• Steel and Composite Structures
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• 제51권2호
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• pp.139-151
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• 2024

In this research, a semi-analytical solution is presented for computing mechanical displacements and thermal stresses in rotating thick cylindrical pressure vessels made of functionally graded material (FGM). The modulus of elasticity, linear thermal expansion coefficient, and density of the cylinder are assumed to change along the axial direction as a power-law function. It is also assumed that Poisson's ratio and thermal conductivity are constant. This cylinder was subjected to non-uniform internal pressure and thermal loading. Thermal loading varies in two directions. The governing equations are derived by the first-order shear deformation theory (FSDT). Using the multilayer method, a functionally graded (FG) cylinder with variable thickness is divided into n homogenous disks, and n sets of differential equations are obtained. Applying the boundary conditions and continuity conditions between the layers, the solution of this set of equations is obtained. To the best of the researchers' knowledge, in the literature, there is no study carried out bi-directional thermoelastic analysis of clamped-clamped rotating FGM thick-walled cylindrical pressure vessels under variable pressure in the longitudinal direction.

• International Journal of Precision Engineering and Manufacturing
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• 제2권3호
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• pp.61-68
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• 2001

A linear motor has a lot of advantages in comparison with conventional feed mechanisms: high transitional speed, acceleration, high control performance and good positioning at high speed. Through the omission of a power transfer element, the linear motor shows no wear and no backlash, has along lifetime and is easy to assemble. Recently, the two types of linear motors, asynchronous and synchronous linear motors, are often applied to machine tools as a fast feed mechanism. In this paper, a comparison between the two types of linear motors as to power loss and thermal behavior is made. The heat sources of the linear motor-the electrical power loss in the motor and the frictional heat on the linear guidance-are measured and compared. Also, the temperature on the linear motor and machine structure is measured and presented.

• 한국잠사곤충학회지
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• 제40권1호
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• pp.70-77
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• 1998

This study was carried out in order to find out the relationship between physical and chemical properties of silk fiber treated by concentrated calcium nitrate solution. The tensile, thermal and dynamic mechanical properties are also examined on Ca(NO3)2 treated silk fibers. The tensile properties of silk fibers treated by calcium nitrate changed with a concentration. The thermal behavior were also affected by the concentration of calcium nitrate. The degradation temperature (endotherms) and glass transition temperature shifted to lower temperature as the treated concentration increased. It is thought that the physical properties are strongly related to the structure and morphology of Ca(NO3)2 treated silk fibers. As a result, these give property changes with a concentration dependence.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.294-298
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• 2004

Carbon nanotubes(CNTs) were synthesized by thermal chemical vapor deposition(CVD) method. To fabricate CNT gas sensor, catalyst metal layer was deposited on microstructure. The CNT gas detecting layer was grown by thermal CVD method on the catalyst metal layer. In order to investigate the gas sensing characteristics of the fabricated CNT gas sensor, it was exposed in NO$_2$ gas and sensitivity, response, and recovery time were measured. As the result, this sensor has better reproductibility and faster recovery time than another CNT gas sensors.

• 한국생산제조학회지
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• 제24권2호
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• pp.238-243
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• 2015

Recently, the use of assembled-type drills as environmentally friendly products has expanded because the shanks of drills can be reused by replacing the tip when the tools are worn or cut. In addition to their precision and endurable stiffness with respect to the cutting force, assembled-type drills need no stricture because of thermal deformation, which makes replacement easily. In this study, we developed novel assembled-type drills and compared their characteristics, such as the precision, stiffness, and thermal deformation, with those of conventional drills. The new drills exhibited a precision over IT 8 class and no changes in dimensions due to thermal deformation, such that we can change the assembly easily with durability.

