• The Journal of Korean Society for Radiation Therapy
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• v.23 no.2
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• pp.109-117
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• 2011

Purpose: To analyze the accuracy of tumor volume dose following field width change, to check the difference of dose change by using self-made moving car, and to evaluate practical delivery tumor dose when tomotherapy in the treatment of organ influenced by breathing. Materials and Methods: By using self-made moving car, the difference of longitudinal movement (0.0 cm, 1.0 cm, 1.5 cm, 2.0 cm) was applied and compared calculated dose with measured dose according to change of field width (1.05 cm, 2.50 cm, 5.02 cm) and apprehended margin of error. Then done comparative analysis in degree of photosensitivity of DQA film measured by using Gafchromic EBT film. Dose profile and Gamma histogram were used to measure degree of photosensitivity of DQA film. Results: When field width were 1.05 cm, 2.50 cm, 5.02 cm, margin of error of dose delivery coefficient was -2.00%, -0.39%, -2.55%. In dose profile of Gafchromic EBT film's analysis, the movement of moving car had greater motion toward longitudinal direction and as field width was narrower, big error increased considerably at high dose part compared to calculated dose. The more field width was narrowed, gamma index had a large considerable influence of moving at gamma histogram. Conclusion: We could check the difference of longitudinal dose of moving organ. In order to small field width and minimize organ moving due to breathing, it is thought to be needed to develop breathing control unit and fixation tool.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.14-20
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• 2015

The Korea ministry of land, infrastructure and transport set the goal of cutting greenhouse gas emissions from the transport sector by 34.3% relative to the business as usual scenario by 2020. In order to achieve this goal, support is being given to education and information regarding eco-driving. As a practical measure, however, a vehicle control strategy for decreasing fuel consumptions and emissions is necessary. Therefore, this paper presents an optimized driving model in order to decrease fuel consumption. Scenarios were established by driving mode. The speed profile for each scenario applied to Comprehensive Modal Emission Model and then each fuel consumption was estimated. Scenarios and speed variation with the least fuel consumption were derived by comparing the fuel consumptions of scenarios. The optimized driving model was developed by the derived the results. The speed profiles of general driver were collected by field test. The speed profile of the developed model and the speed profile of general driver were compared and then fuel consumptions for each speed profile were analyzed. The fuel consumptions for optimized driving were decreased by an average of 11.8%.

• Human Ecology Research
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• v.60 no.1
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• pp.53-68
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• 2022

Using a person-centered approach, the current study investigated latent profiles for the emotional and behavioral problems of students in sixth-grade in elementary school and second grade of middle school. The aim was to explore latent transition patterns and verify the factors affecting the transitions. The participants were 1,937 adolescents who responded to the 3^rd year (6^th grade of elementary school; Time 1), 4^th year (1^st grade of middle school), and 5^th year (2^nd grade of middle school; Time 2) of the Korean Children Youth Panel Study. Latent profile and latent transition analyses were performed. The results were as follows: first, the latent profile of emotional and behavioral problems changed from Time 1 to Time 2. The latent groups at Time 1 were classified into low, moderate, high, and externalizing-dominant, whereas at Time 2, five groups were identified: low, moderate, high, externalizing-dominant, and withdrawal-dominant. Second, transition analyses revealed that although 22.3-57.0% of latent groups remained unchanged, there were significant changes over time between groups, as a new group ('withdrawal-dominant') emerged in Time 2. Third, different factors influenced the latent profile transition of emotional and behavioral problems depending on the transition pattern. Higher levels of self-esteem, better relationships with peers and teachers, and lower levels of parental inconsistency meant emotional and behavioral problems had not worsened at Time 2. The results suggest that early interventions are needed during the transition from childhood to early adolescence.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.1
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• pp.68-77
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• 2005

A transient liquid crystal technique has become one of the most effective ways in measuring the local heat transfer coefficients on the entire surface. The key Point of this technique is to convert the inlet flow temperature into an exponential temperature profile using a mesh heater. In order to verify the validity of this technique. the heat transfer characteristics on the wall surface by a pair of longitudinal vortices is investigated experimently and numerically. A standard ${\kappa}-{\varepsilon}$ is used for the numerical analysis of turbulent flow field. It is found from experiment and numerical analysis that two peak values exist over the whole domain. as the longitudinal vortices move to the farther downstream. these peak values decrease and the dimensionless averaged Nusselt number with the lapse of time is maintained nearly at constant values. The experiment results obtained from the present experiment in terms of the transient liquid crystal technique are in good agreement with the numerical results. Therefore, the transient liquid crystal technique developed for the measurement of heat transfer coefficient is proved to be a valid method.

• Structural Engineering and Mechanics
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• v.87 no.2
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• pp.107-116
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• 2023

The three-dimensional Hashin criterion and user subroutine VUMAT were used to simulate the damage in the composite layer, and the secondary stress criterion was used to simulate the interlayer failure of the cohesive element of the bonding layer and the propagation characteristics under the layer. The results showed that when the shear stress wave (shear wave) propagates on the surface of the laminate, the stress wave attenuation along the fiber strength direction is small, and thus producing a large stress profile. When the compressive stress wave (longitudinal wave) is transmitted between the layers, it is reflected immediately instead of being transmitted immediately. This phenomenon occurs only when the energy has accumulated to a certain degree between the layers. The transmission of longitudinal waves is related to the thickness and the layer orientation. Along the symmetry across the thickness direction, the greater is the stress amplitude along the layer direction. Based on the detailed investigation on the impact on various laminated composites carried out in this paper, the propagation characteristics of stress waves, the damage and the destruction of laminates can be explained from the perspective of stress waves and a reasonable layering sequence of the composite can be designed against damage and failure from low velocity impact.

