• Korean Journal of Health Education and Promotion
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• v.29 no.1
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• pp.59-72
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• 2012

Objectives: This study aimed to estimate the trajectory of depressive symptoms among aged 20 years adults and examine the direct and indirect pathway linking socioeconomic status(education attainment, household income, occupation), alcohol use and depressive symptoms. It particularly focused on whether alcohol use would mediate the relationship between socioeconomic status and depressive symptoms. Methods: This study analysed 13,763 households of Korean Welfare Panel Study 1st, 2nd, 3rd data using Latent Growth Curve Modeling. Results: The results showed that study participants tend to decrease depressive symptoms with years. Similar to the findings of the previous studies, education attainment and household income among the socioeconomic status factors effected directly depressive symptoms and indirectly by mediating alcohol volume controlling sex and age. Conclusions: Based on findings of this study, the policy and practical implications were discussed.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.287-288
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• 2015

본 연구에서는 급증하는 청소년기 휴대폰 의존 문제의 심각성에 주목하여 우리나라 청소년들의 휴대폰 의존이 시간의 흐름에 따라 어떠한 변화 양상을 보이는지 실증적인 검증을 실시하고자 하였다. 이를 위하여 한국아동 청소년패널조사(KCYPS) 중학교 1학년 1~4차년도 자료에 대하여 이차잠재성장모형(second-order latent growth modeling)을 이용하여 휴대폰 의존의 발달궤적을 확인하였다. 휴대폰 의존의 발달궤적에 대한 최적의 모형을 찾기 위해 다수의 모형을 구성하여 비교 검증하였으며, 그 결과, 이차함수모형에 대하여 오차 간 공분산을 설정하고, 시간의 흐름에 따른 측정동일성 제약을 가한 후, 오차 간 공분산에 대한 동일화 제약을 가한 모형이 가장 좋은 적합도를 보이는 것으로 확인되었다. 이렇게 도출된 모형에 의하면, 중학교 1학년부터 고등학교 1학년까지 휴대폰 의존 정도는 증가하다가 그 증가율이 둔화되는 이차함수모형의 변화를 보이는 것으로 나타났다. 이러한 결과에 근거하여 청소년기 휴대폰 의존에 대한 예방 및 개입과 관련된 함의를 제시하였다.

• Journal of Environmental Science International
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• v.11 no.10
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• pp.1069-1074
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• 2002

The growth and heavy metal experiments revealed oppositive interactions between toxic metals(Zn and Cd) and Mn when the coastal diatom T. pseudonana were used. Cd and Zn inhibited the algal growth rate only at low Mn ion concentrations and this effect could be accounted for an inhibition of cellular Mn take by the toxic metals. Mn and Zn inhibited cellular Cd take and this indicated a reciprocal effects among the metals with respect to metal take. Saturation kinetics modeling of the take data was consistent with two metals competing with each other for binding to the Mn take system and with both Cd and Mn being transported into the cell by that system. Mathematical modeling of Mn and Cd take data revealed evidence fur a Cd efflux system.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.362-363
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• 2006

Nano-structured tungsten carbide compacts with cobalt matrices (WC-Co) offer new opportunities for achieving superior hardness and toughness combinations. A unified modeling and simulation tool has been developed to produce maps of sintering pathways from nanocrystalline WC powder to sintered nano-structured WC-Co compacts. This tool includes (1) die compaction, (2) grain growth, (3) densification, (4) sensitivity analysis, and (5) optimization. All material parameters were obtained by curve fitting based on results with two WC-Co powders. Critical processing parameters are determined based on sensitivity analysis and are optimized to minimize grain size with high density.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1174-1176
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• 2003

Recently 3D city models are required for many applications such as urban microclimate, transportation navigation, landscape planning and visualization to name a few. The existing 3D city models mostly target on modeling buildings, but vegetation also plays an important role in the urban environment. To represent a more realistic urban environment through the 3D city model, in this research, an investigation is conducted to extract the position of trees from high resolution IKONOS imagery along with Airborne Laser Scanner data. Later, a tree growth model is introduced to simulate the growth of trees in the identified tree-positions.

• Nuclear Engineering and Technology
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• v.46 no.1
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• pp.55-62
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• 2014

A method for estimating software reliability for nuclear safety software is proposed in this paper. This method is based on the software reliability growth model (SRGM), where the behavior of software failure is assumed to follow a non-homogeneous Poisson process. Two types of modeling schemes based on a particular underlying method are proposed in order to more precisely estimate and predict the number of software defects based on very rare software failure data. The Bayesian statistical inference is employed to estimate the model parameters by incorporating software test cases as a covariate into the model. It was identified that these models are capable of reasonably estimating the remaining number of software defects which directly affects the reactor trip functions. The software reliability might be estimated from these modeling equations, and one approach of obtaining software reliability value is proposed in this paper.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.192-200
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• 2021

In the mid of the December 2019, the virus has been started to spread from China namely Corona virus. It causes fatalities globally and WHO has been declared as pandemic in the whole world. There are different methods which can fit such types of values which obtain peak and get flattened by the time. The main aim of the paper is to find the best or nearly appropriate modeling of such data. The three different models has been deployed for the fitting of the data of Coronavirus confirmed patients in Pakistan till the date of 20^th November 2020. In this paper, we have conducted analysis based on data obtained from National Institute of Health (NIH) Islamabad and produced a forecast of COVID-19 confirmed cases as well as the number of deaths and recoveries in Pakistan using the Logistic model, Gompertz model and Auto-Regressive Integrated Moving Average Model (ARIMA) model. The fitted models revealed high exponential growth in the number of confirmed cases, deaths and recoveries in Pakistan.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.181-182
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• 2020

본 연구는 다문화청소년 패널데이터 3차년(2013년)부터 7차년(2017년)까지 패널조사 데이터를 활용하여 다문화청소년의 이중문화수용성이 성취동기에 미치는 영향에 있어 시간의 흐름에 따른 변화를 분석하고자 한다. 이를 위해 잠재성장모형을 이용한 이중문화수용성과 성취동기 간의 상관관계 및 인과적 관계를 규명하는 방법을 적용하였다.

• ETRI Journal
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• v.36 no.3
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• pp.450-459
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• 2014

In this paper, we present a new, easy-to-generate system that is capable of creating virtual 3D tree models and simulating a variety of growth processes of a tree from a single, real tree image. We not only construct various tree models with the same trunk through our proposed digital image matting method and skeleton-based abstraction of branches, but we also animate the visual growth of the constructed 3D tree model through usage of the branch age information combined with a scaling factor. To control the simulation of a tree growth process, we consider tree-growing attributes, such as branching orders, branch width, tree size, and branch self-bending effect, at the same time. Other invisible branches and leaves are automatically attached to the tree by employing parametric branch libraries under the conventional procedural assumption of structure having a local self-similarity. Simulations with a real image confirm that our system makes it possible to achieve realistic tree models and growth processes with ease.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.495-500
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• 2001

The significant creep in copper takes place at relatively low temperature and applied stress. Thus the study on modeling of creep behavior using the copper should provide researchers with benefits such as time for the test. In this study, a test of creep crack growth regarding copper was performed at 400 and $500^{\circ}C$, and analyzed. As result, the crack growth rate at $500^{\circ}C$ turned out to be 10 times higher than that at $400^{\circ}C$ in terms of $C^*$, while the crack growth rate at $500^{\circ}C$ was several hundreds times higher than that at $400^{\circ}C$ in terms of K. Moreover, a linear relationship between the crack growth rate and $C^*$ at the same temperature was established.