Fire Resistance of Hybrid Floor Based on Small-Scale Furnace Tests and Energy-Based Time Equivalent Approach

박민재,배재훈,류재호,주영규 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.6

A novel hybrid floor, which was a prefabricated composite system infilled using polymers with hollow cores between its top and bottom steel plates, was previously developed for application in steel structures. In addition, the structural performance of the steel floor, including its bending capacity, floor vibration, and dynamic characteristics, were investigated. However, as the fire resistance performance of the hybrid floor had not been investigated, it was installed in actual buildings using insulating materials, which caused problems, such as a dirty workplace and additional work that prolonged the construction period. In this study, small-scale furnace tests, whose specimens have fewer variables in comparison with those of full-scale tests, were conducted instead of full-scale furnace tests to analyze the effects of various variables on the fire resistance performance of the hybrid floor. In fact, the heating curves obtained via the small-scale furnace tests were not similar those suggested by Korean Standards (KS). The energy-based time equivalent approach was applied to calibrate the results. Thus, the fire resistance ratings were estimated based on small-scale furnace tests via the energy-based time equivalent approach with respect to polymer thickness and aspect ratio, which were expressed using the lengths and widths of the specimens.

한국형 레몬법을 이용한 이차원적 보증정책 연구

박민재,박동호 한국신뢰성학회 2018 신뢰성응용연구 Vol.18 No.4

Purpose: The purpose of this research is to develop a maintenance cost model which is applicable for Korean Lemon Law and to optimize relevant decision variables such as length of warranty period and imposed warranty premium price for the vehicles. Methods: We propose a two-dimensional warranty policy based on age and usage from the manufacturer’s perspective which can be implemented to reduce the warranty cost of a repairable product incurred during the warranty period. We consider both minimal repair service and refund offered under the two-dimensional warranty services. The numerical application is implemented using the proposed approach. Results: This paper shows that when the threshold for the critical component failure increases, the expected cost rate increases while the optimal length of warranty period decreases. On the contrary, when the threshold for the noncritical component failure increases, the expected cost rate decreases while the optimal length of warranty period decreases. Conclusion: We find the optimal length of warranty period which could be very helpful for the business managers to make an appropriate decision for the manufacturer to minimize the total warranty cost and to maximize the customer’s satisfaction.

Extended Weibull power series class with vtub-shaped failure rate for reliability application

박민재 한국신뢰성학회 2019 한국신뢰성학회 학술대회논문집 Vol.2019 No.5

Monte-Carlo simulation of TRIAD

박민재,이재성,박광석 대한핵의학회 2007 핵의학 분자영상 Vol.41 No.5

Two-dimensional warranty for items with preventive maintenance based on Korean Lemon Law

박민재,정기문,박동호 한국신뢰성학회 2018 한국신뢰성학회 학술대회논문집 Vol.2018 No.10

In this paper, we develop a cost model under two-dimensional warranty with age and usage based on Korean Lemon Law and determine decision variables such as optimal preventive maintenance cycle for age and usage perspectives and optimal length of warranty period. We propose a two-dimensional maintenance strategy, under which the item is preventively maintained according to a specified age interval or usage interval, whichever occurs first. A periodic preventive maintenance service is considered which can be implemented to reduce the repair cost of a repairable product under warranty. The optimization of imperfect preventive maintenance for repairable items is investigated from the manufacturer’s perspective by taking into account the moments of customers purchasing two-dimensional warranty. During the warranty period, preventive maintenance service and refund service is conducted to reduce the degradation rate which the product is in operation and to increase customers’ satisfaction. We consider minimal repair service, refund service, preventive maintenance service for the warranty services. The numerical application is implemented using the proposed approach and examples are discussed to exemplify the applicability of the methodologies derived in this paper.

가동률과 비용을 고려한 최적 점검주기 연구

박민재,정기문,박동호 한국신뢰성학회 2021 한국신뢰성학회 학술대회논문집 Vol.2021 No.6

고온에 노출된 PCM 충진형 바닥 시스템의 거동 특성

박민재,민정기,윤성원,주영규 한국공간구조학회 2017 한국공간구조학회지 Vol.17 No.2

Composite Floor system infilled with PCM(Phase Change Material) between upper and lower steel plates was developed to apply the steel frame. When steel frames were applied this system, it can absolutely reduce the duration of construction due to dry construction method. However to apply this system as a structural floor member without fire resistance covering, it must have 2 hours fire resistance performance. Because PCM consisted of three quarters of section with thermal insulation performance, fire resistance performance of this floor system was expected to easily have 2 hours fire resistance performance. This paper was to investigate behavior characteristics of PCM infilled floor system at elevated temperature using FEM analysis to develop the fire resistance performance of it.

