• 한국노년학
• /
• v.40 no.1
• /
• pp.91-109
• /
• 2020

This study aims to investigate the interdependence of Korean middle and old-aged couples in the association between exercise and life satisfaction through grip strength trajectory. Data were drawn from the nationally representative Korea Longitudinal Study of Aging (KLoSA) collected from 2006 to 2016. The sample included couples over 45 years of age in the first wave and participated in all six waves of the survey (Ncouple=1,997). There were three steps for analyses: correlation, parallel latent growth curve model, tests of indirect effects of the mediation paths. Covariates included in the models were husbands and wives' characteristics (age, education, work status, chronic diseases, marital satisfaction, contact frequency with friends or neighbors) and couple's household income. Results showed husbands' and wives' life satisfaction and grip strength were interdependent upon each other. Also, exercise participation of both husbands and wives was associated with both husbands' and wives' life satisfaction via the initial level of grip strength of husbands. Moreover, exercise participation of only husbands was associated with wives' life satisfaction through the initial grip strength of husbands. These results suggest the aging processes of middle and old-aged couples need to be understood in the context of gender dynamics and couple interdependence.

• Wind and Structures
• /
• v.35 no.1
• /
• pp.1-20
• /
• 2022

This research work presents an experimental study's outcomes to reveal the impact of an O-ring on the flow control over a sphere placed in a turbulent boundary layer. The investigation is performed quantitatively and qualitatively using particle image velocimetry (PIV) and dye visualization. The sphere model having a diamater of 42.5 mm is located in a turbulent boundary layer flow over a smooth plate for gap ratios of 0≤G/D≤1.5 at Reynolds number of 5 × 10³. Flow characteristics, including patterns of instantaneous vorticity, streaklines, time-averaged streamlines, velocity vectors, velocity fluctuations, Reynolds stress correlations, and turbulence kinetic energy (), are compared and discussed for a naked sphere and spheres having O-rings. The boundary layer velocity gradient and proximity of the sphere to the flat plate profoundly influence the flow dynamics. At proximity ratios of G/D=0.1 and 0.25, a wall jet is formed between lower side of the sphere and flat plate, and velocity fluctuations increase in regions close to the wall. At G/D=0.25, the jet flow also induces local flow separations on the flat plate. At higher proximity ratios, the velocity gradient of the boundary layer causes asymmetries in the mean flow characteristics and turbulence values in the wake region. It is observed that the O-ring with various placement angles (𝜃) on the sphere has a considerable alteration in the flow structure and turbulence statistics on the wake. At lower placement angles, where the O-ring is closer to the forward stagnation point of the sphere, the flow control performance of the O-ring is limited; however, its impact on the flow separation becomes pronounced as it is moved away from the forward stagnation point. At G/D=1.50 for O-ring diameters of 4.7 (2 mm) and 7 (3 mm) percent of the sphere diameter, the -ring exhibits remarkable flow control at 𝜃=50° and 𝜃=55° before laminar flow separation occurrence on the sphere surface, respectively. This conclusion is yielded from narrowed wakes and reductions in turbulence statistics compared to the naked sphere model. The O-ring with a diameter of 3 mm and placement angle of 50° exhibits the most effective flow control. It decreases, in sequence, streamwise velocity fluctuations and length of wake recovery region by 45% and 40%, respectively, which can be evaluated as source of decrement in drag force.

• Journal of Korea Water Resources Association
• /
• v.54 no.spc1
• /
• pp.1167-1181
• /
• 2021

In relation to the algae bloom, four types of blue-green algae that emit toxic substances are designated and managed as harmful Cyanobacteria, and prediction information using a physical model is being also published. However, as algae are living organisms, it is difficult to predict according to physical dynamics, and not easy to consider the effects of numerous factors such as weather, hydraulic, hydrology, and water quality. Therefore, a lot of researches on algal bloom prediction using machine learning have been recently conducted. In this study, the characteristic importance of water quality factors affecting the occurrence of Cyanobacteria harmful algal blooms (CyanoHABs) were analyzed using the random forest (RF) model for Bohyeonsan Dam and Yeongcheon Dam located in Yeongcheon-si, Gyeongsangbuk-do and also predicted the occurrence of harmful blue-green algae using the machine learning and deep learning models and evaluated their accuracy. The water temperature and total nitrogen (T-N) were found to be high in common, and the occurrence prediction of CyanoHABs using artificial neural network (ANN) also predicted the actual values closely, confirming that it can be used for the reservoirs that require the prediction of harmful cyanobacteria for algal management in the future.

