목적 : 본 연구의 목적은 Coronavirys Disease(COVID-19) 팬데믹을 거친 고령자의 사회적 건강의 수준의 변화궤적에 대한 잠재계층을 분류하고 잠재 계층별 특성을 분석함에 있다. 또한 이러한 사회적 건강에 영향을 미치는 예측요인을 파악하여 고령자의 사회적 건강을 증진을 위한 기초자료를 마련하고자 한다. 연구방법 : 국내 고령자의 사회적 친밀도에 따른 사회적 건강 유형을 파악하기 위해서 한국복지패널의 3 년차 종단자료를 토대로 분석하였으며, 연구대상자는 세 시점 모두를 응답한 2845명의 고령자를 대상으 로 하였다. 대상자중심접근인 성장혼합모형(Growth Mixture Model; GMM)을 적용하여 변화궤적에 따 른 잠재계층을 분석 하였고, 도출된 각 잠재유형별 특성을 파악하기 위해 χ2 분석, 분산분석을 실시하 였으며, 계층 간 차이를 유발하는 요인을 파악하기 위해 다항로지스틱 회귀분석을 실시하였다. 결과 : GMM 적용결과, 사회적 건강의 변화궤적에 대한 잠재계층은 최종 4개의 집단으로 저수준 감소-증 가 집단, 중수준 유지-증가 집단, 고수준-감소 집단, 고수준 유지’집단으로 분류되었다. 또한 사회적 건강 수준에 따라 여가만족도에서 차이가 나타나는 것으로 드러났으며, 그 외에도 연령 차이가 존재하였 다. 잠재계층분류에 영향을 미치는 영향변인을 검증한 결과, 특히 여성일수록, 종교를 가지고 있을수록, 여가만족도와 전반적 만족도가 모두 높을수록 고수준 유지 집단에 속할 확률이 높은 것으로 나타났다. 결론 : 국내 고령자의 사회적 건강은 시간이 지남에 따라 감소하는 궤적을 보이는 것으로 나타났다. 변화 궤적에 따라 4개의 집단으로 구분 지을 수 있으며, 각 잠재 유형별 연령과 여가 만족도 부분에서 집단별 차이가 드러났다.

The topic of this study is the field of humanitarian logistics for disaster response. Many existing studies have revealed that compliance with the golden time in response to a disaster determines the success or failure of relief activities, and logistics costs account for 80% of the disaster response cost. Besides, the agility, responsiveness, and effectiveness of the humanitarian logistics system are emphasized in consideration of the disaster situation’s characteristics, such as the urgency of life-saving and rapid environmental changes. In other words, they emphasize the importance of logistics activities in disaster response, which includes the effective and efficient distribution of relief supplies. This study proposes a mathematical model for establishing a transport plan to distribute relief supplies in a disaster situation. To determine vehicles’ route and the amount of relief for cities suffering a disaster, it mainly considers the urgency, effectiveness (restoration rate), and uncertainty in the logistics system. The model is initially developed as a mixed-integer nonlinear programming (MINLP) model containing some nonlinear functions and transform into a Mixed-integer linear programming (MILP) model using a logarithmic transformation and piecewise linear approximation method. Furthermore, a minimax problem is suggested to search for breakpoints and slopes to define a piecewise linear function that minimizes the linear approximation error. A numerical experiment is performed to verify the MILP model, and linear approximation error is also analyzed in the experiment.

PURPOSES : The feasibilities of cohesive elastoplastic contact model and discrete element method (DEM) for asphalt concrete mixture compaction process were evaluated. METHODS : The contact models that were used to simulate the dynamic behavior of construction materials were reviewed. The characteristics of cohesive elastoplastic models were discussed from the perspective of integration with existing contact models. Two asphalt mixtures that were fabricated with specific aggregate gradations and binder contents were compacted according to the Superpave gyratory compaction specification. The parameters for the model were determined via trial-and-error method. The heights of the specimens were plotted with respect to number of gyrations. The results of the laboratory tests were compared to those of numerical simulations. The displacement of particles in asphalt mixture specimen was also visualized to understand the effect of gyratory compaction on asphalt mixture specimen. RESULTS : The DEM model exhibited a significant friction coefficient dependency on compaction degree and slop. The DEM model with parameters determined through trial and error demonstrated reasonable simulation results in terms of specimen height at a gyration number. CONCLUSIONS: Even though a little discrepancy was observed between the results of the experimental test and numerical simulation, a combination of DEM with cohesive elastoplastic contact model seems to be applicable for the simulation of asphalt mixture compaction in laboratory. However, the model needs to be enhanced to be used for more realistic compaction processes, including heat transfer, phase change, and vibratory loading.

