• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2000년도 춘계학술대회 학술발표 논문집
• /
• pp.264-267
• /
• 2000

The need for including time variables in various type of modeled Discrete Event Dynamic Systems(DEDSs) is apparent since the modeled systems are real time in nature. In the real world, almost all event is related to time. A Time Petri Net(TPN) is one of methods for model ins and analyzing of DEDSs with real time values. Two time values, ${\alpha}$$\sub$i/ and ${\beta}$$\sub$i/ are defined for each transition. In this paper, Ire present Fuzzy Transition Timed Petri Net(FTTPN) to determine the optimal transition firing time between ${\alpha}$$\sub$i/ and ${\beta}$$\sub$i/ using fuzzy theory. The traffic signal controller in an intersection is modeled and analyzed by FTTPN.

• Bulletin of the Korean Chemical Society
• /
• 제17권2호
• /
• pp.131-138
• /
• 1996

The conformational transition of oligopeptide multimer,-(HPPHPPP)n-, is studied (H:hydrophobic amino acid, P:hydrophilic amino acid). The helix/coil transitions are detected in the multimer. The transition depends on the number of amino acid in the sequence, the concentration of the oligopeptide, and temperature which affects helix stability constant (${\xi}$) and hydrophobic interaction parameter (wj). In the thermodynamic equilibrium system jA${\rightarrow}$Aj (where A stands for oligopeptide monomer), Skolnick et al., explained helix/coil transition of dimer by the matrix method using Zimm-Bragg parameters ${\xi}$ and $\sigma$ (helix initiation constant). But the matrix method do not fully explain dangling H-bond effects which are important in oligopeptide systems. In this study we propose a general theory of conformational transitions of oligopeptides in which dimer, trimer, or higher multimer coexists. The partition of trimer is derived by using zipper model which account for dangling H-bond effects. The transitions of multimers which have cross-linked S-S bonds or long chains do not occur, because they keep always helical structures. The transitions due to the concentration of the oligopeptides are steeper than those due to the chain length or temperature.

• Bulletin of the Korean Chemical Society
• /
• 제22권7호
• /
• pp.721-726
• /
• 2001

The vibrational transition probability expressions for the forced Morse oscillator have been derived using the commutation relations of the anharmonic Boson operators. The formulation is based on the collinear collision model with the exponential repulsive potential in the framework of semiclassical collision dynamics. The sample calculation results for H2+ He collision system, where the anharmonicity is large, are in excellent agreement with those from an exact, numerical quantum mechanical study by Clark and Dickinson, using the reactance matrix. Our results, however, are markedly different from those of Ree, Kim and Shin's in which they approximate the commutation operator I。 as unity, the harmonic oscillator limit. We have concluded that the quantum number dependence in I。 must be retained to get accurate vibrational transition probabilities for the Morse oscillator.

• 한국해양공학회지
• /
• 제37권3호
• /
• pp.122-128
• /
• 2023

Autonomous berthing is a crucial technology for autonomous ships, requiring optimal trajectory planning to prevent collisions and minimize time and control efforts. This paper presents a two-phase, two-point boundary value problem (TPBVP) strategy for creating an optimal berthing trajectory for a twin-propeller, twin-rudder ship with autonomous berthing capabilities. The process is divided into two phases: the approach and the terminal. Tunnel thruster use is limited during the approach but fully employed during the terminal phase. This strategy permits concurrent optimization of the total trajectory duration, individual phase trajectories, and phase transition time. The efficacy of the proposed method is validated through two simulations. The first explores a scenario with phase transition, and the second generates a trajectory relying solely on the approach phase. The results affirm our algorithm's effectiveness in deciding transition necessity, identifying optimal transition timing, and optimizing the trajectory accordingly. The proposed two-phase TPBVP approach holds significant implications for advancements in autonomous ship navigation, enhancing safety and efficiency in berthing operations.

• Geomechanics and Engineering
• /
• 제21권4호
• /
• pp.349-356
• /
• 2020

Rock brittleness, which is closely related to the failure modes, plays a significant role in the design and construction of many rock engineering applications. However, the brittle-ductile failure transition is mostly ignored by the current statistical damage constitutive model, which may misestimate the failure strength and failure behaviours of intact rock. In this study, a new statistical damage model considering rock brittleness is proposed for brittle to ductile behaviour of rocks using brittleness index (BI). Firstly, the statistical constitutive damage model is reviewed and a new statistical damage model considering failure mode transition is developed by introducing rock brittleness parameter-BI. Then the corresponding damage distribution parameters, shape parameter m and scale parameter F₀, are expressed in terms of BI. The shape parameter m has a positive relationship with BI while the scale parameter F₀ depends on both BI and ε_e. Finally, the robustness and correctness of the proposed damage model is validated using a set of experimental data with various confining pressure.

• 한국유체기계학회 논문집
• /
• 제17권3호
• /
• pp.46-51
• /
• 2014

In this study, a numerical analysis methodology is studied to predict thermal and flow characteristics of C3X vane with internal cooling. Effects of turbulence models, transition models and viscous work term on temperature and pressure distributions on the vane surface are investigated. These optional terms have few effects on the pressure distributions over the vane surface. However, they have great influence on prediction of the temperature distributions on the vane surface. The combination of k-${\omega}$ based SST turbulence model, ${\gamma}$ transition model and viscous work term are better than RSM turbulence model on prediction of the surface temperature. The average temperature difference between CFD results and experimental results is calculated 2 % at the pressure side and 1 % at the suction side. Furthermore computing time of this combination is half of the RSM turbulence model. When k-${\omega}$ based SST turbulence model and ${\gamma}$ transition model with viscous work term are applied, more accurate predictions of thermal and internal flow characteristics of high pressure turbine are expected.

