폭발해석을 위한 간략 폭발하중 제안식

전두진,한상을,Jeon, Doo-Jin,Han, Sang-Eul 한국전산구조공학회 2016 한국전산구조공학회논문집 Vol.29 No.1

본 논문에서는 폭발해석에서 주로 사용되는 폭발하중의 압력-시간 이력곡선과 폭발하중 산정식인 Conwep 모델을 소개하고, 이를 더욱 간편하게 계산할 수 있는 간략 폭발하중 산정식을 제안한다. 폭발해석에서 폭발하중은 일반적으로 압력-시간 이력곡선의 형태로 적용되며, 그에 대한 주요 값들은 폭발하중 산정식에 의해 계산된다. 대부분의 폭발해석에서 사용되는 폭발하중 산정식인 Conwep 모델은 환산거리(scaled distance)를 핵심변수로 하여 계산되는데, 그 계산 과정이 매우 복잡한 단점이 있다. 따라서 본 논문에서는 환산거리를 변수로 갖는 간략한 유리식을 사용하여 주요 값들을 계산하고, 단순화된 압력-시간 이력곡선으로 폭발하중을 산정할 수 있도록 제안하였다. 간략식을 찾는 과정에서 Conwep 모델의 계산 결과를 바탕으로 곡선 적합(curve fitting) 방식이 사용되었으며, 제안된 간략식에 의한 주요 값의 계산 결과는 Conwep 모델과 비교하여 1% 미만의 오차를 갖는다. 또한, 유한요소를 이용한 폭발해석에 적용하였으며 Conwep 모델을 적용한 결과와 비교를 통해 검증하였다. In this paper, a pressure-time history curve of blast load and Conwep model are presented, and a simplified blast load formula is suggested. Generally, a blast load are applied as a pressure-time history curve, and it is calculated by blast load formula such as Conwep model. The Conwep model which is used in most of the blast analysis is quiet difficult to calculate because of its complex process. Therefore, a simplified formula is proposed to calculate blast load by simple rational expressions and to make a simplified pressure-time history curve. In this process, a curve fitting method was used to find the simple rational expressions. The calculation results of the simplified formula have an error of less than 1% in comparison with the Conwep model. And, blast analyses using finite elements method are accomplished with the Conwep model and simplified formula for verification.

Kozak 수간곡선모델을 이용한 우리나라 해안별 곰솔의 수간재적 추정

손영모 ( Son Yeong-mo ),강진택 ( Kang Jin-teak ),전주현 ( Jeon Ju-hyeon ),고치웅 ( Ko Chi-ung ) 한국도서(섬)학회 2017 韓國島嶼硏究 Vol.29 No.4

The stand tree volume table that is currently used was made in 1986 for the first time and there is a gap between the real stand and the previous one. As there is no information on volume(DBH higher than 40cm), it remains as an obstacle in forest management. This study was conducted to estimate optimized stand tree volume table that reflects regional growth performances. Sample trees were selected by diameter from Pinus thunbergi that are distributed along the coastal area in Korea. 340 trees in total were lumbered and their diameter and height were estimated. For the best estimation of stem taper equation, it is conducted by Kozak’s stem taper model(1988). To examinate the fitness, Fitness Index(FI), Bias, Standard Error of Bias(SEE) and Mean Absolute Deviation(MAD) were evaluated. Both the outcomes of each of its volumes compared by coastal area and comparison of volumes between current stem volume table and new stem volume table are as follows. Firstly, for the suitable probation of Kozak stem taper model, fitness index and other tests statistics were compared and analysed. The results showed that it is an appropriate formula when estimating the stem curve of P. thuubergii. Secondly, we have estimated the diameter of stems individually by using Kozak’s stem taper estimation and stem volume as well. To compare the volumes of stem volume table in each coastal area, Duncan’s multiple range test was implemented. The volume in the eastern coast was the biggest followed by the west and southern coast, however, there was no statistically significant difference among these three(p=0.4137>0.05). Therefore, there is no need to adjust volume tables of coastal areas individually. Lastly, the average volume in the current volume table was slightly higher than in the new volume table, however, there was no significant difference between the two(p=0.6558>0.05). To conclude, it is permissible to use the current volume table continuously, but it only shows 40cm of DBH and 30m of tree height. To estimate the volume of P. thunbergii that ranges more than the current stem volume table, it is rather considered to be effective when applied to the new stem volume table(80cm of DBH and 35m of tree height). The new stand volume table of P. thunbergii estimated in this study is expected to be widely utilized for several forest projects such as future forest management plan, permission for forest land use conversion, carbon offset project, collecting basic forest statistics as well as estimation of forestry national greenhouse gas inventory, and so on.