Reliability analysis of the components frequently starts with the data that manufacturer provides. If enough failure data are collected from the field operations, the reliability should be recomputed and updated on the basis of the field failure data. However, when the failure time record for a component contains only a few observations, all statistical methodologies are limited. In this case, where the failure records for multiple number of identical components are available, a valid alternative is combining all the data from each component into one data set with enough sample size and utilizing the useful information in the censored data. The ROK Navy has been operating multiple Patrol Killer Guided missiles (PKGs) for several years. The Korea Multi-Function Control Console (KMFCC) is one of key components in PKG combat system. The maintenance record for the KMFCC contains less than ten failure observations and a censored datum. This paper proposes a Bayesian approach with a Dirichlet mixture model to estimate failure time density for KMFCC. Trends test for each component record indicated that null hypothesis, that failure occurrence is renewal process, is not rejected. Since the KMFCCs have been functioning under different operating environment, the failure time distribution may be a composition of a number of unknown distributions, i.e. a mixture distribution, rather than a single distribution. The Dirichlet mixture model was coded as probabilistic programming in Python using PyMC3. Then Markov Chain Monte Carlo (MCMC) sampling technique employed in PyMC3 probabilistically estimated the parameters’ posterior distribution through the Dirichlet mixture model. The simulation results revealed that the mixture models provide superior fits to the combined data set over single models.

The purpose of this study is to investigate the influence of social factors on the use of honorific language by discourse completion test. Participants complete a short discourse by filling in their responses in conversations that may occur in families, schools, and workplaces where the social status and solidarity of the listener is predetermined. Honorific styles of sentence endings of their responses are analyzed by the generalized linear mixed model. The results show that social status and solidarity are statistically significant factors in the use of honorific styles, but their effects are dependent on the discourse situation. The ratio of using honorific styles gradually increases as the formality of situation increases (i.e., family < school < workplace). Interestingly, when the solidarity is low at the workplace, the ratio of using honorific styles is consistently high regardless of the social status of the listener. These results show that the use of Korean honorific styles is pragmatically changing according to the discourse situation.

본 연구에서는 (주)파인텍에서 제조한 제올라이트 4A 분리막을 이용하여 물/메탄올, 물/부탄올 혼합물의 투과증발 실험을 수행하였다. 분리막을 투과한 기체분자들은 액체질소트랩을 이용하여 포집하였으며, 기체크로마토그래피(TCD)를 이 용하여 혼합물의 조성을 분석하였다. 실험을 통해 물과 메탄올(분리계수 최대 250 이상), 물과 부탄올(분리계수 최대 1,500 이상)의 혼합물에서 선택적으로 물을 분리하는 것을 확인하였다. GMS (generalized Maxwell Stefan) 이론을 적용하여 2성분 계의 투과증발 거동을 모사하였으며, 상수추정을 통하여 제올라이트 비지지체의 흡착상수 및 확산상수를 구하였다. 제올라이 트 4A 분리막의 경우 기공의 크기가 물보다는 크고, 메탄올, 부탄올 보다는 작기 때문에, 알코올로부터 물을 분리시키는 공정 에 적용시킬 수 있다. 바이오 에탄올 분리, 부탄올 분리, 막반응기, 하이브리드 반응-탈수 공정 등에 적용할 수 있을 것으로 사료된다.

The rapid growth of engineering technology and the emergence of systemized and large-scale engineering systems have resulted in complexity and uncertainty throughout the lifecycle activities of engineering systems. This complex and large-scale engineering system consists of numerous components, but system failure can be caused by failure of any one of a number of components. There is a real difficulty in managing such a complex and large-scale system as a part. In order to efficiently manage the system and have high reliability, it is necessary to structure a system with a complex structure as a sub-system. Also, in the case of a system in which cause of failures exist at the same time, it is required to identify the correlation of the components lifetime and utilize it for the design policy or maintenance activities of the system. Competitive risk theory has been used as a theory based on this concept. In this study, we apply the competitive risk theory to the models with combined structure of series and parallel which is the basic structure of most complex engineering systems. We construct a competing risks model and propose a mathematical model of net lifetime and crude lifetime for each cause of failure, assuming that the components consisting a parallel system are mutually dependent. In addition, based on the constructed model, the correlation of cause of failure is mathematically analyzed and the hazard function is derived by dividing into net lifetime and crude lifetime.