ICP-MS를 이용한 사료 내 중금속 분석방법 개발

박민재,김주양,정재학,안장혁,장은희,김효영 한국분석과학회 2023 학술대회논문집 Vol.2023 No.5

Validation of a GATE Model for the Simulation of a Trionix TRIAD SPECT Camera

박민재,Kwang-Suk Park,이재성,Yu-Kyeong Kim,Dong-Soo Lee 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2

The aim of this study was to validate a GATE simulation for the Trionix TRIAD triple head SPECT camera. Experimental and simulated physical characteristics, such as the energy spectrum and resolution, the system sensitivity, and the spatial resolution, were compared. The energy spectrum of the TRIAD was analyzed by using averaged screen-captures of the screen out MCA window and a linear interpolation of the graph. The energy resolution of 140 keV gamma rays was measured without the collimator. To measure the system sensitivity, we measured counts from a Tc-99m point source five times and averaged the results. The spatial resolution was measured from the profile of the line source aligned along the x-axis by using the bi-linear interpolation method. The tests were performed at various distances with a LEUHR parallel-hole collimator for further research on brain scans. The energy window was set to 126 ~ 154 keV for the simulation and to 140 keV ± 20% for the real detector. The shapes of the normalized energy spectra were identical. The energy resolution was 10.1% in the experiment and 9.9% in the simulation, for a 10.1% resolution setting. The sensitivities at various distances (5 cm, 10 cm, 15 cm, and 20 cm) were almost identical. Simulation results (66 counts/sec/MBq) were higher than real experiment results (63 counts/sec/MBq). The spatial resolutions of the simulation data (4.7, 6.3, 7.9, and 9.7 mm) were also comparable to those of real experiments (4.4, 5.8, 7.5, and 9.1 mm). Overall the comparisons showed good agreements between the experimental and the simulation studies. The error levels were roughly 5%, what would be small enough to use the GATE simulation for further MonteCarlo-simulation-based investigations.

서비스 제공 채널의 확장과 채널 간 경쟁적 협력 관계: 게임 산업 사례

박민재 한국품질경영학회 2022 한국품질경영학회 학술대회 Vol.2022 No.1

본 연구는 게임 산업의 채널 확장에서 벌어지는 카니발라이제이션 현상에 대해 발생 여부와 그 정도를 분석하는 것을 목적으로 한다. 본 연구에서는 경쟁관계에 놓여있는 PC 기반의 MMORPG온라인 게임과 모바일 게임 간의 상승 및 쇠퇴의 과정을 두 채널 사이의 상호작용을 통하여 설명하고자 한다. 이를 위하여 본 연구에서는 생태계 시스템에서 상호 경쟁관계에 놓여있는 종족들 사이에서 발생할 수 있는 적자생존, 피식자-포식자 간의 관계를 설명하기 위한 모형으로 Lotka-Volterra 모형을 활용한다. Lotka-Volterra 모형이란 생태계에 서식하고 있는 여러 종 가운데 두 개의 종을 선택하여 한 종은 피식자로 보고 다른 한 종은 포식자로 고려한다. 이 두 종의 생성과 소멸의 과정을 간단한 수리적 모형을 가지고 설명하고자 하는 모형이다. 본 연구에서는 the basic univariate Bass model을 일반화하는 관점을 적용했으며, 이를 바탕으로 Lotka-Volterra model with asymmetric competition (LVac)라는 bivariate life cycle model for competing products 상황의 제품 확산에 적용할 수 있는 혁신 확산 모델을 제안한다. 본 논문에서는 PC 기반 온라인 게임과 모바일 게임 간의 채널 상호 작용과 매출 잠식 현상을 설명하기 위해 LVac 모델을 제안한다. 기존의 the basic univariate Bass model을 카니발라이제션의 존재를 확인하는데 한계가 있다. 두 채널 사이의 상호 작용을 포착하는 것은 각 채널의 수명 주기에 대한 더 나은 설명을 가능하게 할 뿐만 아니라 혁신 확산의 미래 예측 패턴을 더 효율적으로 예측하는 것을 가능하게 한다. 본 연구를 통해 채널의 확정이 “경쟁적 협력 관계(Coopetition)”를 통해 발전해 나간다는 것을 확인한다.