• Korean journal of applied entomology
• /
• v.61 no.4
• /
• pp.563-575
• /
• 2022

Maruca vitrata is one of important pests in leguminous crops, especially red bean. We investigated the effects of temperature on development of each life stage, adult longevity and fecundity of M. vitrata for understanding the biological characteristics of the insect species at eight constant temperatures of 13, 16, 19, 22, 25, 28, 31, and 34℃. Eggs hatched successfully at all temperature subjected and larvae successfully developed to the adult stage from 16℃ to 31℃. The developmental period of egg decreased up to 31℃ and after then increased. The developmental period of larva and pupa, and adult longevity of M. vitrata decreased with increasing temperature. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of M. vitrata were estimated by linear regression as 12.8℃ and 280.8DD, respectively. TL and TH from egg hatching to adult emergence using SSI model were 14.2℃ and 31.9℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of M. vitrata was 17.7℃. In addition, we constructed the oviposition models of adult, using the investigated adult traits including survival, longevity, oviposition period and fecundity. Temperature-dependent development models and adult oviposition models will be helpful to understand the population dynamics of M vitrata and to establish the strategy of integrated pest management in legume crops.

• Korean journal of applied entomology
• /
• v.61 no.4
• /
• pp.577-590
• /
• 2022

Ostrinia scapulalis is one of important pests in leguminous crops, especially red bean. In order to understand the biological characteristics of the insect, we investigated the effects of temperature on development of each life stage, adult longevity and fecundity of O. scapulalis at eleven constant temperatures of 7, 10, 13, 16, 19, 22, 25, 28, 31, 34, and 36℃. Eggs and larvae successfully developed next life stage at most temperature subjected except 7, 10 and 13℃. The developmental period of egg, larva and pupa decreased as temperature increased. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of O. scapulalis were estimated by linear regression as 13.5℃ and 384.5DD, respectively. TL and TH from egg hatching to adult emergence using SSI model were 19.4℃ and 39.8℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of O. scapulalis was 20.4℃. Adults produced viable eggs at the temperature range between 16℃ and 34℃, and showed a maximum number, ca. 416 offsprings, at 25℃. Adult models including aging rate, age-specific survival rate, age-specific cumulative oviposition, and temperature-dependent fecundity were constructed, using the temperature-dependent adult traits. Temperature-dependent development models and adult oviposition models will be useful components to understand the population dynamics of O. scapulalis and will be expected using a basic data for establishing the strategy of integrated pest management in leguminous crops.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.36 no.4
• /
• pp.213-220
• /
• 2023

This paper presents a model simulating the folding process and collision dynamics of "ddakji", a traditional Korean game played using paper tiles (which are also referred to as ddakji). The model uses two A4 sheets as the base materials for ddakji. The folding process involves a series of boundary conditions that transform the wing part of the paper structure into a twisted configuration. A rigid plate boundary condition is also adopted for squeezing, establishing the shape and stress state of the game-ready ddakji through dynamic relaxation analysis. The gaming process analysis involves a forced displacement of the striking ddakji to a predetermined collision position. Collision analysis then follows at a given speed, with the objective of overturning the struck ddakji--a winning condition. A genetic algorithm-based optimization analysis identifies the optimal collision conditions that result in the overturning of the struck ddakji. For efficiency, the collision analysis is divided into two stages, with the second stage carried out only if the first stage predicts a possible overturn. The fitness function for the genetic algorithm during the first stage is the direction cosine of the struck ddakji, whereas in the second stage, it is the inverse of the speed, thus targeting the lowest overall collision speed. Consequently, this analysis provides optimal collision conditions for various compression thicknesses.

• Korean Journal of Culture and Social Issue
• /
• v.23 no.4
• /
• pp.527-556
• /
• 2017

The purpose of this study was to examine the effect of group success on organizational commitment in organizational situations. It also aimed to investigate the dynamics in the relevance of motivational attitudes to the individual and group level variables(collective efficacy, group cohesiveness). This study used a multi-level model and tested a series of hypotheses through meso-mediation procedure. The results from 613 naval officials in 36 groups provided evidence that; (1) collective efficacy mediated the relationship between group success and group cohesiveness, (2) the cross-level main effects of group success and collective efficacy were shown on vocationa[l self-efficacy, (3) group cohesiveness exerted positive influence on organizational commitment and (4) the meso-mediation effects among the variables at the multi-level were revealed. It was found that the degree of work motivation and motivational attitudes depended on the group's contextual factors, and that each group's shared perceptions on group performance outcomes could be an important motivational source and cornerstone leading to group cohesiveness. The implications and limitations of these study as well as the direction for future study were discussed.

