• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.4 s.56
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• pp.180-187
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• 2009

The objective of this research is to verify the code-specified girder distribution factors (GDF) for continuous steel girder bridges by field testing. Previous analytical study revealed that current GDF's specified in AASHTO Standard and AASHTO LRFD, developed for the simple span bridges are conservative even for the continuous bridges. In this study, field tests were performed for three continuous steel girder bridges to validate the GDF's specified in the AASHTO codes. The results show that the code values are conservative when compared with field tests, and in some cases, too conservative. Also, strains measured from the field test are, in most cases, smaller than those expected from the analytical results. However, when the GDF's from measured strains are compared with GDF's from analysis, it is found that the analysis results are not conservative, and in some instance, the analytical results underestimate the actual GDF's, which can lead to a groundless notion of safety. In one case, test results showed that the code GDF's specified in AASHTO LRFD is too permissive. As a result, it is found that GDF's specified in AASHTO LRFD should be used with careful reservation.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.25-32
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• 2019

This paper proposes the method of an in-vehicle gateway to reduce the reprogramming time for the ECU (Electronic Control Unit). In order to reduce the reprogramming time, the gateway must prohibit transmitting messages, that are not related to reprogramming, to the destination CAN network, and no ECU should diagnose the DTC(Diagnostic Trouble Code) that indicates CAN communication error caused by prohibiting CAN messages by the gateway. Moreover, STmin, which are the minimum time between two consecutive CAN messages, should be minimized. In order to do this, this paper proposes the method that uses the link control command specified in UDS(Unified Diagnostic Services) and hardware based gateway functionality that are supported by the latest MCU(Micro Controller Unit). The proposed method is developed using TC275 based embedded system, and its results are presented.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.301-308
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• 2024

Ceramic materials are being explored as alternatives to toxic lead sheets for radiation shielding due to their favorable properties like durability, thermal stability, and aesthetic appeal. However, crafting effective ceramics for radiation shielding entails complex processes, raising production costs. To investigate local viability, this study evaluated Malaysian ceramic tiles for shielding in diagnostic X-ray rooms. Different ceramics in terms of density and thickness were selected from local manufacturers. Energy Dispersive X-ray Fluorescence (EDXRF) and X-ray Fluorescence (XRF) characterized ceramic compositions, while Monte Carlo Particle and Heavy Ion Transport code System (MC PHITS) simulations determined Linear Attenuation Coefficient (LAC), Half-value Layer (HVL), Mass Attenuation Coefficient (MAC), and Mean Free Path (MFP) within the 40-150 kV energy range. Comparative analysis between MC PHITS simulations and real setups was conducted. The C3-S9 ceramic sample, known for homogeneous full-color structure, showcased superior shielding attributes, attributed to its high density and iron content. Notably, energy levels considerably impacted radiation penetration. Overall, C3-S9 demonstrated strong shielding performance, underlining Malaysia's potential ceramic tile resources for X-ray room radiation shielding.

• Journal of Radiation Protection and Research
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• v.27 no.3
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• pp.155-164
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• 2002

Methodology to evaluate the effective doses to adults undergoing various diagnostic x-ray examinations were established by Monte Carlo simulation of the x-ray examinations. Anthropomorphic mathematical phantoms, the MIRD5 male phantom and the ORNL female phantom, were used as the target body and x-ray spectra were produced by the x-ray spectrum generation code SPEC78. The computational procedure was validated by comparing the resulting doses to the results of NRPB studies for the same diagnostic procedures. The effective doses as well as the organ doses due to chest, abdomen, head and spine examinations were calculated for x-rays incident from AP, PA, LLAT and RLAT directions. For instance, the effective doses from the most common procedures, chest PA and abdomen AP, were 0.029 mSv and 0.44 mSv, respectively. The fact that the effective dose from PA chest x-ray is far lower than the traditional value of 0.3 mSv(or 30 mrem), which results partly from the advances of technology in diagnostic radiology and partly from the differences in the dose concept employed, emphasizes necessities of intensive assessment of the patient doses in wide ranges of medical exposures. The methodology and tools established in this study can easily be applied to dose assessments for other radiology procedures; dose from CT examinations, dose to the fetus due to examinations of pregnant women, dose from pediatric radiology.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.282-293
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• 2021

