• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.709-715
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• 2015

Underwater gliders do not typically have separate propellers for forward motion. They generate propulsive forces based on the difference between their buoyancy and gravity. They can control the volume from the buoyancy engine to adjust the propulsive force. In addition, the attitude of the underwater glider is controlled by a rubberless motion controller. The motion controller can change the mass center and moment of inertia of the inner moving mass. Owing to the change in these parameters, the attitude of the underwater glider is changed. In this study, we derive nonlinear, six degree of freedom (DOF) mathematical models for the motion controller and buoyancy engine. Using these equations, we perform dynamic simulations of the proposed underwater glider, and verify the suitability of the design and dynamic performances of the proposed underwater glider. We then perform the motion control simulation for the pitch and roll angle, and analyze the dynamic performance according to the pitch and roll angles.

• Resources Recycling
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• v.32 no.6
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• pp.25-33
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• 2023

With the growth of the battery industry, a rapid increase in the production and usage of lithium-ion batteries is expected, and in line with this, much interest and effort is being paid to recycle waste batteries, including production scrap. Although much effort has been made to recycle cathode material, much attention has begun to recycle anode material to secure the supply chain of critical minerals and improve recycling rates. The proximate analysis that measures the content of coal can be used to analyze graphite in anode material, but it cannot accurately analyze due to the interaction between the components of the black mass. Therefore, in this study, thermogravimetric analysis of each component of black mass was measured as the temperature increased up to 950℃ in an oxygen atmosphere. As a result, in the case of cathode material, no change in mass was measured other than a mass reduction of about 5% due to oxidation of the binder and conductive material. In the case of anode material, except for a mass reduction of about 2% due to the binder, all mass reduction were due to the graphite(fixed carbon). In addition, metal conductors (Al, Cu) were oxidized and their mass increased as the temperature increased. Thermal analysis results of mixed samples of cathode/anode show similar results to the predictive values that can be calculated through each cathode and anode analysis results.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.24-29
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• 1998

An experimental study was carried out to investigate the characteristics of spray pattern such as discharge coefficient, spray angle, and mass distribution for two-fluid airblast swirl injector, within the range of fluid supply pressure 0~13kg/$\textrm{cm}^2$. In general atomization is promoted with increasing total gas mass flow and performance of the splay pattern was more stable when radial mass flow was greater than axial mass flow, radial swirler was better than Axial swirler for atomization. Equivalent spray angle did not change with water mass flow except for the condition of 3kg/$\textrm{cm}^2$ and showed the same for the gas mass flow. Mass distribution from the patternator shows that maximum value of the distribution were lowered but distributed larger area when gas flow rate increased. Center of mass position did not change with increasing water mass flow.

• Journal of Energy Engineering
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• v.14 no.4 s.44
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• pp.213-218
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• 2005

In order to understand the heat and mass transfer characteristics of humid airflow in frosting conditions, a flat plate of aluminum with cooling modules located in the central part of the plate was used. A microscope system (resolution of 0.05 mm) was used for the measurement of local thickness of frost at seven points along the plate in the flow direction. For the total mass of frost at each test operation, an electronic balance (resolution of 1 mg) was used. The local frost thickness distributions far various test conditions were presented along with the frost mass data measured at the given operating times. The effect of humidity and velocity of humid air on frosting were analyzed.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.586-594
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• 2011

Gravity Recovery and Climate Experiment (GRACE), launched in April, 2002, makes it possible to monitor Earth's mass redistribution with its time-varying gravity observation. GRACE provides monthly gravity solutions as coefficients of spherical harmonics, and thus ones need to convert the gravity spectrum to gravity grids (or mass grids) via the spherical harmonics. GRACE gravity solutions, however, include spatial alias error as well as noise, which requires to suppress in order to enhance signal to noise ratio. In this study, we present the GRACE data processing procedures and introduce some applications of time-varying gravity, which are studies of terrestrial water storage changes, Antarctic and Greenland ice melting, and sea level rise. Satellite missions such as GRACE will continue up to early 2020, and they are expected to be an essential resource to understand the global climate changes.

