WLAN for mobile satellite wireless package system, we can find the need 15MHz guard band at specified spectrum emission mask and 10MHz guard band at assumed spectrum emission mask.

The spectrum of the random space vector pulse width modulation (SVPWM) strategy is extremely complicated due to the random variable. A new algorithm based on the Monte Carlo method is proposed to optimize and customize the frequency spectrum of the random SVPWM strategy. A universal theoretical spectrum computation method is given for the SVPWM strategy firstly. In addition, the key procedure of the proposed algorithm is presented. Finally, several computation examples are provided to verify the effectiveness and feasibility. The analysis and computation examples show that the proposed algorithm has several advantages, and the results verify its convenience and feasibility.