This paper examines gamma-ray shielding properties of SBC-Bx glass system with the chemical composition of 40SiO₂-10B₂O₃-xBaO-(45-x)CaO- yZnO- zMgO (where x = 0, 10, 20, 30, and 35 mol% and y = z = 6 mol%). Mass attenuation coefficient (µ/ρ) which is an essential parameter to study gamma-ray shielding properties was obtained in the photon energy range of 0.015-15 MeV using PHITS Monte Carlo code for the proposed glasses. The obtained results were compared with those calculated by WinXCOM program. Both the values of PHITS code and WinXCOM program were observed in very good agreement. The (µ/ρ values were then used to derive mean free path (MFP), electron density (N_eff), effective atomic number (Z_eff), and half value layer (HVL) for all the glasses involved. Additionally, G-P method was employed to estimate exposure buildup factor (EBF) for each glass in the energy range of 0.015-15 MeV up to penetration depths of 40 mfp. The results reveal that gamma-ray shielding effectiveness of the SBC-Bx glasses evolves with increasing BaO content in the glass sample. Such that SBC-B35 glass has superior shielding capacity against gamma-rays among the studied glasses. Gamma-ray shielding properties of SBC-B35 glass were compared with different conventional shielding materials, commercial glasses, and newly developed HMO glasse. Therefore, the investigated glasses have potential uses in gamma shielding applications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.725-730
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• 2002

This paper presents an efficient modeling method for open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of open cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the difficulty and numerical errors in association with re-meshing the structure. The proposed method is rigorously compared with a commercial finite element code. Experiments are also performed to validate the proposed modeling method. Finally, a diagnostic scheme for open cracked beam structures is proposed and demonstrated through a numerical example.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1345-1348
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• 2003

본 논문에서는 CDMA(Code Division Mutiple Access) 단말기의 상태를 점검하고 제어하는 DM(Diagnostic Monitor) 기능을 CDMA 무선망인 IS-95/A/B/C 및 1X 무선망을 이용하여 사용 할 수 있도록 제안하였다. 기존의 방식은 필드에서 사용중인 단말기의 A/S 또는 필드의 상황 파악을 위해 단말기 개발자가 장비를 가지고 그곳으로 가야하는 시간적, 공간적인 한계가 있었다. 이를 보완하기 위해서 CDMA 무선망에서 SMS(Short Message Service) 프로토콜을 이용하여 원격으로 단말기 상태점검 및 제어, 기지국과 단말기간의 인터페이스 유지보수 등을 할 수 있는 프로토콜을 제안한다. 제안된 프로토콜을 이용한 실험을 통하여 실제 필드에서 단말기를 제어하는 것과 동일한 제어가 가능하고 필드 환경 상태를 직접 가지 않고도 알아낼 수 있는 등 단말기 개발 및 유지보수에 많은 이득을 가져다 줄 수 있음을 입증한다.

• Communications for Statistical Applications and Methods
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• v.24 no.6
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• pp.583-604
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• 2017

The most popular regression model for the analysis of time-to-event data is the Cox proportional hazards model. While the model specifies a parametric relationship between the hazard function and the predictor variables, there is no specification regarding the form of the baseline hazard function. A critical assumption of the Cox model, however, is the proportional hazards assumption: when the predictor variables do not vary over time, the hazard ratio comparing any two observations is constant with respect to time. Therefore, to perform credible estimation and inference, one must first assess whether the proportional hazards assumption is reasonable. As with other regression techniques, it is also essential to examine whether appropriate functional forms of the predictor variables have been used, and whether there are any outlying or influential observations. This article reviews diagnostic methods for assessing goodness-of-fit for the Cox proportional hazards model. We illustrate these methods with a case-study using available R functions, and provide complete R code for a simulated example as a supplement.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.197-204
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• 2003

This paper presents an efficient modeling and dynamic analysis method for open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the inconvenience and numerical errors in association with re-meshing the structural model with the crack position changed. The proposed modeling method is validated through a series of simulation and experiments. First, the proposed method is rigorously compared with a commercial finite element code. Then, two kinds of experiments are performed to validate the proposed modeling method. Finally, a diagnostic scheme fur open cracked beam structures is proposed and demonstrated through a numerical example.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1157-1158
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• 2007

자동차, 항공기, 철도 및 선박 등과 같은 각종 교통수단에 발생하는 이상현상에 대한 사용자의 정확한 복구 조치 능력 향상을 위하여, 발생한 고장코드에 대한 신속하고 정확한 해석은 매우 중요하다. 이에 따라 본 논문에서는 차량의 고장 진단 프로토콜 중 SAE(미국 자동차 기술자 협회) J1979[1]의 방식을 사용하여 차량의 통신방식을 정의 하고 이에 따라 발생되는 ECU 정보들을 수집 분석하여 각각의 고장 코드들을 해석하였고 배기가스뿐만 아니라 차량에서 발생되는 총제적인 문제점들을 GUI(Graphic User Interface) 기반의 응용 프로그램을 이용하여 차량의 단계별, 부품별 고장코드를 실시간으로 발생시킬 수 있는 시뮬레이터를 개발하였다