아스팔트 혼합물은 플랜트에서 가열, 이송, 혼합, 배출 등의 여러 가지 공정을 거쳐 생산되며, 생산된 아스팔트 혼합물은 현장으로 이송되어 포설 및 다짐의 과정을 거쳐 아스팔트 포장으로 적용된다. 이와 같 이 다양한 외부 환경에 노출된 아스팔트 혼합물의 생산 및 적용 공정은 최종 생산품이 실내에서 완성되어 재료의 균질성이 확보되는 일반적인 산업분야와는 확연히 다른데, 이러한 요인에 의하여 아스팔트 혼합물 의 생산 및 포설, 다짐 공정을 현장에서 정량적으로 모니터링하고 개선하여 재료의 잠재적인 성능을 최대 한 활용하는데 한계가 있다. 이와 같은 한계를 극복하기 위한 대안을 제시하기 위한 방법으로는 재료의 동적 거동 및 여건을 모사할 수 있는 이산요소법(Discrete Element Method, DEM)을 고려할 수 있다. 재 료가 다른 재료와 접촉할 때의 부착을 포함한 동적 거동의 특성은 이산요소법에서 접촉모형(Contact Model)을 이용하여 표현되는데, 아스팔트 혼합물과 같이 혼합재료의 가시적 구분이 가능한 재료의 생산 및 포설, 다짐까지의 공정을 모두 모니터링 하여 재료의 성능을 확보하기 위해서는 시간 또는 온도 변화 에 따른 굵은 골재, 잔골재, 아스팔트 바인더의 물성 등 개별요소의 물성을 각각 측정하여 혼합물 전체의 성능을 예측하는, 실용적 측면에서의 다상 모사(Multiphase Simulation) 기법에 적용하기 쉬운 접촉모형 을 결정하는 것이 합리적이다. 이러한 기법을 활용하면 생산과 포설 단계에서의 도로포장 재료의 동적 거 동을 분석하여 시설 및 과정을 최적화 할 수 있을 뿐만 아니라, 이미 포설되어 차량이 운행 중인 도로의 파손에 대한 초기 생산 조건의 영향을 확인할 수 있기 때문이다. 따라서 본 연구에서는 골재의 탄성계수와 바인더의 시간 및 온도 종속적인 부착성 점소탄성 특성을 반 영할 수 있는 정교한 접촉모형을 개발을 위하여, 해석적 방법으로 정해가 유도될 수 있는 비교적 단순한 점탄성 모형과 선형 부착모형을 이산요소법의 부착모형으로 개발 및 적용하고 이에 대한 가능성을 검증하 고자 하였다.

An algebraic model for turbulent heat fluxes is proposed on the basis of the elliptic blending equation. The algebraic model satisfies the temperature-pressure gradient correlation characteristics of near-wall region and the flow center region far away from the wall. That is, the turbulent heat flux conditions for both regions are connected by the solution of the elliptic blending equation. The predictions of turbulent heat transfer in a plane channel flow have been carried out with constant wall heat flux and constant wall temperature difference boundary conditions respectively. Also, the rotating channel flow with constant wall temperature difference is considered to test the applicability of the model. The prediction results show that the distributions of the turbulent heat fluxes and mean temperature are well captured by the present algebraic heat flux model.

This study describes the amendment of Durbin's k-∈-v2-f model and its application to turbulent channel flow to test the model’s performance. Modeling redistribution and dissipation rate terms for the scalar v2 transport equation is considered by the elliptic blending equation which is used in the second moment closure generally. The prediction results are directly compared to the DNS and Durbin's original k-∈-v2-f model to assess the performance of the new model predictions and to show their reasonable agreement with the DNS and Durbin's model for all the flow characteristics that are analyzed for the present study.

Previous researches have focused on the efficiency of project execution and the satisfaction of internal customers in view of the fact that a project is successful if any defects are not found in the short-term performance test of the project final outcom

The paper reviews gauge R&R studies by two-factor mixed models including random and fixed factors. The two-factor mixed models include restricted models and unrestricted models considering the interaction of two factors. This study also classifies the models according to the number of factors, and the combination of various factors such as random factor, fixed factor, block factor and repetition type.

The research contributes extending and reviewing of restricted (constrained) and unrestricted (unconstrained) models in GLM(Generalized Linear Models). The paper includes the methodology for finding EMS(Expected Mean Square) and F0 ratio. The results can be applied to the gauge R&R(Reproducibility and Repeatability) in MSA(Measurement System Analysis).

포장 공용성 모델은 역학적-경험적 포장설계법에서 포장의 수명을 결정하기 위한 가장 중요한 인자이다. 한국 포장연구 프로그램의 일환으로 한국형 포장설계법이 역학적-경험적 방법에 근거하여 현재 개발중에 있다. 본 연구에서는 포장 공용성모델중 아스팔트 혼합물의 영구변형 예측모델을 삼축압축 반복재하시험을 이용하여 개발하였다. 본 시험은 다양한 아스팔트 혼합물에 대하여 온도와 공극률을 변화시켜 하중재하 횟수에 따른 혼합물의 영구변형 특성을 조사하였으며, 본 시험결과를 이용하여 예측모델의 계수값을 결정하였다. 영구변형 예측모델의 계수값은 포장가속시험결과를 토대로 다양한 혼합물에 대한 시험결과를 이용하여 깊이에 따른 전단응력의 변화를 고려한 통합적인 소성변형 모델계수값을 정하는 것보다 혼합물의 종류에 따른 모델계수를 산정하는 것이 보다 정확한 결과를 예측할 것으로 판단된다.

We consider a mixed model with covariates considered as fixed effects and a random factor. In this paper, we consider methods for constructing confidence intervals on measures of variability in repeatability and reproducibility study to the mixed model with fixed effects and random effects. Computer simulation is used to determine how well confidence intervals maintain the stated confidence level and compare confidence interval lengths for the methods. A numerical example is considered to illustrate the confidence intervals proposed.