업무혁신 프로그램의 적합도와 관계적 조직문화가 조직몰입에 미치는 영향

한정훈 경성대학교 산업개발연구소 2018 산업혁신연구 Vol.34 No.4

Even though many companies have adopted work-innovation programs recently, there is not much attention to mechanisms that these programs increase workers' commitment to organizations. The purpose of this study is to analyze critical mechanisms regarding program fitness and relational culture that could affect the effect of work-innovation programs on the increase of organizational commitment. From the analysis using latent curve model of 181 companies from 2011 to 2015 in 'Human Capital Corporate Panel(HCCP)' in Korea, the key findings can be summarized into three points. First, if the level of program fitness and relational organization culture was high, workers' commitment to organizations increased, but this effect varied over time. Second, relatively strong effect of relational culture on workers' commitment was observed. Third, the interaction effect of program fitness and relational culture on organizational commitment was positive in the first place, but hardly persisted afterwards. These results can suggest important practical implications. First, while adopting and operating new work-innovation programs, companies should carefully consider programs' fitness and relational culture in organizations. Also, it is necessary to monitor the changing effect of work-innovation programs over time. Especially, the powerful effect of relational culture on workers' commitment to organizations should be recognized and considered as an important organizational condition while adopting and operating new innovational practices. 최근 많은 기업들이 업무혁신을 위한 다양한 프로그램들을 도입하고 있지만 이러한 프로그램들이 근로자의 조직몰입을 높이는 작동기제에 대한 분석은 제한적으로 이루어졌다. 이 연구는 업무혁신 프로그램이 조직몰입을 높이는 중요한 메커니즘으로 프로그램 적합도와 관계적 조직문화의 영향을 확인하는데 목적이 있다. 잠재성장곡선 모형을 통해 인적자원기업패널(HCCP)의 2011년부터 2015년까지 총 181개 기업에 대한 종단분석 결과는 크게 세 가지로 정리된다. 첫째, 혁신 프로그램의 직무적합도와 관계적 조직문화의 수준이 높으면 근로자의 조직몰입이 증가하지만 그 효과는 시간 경과에 따라 달라진다. 둘째, 근로자의 조직몰입에는 상대적으로 관계적 조직문화의 영향이 강하게 나타났다. 셋째, 조직몰입에 대한 프로그램 적합도와 관계적 조직문화의 상호작용 효과는 긍정적으로 나타났지만 그 효과가 시간 경과에 따라 지속되지는 않았다. 이러한 연구결과는 실용적, 정책적 함의를 제공한다. 기업은 업무혁신 프로그램의 도입과 운영에 있어 프로그램의 적합도와 관계적 조직문화의 수준을 면밀하게 고려해야 한다. 또한 시간 경과에 따른 프로그램의 효과 변화를 지속적으로 추적할 필요가 있다. 특히 근로자의 조직몰입에 미치는 관계적 조직문화의 강한 영향력을 인식하고 새로운 제도의 도입과 운영 시 중요한 조직적 조건으로 고려해야 한다.

아스팔트 콘크리트 메스터 곡선에 대한 수정 Ramberg-Osgood 모델 적용

권기철 한국도로학회 2008 한국도로학회논문집 Vol.10 No.4

The dynamic moduli of asphalt concrete are very important for the analysis and the design of asphalt pavement systems. The dynamic modulus master curve is usually represented by a sigmoidal function. The Ramberg-Osgood model was widely used for fitting of normalized modulus reduction curves with strain of soils in soil dynamic fields. The master curves were obtained by both sigmoidal functions and modified Ramberg-Osgood model for the same dynamic modulus data set, the fitting abilities of both methods were excellent. The coefficients in sigmoidal function are coupled. Therefore, it is not possible to separate the characteristics of the master curve with absolute value and shape. However, the each fitting coefficient in the Ramberg-Osgood model has a unique effect on the master curve, and the coefficients are not coupled with each other. The dynamic moduli of asphalt concrete are very important for the analysis and the design of asphalt pavement systems. The dynamic modulus master curve is usually represented by a sigmoidal function. The Ramberg-Osgood model was widely used for fitting of normalized modulus reduction curves with strain of soils in soil dynamic fields. The master curves were obtained by both sigmoidal functions and modified Ramberg-Osgood model for the same dynamic modulus data set, the fitting abilities of both methods were excellent. The coefficients in sigmoidal function are coupled. Therefore, it is not possible to separate the characteristics of the master curve with absolute value and shape. However, the each fitting coefficient in the Ramberg-Osgood model has a unique effect on the master curve, and the coefficients are not coupled with each other.

룰 베이스를 이용한 공조기의 고장검출 및 진단

한도영,주명재 대한설비공학회 2002 설비공학 논문집 Vol.14 No.7

The fault detection and diagnosis (FDD) technology may be applied in order to decrease the energy consumption and the maintenance cost of the air conditioning system. In this study, rule bases and curve fitting models were used to detect faults in an air handling unit. Gradually progressed faults, such as the fan speed degradation, the coil water leakage, the humidifier nozzle clogging, the sensor degradation and the damper stoppage, were applied to the developed FBD system. Simulation results show good detections and diagnoses of these faults. Therefore, this method may be effectively used for the fault detection and diagnosis of the air handling unit.