• Progress in Medical Physics
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• v.29 no.1
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• pp.1-7
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• 2018

The $TomoTherapy^{(R)}$ beam-delivery method creates helical beam-junctioning patterns in the dose distribution within the target. In addition, the dose discrepancy results in the particular region where the resonance by pattern of dose delivery occurs owing to the change in the position and shape of internal organs with a patient's respiration during long treatment times. In this study, we evaluated the dose pattern of the longitudinal profile with the change in respiration. The superior-inferior motion signal of the programmable respiratory motion phantom was obtained using AbChes as a four-dimensional computed tomography (4DCT) original moving signal. We delineated virtual targets in the phantom and planned to deliver the prescription dose of 300 cGy using field widths of 1.0 cm, 2.5 cm, and 5.0 cm. An original moving signal was fitted to reflecting the beam delivery time of the $TomoTherapy^{(R)}$. The EBT3 film was inserted into the phantom movement cassette, and static, without the movement and with the original movement, was measured with signal changes of 2.0 s, 4.0 s, and 5.0 s periods, and 2.0 mm and 4.0 mm amplitudes. It was found that a dose fluctuation within ${\pm}4.0%$ occurred in all longitudinal profiles. Compared with the original movement, the region of the gamma index above 1 partially appeared within the target and the border of the target when the period and amplitude were changed. Gamma passing rates were 95.00% or more. However, cases for a 5.0 s period and 4.0 mm amplitude at a field width of 2.5 cm and for 2.0 s and 5.0 s periods at a field width of 5.0 cm have gamma passing rates of 92.73%, 90.31%, 90.31%, and 93.60%. $TomoTherapy^{(R)}$ shows a small difference in dose distribution according to the changes of period and amplitude of respiration. Therefore, to treat a variable respiratory motion region, a margin reflecting the degree of change of respiration signal is required.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1618-1629
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• 2003

The effects of the interaction between flow field and heat transfer caused by the longitudinal vortices are experimentally investigated using a five hole probe and a transient liquid crystal technique. The test facility consists of a wind tunnel with vortex generators protruding from a bottom surface and a mesh heater. In order to control the strength of the longitudinal vortices, the angle of attack of vortex generators used in the present experiment is 20$^{\circ}$, and the spacing between the vortex generators is 25mm. The height and cord length of the vortex generator is 20mm and 50mm, respectively. Three-component mean velocity measurements are made using a f-hole probe system, and the surface temperature distribution is measured by the hue capturing method using a transient liquid crystal technique. The transient liquid crystal technique in measuring heat transfer has become one of the most effective ways in determining the full surface distributions of heat transfer coefficients. The key point of this technique is to convert the inlet flow temperature into an exponential temperature profile using the mesh heater set up in the wind tunnel. The conclusions obtained in the present experiment are as follows: The two maximum heat transfer values exist over the whole domain, and as the longitudinal vortices move to the farther downstream region, these peak values show the decreasing trends. These trends are also observed in the experimental results of other researchers to have used the uniform heat flux method.

• 한국노년학
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• v.40 no.4
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• pp.691-706
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• 2020

This study aims to explore health behavior profiles and the association between the derived profiles and living arrangement among middle-aged and older adults. Using data from wave 6 (2016) of the Korean Longitudinal Study of Aging, latent profile analyses were applied to identify patterns of health behaviors and multinomial logistic regression models were conducted to predict profile membership using living arrangement (i.e., living alone, living with spouse only, living with family members) and sociodemographic characteristics. A sample of 7,048 respondents aged 55 and older were included in the study. Results revealed that Korean middle-aged and older adults can be grouped into four health behavior profiles: "High health-compromising" (4%), "Moderate health-compromising" (28%), "Low health-compromising" (65%), and "High physical activity" (3%). Also, living arrangement showed significant profile differences. Compared to the respondents living alone, those living with spouse only were more likely to belong to low and moderate levels of health-compromising behavior profiles than the "High physicial activity profile". Respondents living with family members were more likely to belong to the "High health-compromising profile" than the "High physical activity profile" compared to those living with spouse only. These findings indicate that living arrangement needs to be taken into consideration when developing health promoting programs and supports. Moreover, policy interventions suiting the needs of various sociodemographic subgroups are recommended.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.187-192
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• 2017

Rigorous longitudinal modal transmission-line theory (L-MTLT) is applied to analyze maximum power transfer in asymmetric grating-assisted directional couplers(A-GADC). By defining a coupling efficiency amenable to rigorous analytical solutions and interference between symmetric and asymmetric supermodes, the power exchange of TE modes as a function of propagation distance is numerically evaluated. The numerical result reveals that maximum power transfer occurs at a grating period ${\Lambda}_{eq}$, in which the insertion loss of supermodes is equal to each other. That is, it is generally different from conventional phase-matching condition of GADC. Furthermore, as the asymmetric profile of grating change to symmetrical profile, the coupling length decreases and the coupling efficiency for power transmission increases.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.195-200
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• 2020

Leakage and Bragg condition of optical waveguides with blazed grating profile are evaluated in detail by using novel and rigorous modal transmission-line theory (MTLT) based on eigenvalue problem. The blazed waveguides classified as symmetric, sawtooth and asymmetric gratings occur leaky-wave stop-band at Bragg conditions and anomalies based on Rayleigh condition near Bragg conditions. Furthermore, DFB properties of blazed waveguides at Bragg conditions are analyzed by applying longitudinal equivalent transmission-line with characteristic impedance of periodic grating. The numerical results show that the reflected power of DFB waveguides is maximized at Bragg conditions in which leaky-wave stop-bands occur.