• The Journal of Internal Korean Medicine
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• v.35 no.4
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• pp.448-454
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• 2014

Objectives: The aim of this study was to analyze the change of lateral shift of Center of Pressure (CoP) according to the gait improvement in post-stroke hemiplegic patients and to investigate relationship between the change of motor grade and lateral shift of CoP. Methods: We measured the lateral shift of CoP and motor grade of eight post-stroke hemiplegic patients at the beginning of dependent gait and independent gait. Results: We found that CoP tended to be shifted to the non-affected side when patients started to walk independently. Furthermore, there was no relationship between the change of motor grade and lateral shift of CoP. Conclusions: This result may suggest it is more important to control the non-affected side than the affected side, at least until the beginning independent gait.

• Journal of Families and Better Life
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• v.27 no.6
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• pp.1-12
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• 2009

The purpose of the study is to investigate developmental changes in the effect of sociocultural factors towards appearance, body mass index and self-esteem on body image. Participants were 315elementary school, 305middle school students, 310hight school students and 346college students from Seoul and Gyeonggi Province. Collected data were analyzed through Cronbach's $\alpha$, Two-way ANOVA, Pearson's correlation, and stepwise multiple regression. The findings of the study were as follows: 1) Sociocultural factors towards appearance, body mass index, self-esteem and body image differed by grade and gender. 2) Peers, self-esteem, BMI and mass media were significant predictors of elementary school students' body image. Mass media, BMI and self-esteem were significant predictors of middle school students' body image. Self-esteem, peers, BMI, gender and mass media were significant predictors of high school students' body image. Self-esteem, mass media and BMI were significant predictors of college students' body image.

• Journal of the Korean Society of Costume
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• v.66 no.8
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• pp.33-45
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• 2016

This study classified respondents by degree of obesity using Body Mass Index(BMI) and investigated the differences in self-esteem, food lifestyle, social-cultural attitudes towards appearance, and diet-related attitude and behavior such as trial number of diet, exercise time and period, use of diet information, interest in weight control, diet motivation, and dietetic therapy. A survey was conducted with 258 adults between the ages of 20 and 29 who lived in Daegu and Uijeongbu from November $17^{th}$ to December $14^{th}$ 2014. Data collected from the respondents were analyzed using descriptive statistics, factor analyses, analyses of variance and chi-square tests. This study divided the respondents into three groups (the underweight, the normal weight, the overweight) according to Body Mass Index. The results showed that there were significant differences in food lifestyle (health-conscious, popularity-seeking, taste-seeking), social-cultural attitudes towards appearance, exercise time and period, use of diet information, interest in weight control, diet motivation, and dietetic therapy among groups classified by degree of obesity. However, there were no differences in self-esteem, convenience-seeking, and trial number of diet among them.

• Journal of Astronomy and Space Sciences
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• v.10 no.2
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• pp.163-188
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• 1993

On the framework of Tolman spacetime model, the caustics around a local perturbed region in redshift is due to the local expansion rate induced by a local density inhomogeneity in real space. We have compared the caustics in redshift space, which are analytically obtained, with the observed redshift-distance patterns of galaxies which are belonging to Coma and Perseus clusters. For the Abell density distribution model and polytropic density profiles which are well-fitting the optical and X-ray observations, respectively, the size of caustics which is defined by "turnaround radius" of a local density perturbed region should give constraints on the sizes and masses of rich clusters and give also a clue to understand the state of hot X-ray emitting gas.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.132-137
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• 2017

This paper proposes a transformation method of the zero moment point (ZMP) and the center of mass (CoM) from one walking pattern to other patterns by considering the structure of a robot or walking situations in real time. In general, a humanoid robot has own structure characteristics like height and mass. The structure characteristics make the given CoM/ZMP walking pattern of one human or one humanoid robot to be difficult to apply to other robot directly. For this purpose, we analyze the characteristics of walking patterns according to the step length, duration of walking support phase and the CoM height by using the cart-table model as the simple humanoid robot model. A transformation equation is derived from the analyzation and it is verified with simulation.