• Analyses & Alternatives
• /
• v.2 no.2
• /
• pp.111-141
• /
• 2018

By the middle of 2018 there are signs of China's entry into a new period of development, characterized by a change in the old model: "market reforms-inner-party democratization - moderate foreign policy" to another: "market reforms - Xi Jinping personality cult - offensive foreign policy." This model contains the risks of arising of the contradiction between economic freedom and political-ideological rigidity which can lead to destabilization of the political life. However, in the current positive economic dynamics, these risks may come out, rather, in the medium and long term. Today, the political situation in China remains stable - despite growing dissatisfaction in scientific expert and educational circles due to increased control over the intellectual sphere by the authorities. The need for a new redistribution of power between central and provincial authorities could potentially disrupt political stability in the medium term, but, at the moment, is not a critical negative factor. The economic situation is positive-stable. Forecasts indicate a possible increase in China's GDP in 2018 at 6.5%. At the same time, there are negative expectations in connection with the Sino-US and potentially Sino-European "trade war". In the Chinese foreign policy, as a response to Western pressure, China increasingly uses the Russian direction of its diplomacy in the expanded version of Russia + SCO. The nuance here is seen in China's adjusted approach to the SCO: first of all, not as a mechanism for cooperation with Russia, but as an organization that allows using Russia's potential for pressure on the US in the Sino-US strategic rivalry. In the second half of 2018, the Chinese economy will continue to develop steadily, albeit with unresolved traditional problems (debts of provinces and state-owned enterprises, ineffective state sector, risks on the financial and real estate market). In politics, discontent with the cult of Xi will accumulate, but without real threats to its power. Weakening in economic opposition between China and the United States is possible due to Beijing's search for compromises on tariffs, intellectual property, trade deficit. To find such trade-offs, Xi will use the so-called. "Personal diplomacy" of direct contacts with Trump.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.6B
• /
• pp.551-560
• /
• 2009

This paper describes a newly developed pollutant transport model named ARPTM which was designed to simulate the transport and characteristics of pollutant materials after an accidental spill in upstream of river system up to a given position in the downstream. In particular, the ARPTM incorporated ADCP data to compute longitudinal dispersion coefficient and advection velocity which are necessary to apply one-dimensional advection-dispersion equation. ARPTM was built on top of the geographic information system platforms to take advantage of the technology's capabilities to track geo-referenced processes and visualize the simulated results in conjunction with associated geographic layers such as digital maps. The ARPTM computes travel distance, time, and concentration of the pollutant cloud in the given flow path from the river network, after quickly finding path between the spill of the pollutant material and any concerned points in the downstream. ARPTM is closely connected with a recently developed GIS-based Arc River database that stores inputs and outputs of ARPTM. ARPTM thereby assembles measurements, modeling, and cyberinfrastructure components to create a useful cyber-tool for determining and visualizing the dynamics of the clouds of pollutants while dispersing in space and time. ARPTM is expected to be potentially used for building warning system for the transport of pollutant materials in a large basin.

• International Area Studies Review
• /
• v.15 no.1
• /
• pp.495-522
• /
• 2011

In this study, a vector error correction model is considered to analyze the correlations among carbon emission, energy use and economic growth using countries adopted carbon tax such as Finland, Netherland, Newzealand, Sweden, and United Kingdom in the short-run dynamics. In order to examine the effect of a carbon tax on the carbon emission specifically for Finland, New zealand and Sweden in the cointegration coefficients among variables, the economic growth equation has the statistically significant negative value(positive values for Netherland and UK). This implies that in the case of the deviation from a long-run equilibrium all variables except carbon emission and energy use are adjusted toward decreasing. After introducing a carbon tax, all variables for Finland, New zealand and Sweden appear to be negative and positive values for the other countries. The evidence that the carbon emission and energy use have been decreased is very weak in the short-run for Finland, New zealand and Sweden but the economic growth is on the decrease after a carbon tax. However, the empirical results show that the increase in carbon emission leads to the decrease in production for Netherland and UK. This implies that for reducing the carbon emission, these countries need to provide more aggressive policies.