• Journal of Preventive Medicine and Public Health
• /
• 제42권2호
• /
• pp.123-129
• /
• 2009

Objectives : This study aimed to examine the association between public social expenditure(PSE) and suicides in the 27 countries of the Organization for Economic Cooperation and Development(OECD) from 1980 to 2003. Methods : The age-standardized suicide rates and their annual change(%) were obtained from the OECD Health Data 2007. As a measure of social protection, the PSE(% GDP) was used. The covariates included the annual divorce rate(/100,000 population), fertility rate(number of children/woman aged 15 to 49 years), GDP per capita(US$ PPP), male unemployment rate(%), life expectancy(years) and alcohol consumption(liter/capita) for each country, which were all obtained from the OECD Health Data 2007 and the OECD Social Indicators 2006. Using hierarchical linear models that included these covariates, the effects of PSE on suicides(Model 1) and the annual percent change (Model 2) were examined(Model 3). Also, sub-sample analyses were done for six countries that experienced political/economic transition. Results : We could not find significant effects of PSE on suicides(Model 1), but we observed significantly negative effects on the annual percent change for men and women(Model 2). Such findings were replicated in the sub-sample analysis, and moreover, the effect size was much larger(Model 3). Conclusions : Our finding suggests that social welfare protection can be a pivotal factor for suicide epidemiology, and especially in countries experiencing a social crisis or transition.

• Journal of Preventive Medicine and Public Health
• /
• 제36권4호
• /
• pp.377-382
• /
• 2003

Objectives : The purpose of this study was to investigate the predictor associated transitions with each stage of smoking cessation based on the Transtheoretical Model, and to provide basic data for smoking cessation programs for adolescents. Methods : The participants were 297 current and former smokers, obtained from stratified random sampling of 2nd graders from 127 high schools in B cities. The data were collected between April 6th and 16th 2002, using a structured self-report questionnaire, and analyzed using a multiple logistic regression, with the SPSS program for Windows (Version 10.0). Results : The predictors of transition from precontemplation to contemplation were consciousness raising (OR=1.22, 95% CI:1.07-1.40), coping pros (OR=.84, 95% CI:.70-1.00) and attitude of parents to smoking (OR=2.97,95% Cl: 94-9.24). The predictors of transition from contemplation to preparation were helping relationships (OR=.83, 95% CI:.72-.96), self-liberation (OR=1.15, 95% CI: 99-1.33) and nicotine dependence (OR=.76, 95% CI: 56-1.03). The only predictor of transition from preparation to action was the social pros (OR=.66, 95% CI:.57-.82). The predictors of transition from action to maintenance were self-reevaluation (OR=.81, 95% CI:.71-.92) and negative affective situation (OR=.85, 95% CI:.72-1.00). Conclusion : Adequate examination on the factors for predicting the transitional stages of change for smoking cessation in Koreans are presented in this study. The results of this study will become the pillar of smoking cessation Planning and application programs.

• 한국항공우주학회지
• /
• 제42권7호
• /
• pp.535-543
• /
• 2014

비세장형, 둥근 앞전을 가지고 스팬이 1.0m로 축소된 BWB형 UCAV에 대해 완전난류, 천이 모델을 사용하여 전산해석을 수행하였다. 자유류는 받음각 -4도부터 26도까지 50m/s이며, 평균 시위 기준 레이놀즈수는 $1.25{\times}10^6$이다. 멀티블록 6면체 격자와 함께 완전난류 모델과 천이 모델의 결과를 비교하여 천이효과가 공력 특성에 미치는 영향을 살펴보았다. 풍동 실험과 비교한 결과 양/항력 계수는 해석범위 내에서 잘 일치하였으며, 피칭 모멘트는 높은 받음각에서 작게 예측됨과 동시에 난류모델에 따라 결과가 크게 달라졌다. 압력분포와 skin friction line, 축 방향 속도장을 이용하여 와류구조의 거동과 천이현상이 미치는 영향을 살펴본 결과, 천이효과를 고려하는 것이 UCAV의 정확한 와류 구조와 공력특성 예측에 필요한 것으로 확인하였다.

• 한국세라믹학회지
• /
• 제44권1호
• /
• pp.18-22
• /
• 2007

The phase transition behavior of $Ge_2Sb_2Te_5$ (GST) thin film, which is a candidate material of recording layer for phase change random access memory (PRAM), has been evaluated using an in-situ reflectance measurement method. The experimental data have been analyzed by using johnson-mehl-avrami-kolomogorov (JMAK) model. JMAK model can be used only in isothermal state. However, temperature changes with time during the operation of PRAM. To apply JMAK equation to PRAM simulation, it has been assumed that the temperature increases stepwise and isothermally. By using JMAK equation and assumption for the transient state, the phase transition behavior of GST thin film has been predicted under $3^{\circ}C/min$ heating rate in this study. The simulation result agrees well with the experimental results. Therefore, It can be concluded that JMAK equation can be used far the PRAM simulation model.