• 대한한방체열의학회지
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• 제7권1호
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• pp.44-54
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• 2009

Purpose: To evaluate thermal effect and medication compliance of red ginseng extract. Methods: Randomized, double-blind, placebo-controlled, cross-over clinical study was performed. Twenty four healthy, married women aged 30-45 years with FSFI score below 25 were randomly divided into two groups; red ginseng group(N=12) and placebo group(N=12). During the first 6-week period (Study1), each group was dosed with red ginseng or placebo twice a day. Before starting the second 6-week period(Study2), a crossover design was chosen with a 2-week break(Washout period). Interchanging two groups after Washout period, red ginseng and placebo were dosed to each group. The efficacy of thermal effect was measured with subjective warm sensation scale and lower abdomen temperature by Digital Infrared Thermographic imaging(DITI) before and after each 6-week period. A medication compliance was assessed after each 6-week period and the correlation medication compliance between Sasang Constitution and subjective warm sensation was analyzed. Results: Overall 23 participants completed the study. In subjective warm sensation scale, after taking placebo, all participants exhibited an improving trend, but there was no significant difference. In lower abdomen temperature by DITI, statistically significant objective thermal effect of red ginseng was also not shown. A medication compliance was higher in Yin constitution(Taeumin, Soeumin), and showed an upward trend with decreasing subjective warm sensation. But no statistically significant difference was exhibited. Conclusion: Statistically significant thermal effect of red ginseng was not shown in this study. We anticipate if a long-term clinical trial is practiced, significant thermal effect of red ginseng will be shown.

• 한방안이비인후피부과학회지
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• 제16권2호
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• pp.189-211
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• 2003

The clinical data and thermographic imaging were analyzed on the 38 cases of Bell's palsy who were treated admission in the Oriental Medicine Hospital of Wonkwang University from January 2002 to May 2003. 38 patients with Bell's palsy were within one week after the onset of the paralysis, and thermal type in the DITI were hypo or hyper generally. Nerve conduction test(ENOG and EMG) examined in two weeks after onset. We studied interaction effect between thermal type and paralysis grade on admission day. We studied each main effect ; paralysis grade on admission day - nerve conduction test, nerve conduction test - thermal type, thermal type - paralysis grade after 4 weeks, paralysis grade on admission day - paralysis grade after 4 weeks, sasang constitution - nerve conduction test. The following results were obtained that interaction effect between thermal type and paralysis grade on admission day showed no significance, each main effect ; paralysis grade on admission day - nerve conduction test, paralysis grade on admission day - paralysis grade after 4 weeks, showed significance, each main effect ; nerve conduction test - thermal type, thermal type - paralysis grade after 4 weeks, sasang constitution - nerve conduction test, showed no significance.

• 한국강구조학회 논문집
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• 제10권1호통권34호
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• pp.1-10
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• 1998

교량의 신설 또는 보수를 위한 작업차량의 진출입로나 기존 통행차량의 우회를 목적으로 한시적으로 사용되는 가교량은 일반적으로 상부구조로 H-Beam, 하부구조로 H-Pile을 사용하여, 이들 각 부재를 고장력볼트로 연결한 강구조 형식을 채택하고 있다. 그러나 이러한 교량은 상부구조에 신축이음부를 두지 않고 있어 일일기온차에 의해 발생하는 온도응력이 전체 구조거동에 미치는 영향이 클 것으로 예상된다. 따라서, 본 연구에서는 상부구조인 H-Beam에 온도와 변형률의 상시계측을 위한 모니터링 시스템을 도입하여 측정된 온도 및 변형률 데이터로부터 발생온도와 온도응력의 관계를 조사하였으며, 구조해석을 통한 이론치와의 비교를 실시하여 각 부재에서 발생하는 온도응력이 전체 구조거동에 미치는 영향을 평가하였다. 그 결과, 본 구조물에서 발생하는 응력의 변화는 부재의 온도변화에 의한 온도응력이 주원인인 것으로 나타났으며, 하부구조인 H-Pile의 충분한 교축방향 변위로 인하여 상부구조인 H-Beam의 온도변형 구속은 이루어지지 않는 것으로 나타났다. 한편, 상부구조인 H-Beam간의 연결 강성이 충분하지 않아 전체 구조계보다는 부분 구조계에 대한 해석으로부터 얻어진 변형량이 측정 온도 및 응력으로부터 계산된 변형량과 잘 일치하는 것으로 나타났다.

• 대한한방부인과학회지
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• 제22권3호
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• pp.223-235
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• 2009

Purpose: To evaluate thermal effect and medication compliance of red ginseng extract. Methods: Randomized, double-blind, placebo-controlled, cross-over clinical study was performed. Twenty four healthy, married women aged 30-45 years with FSFI score below 25 were randomly divided into two groups; red ginseng group(N=12) and placebo group(N=12). During the first 6-week period (Study1), each group was dosed with red ginseng or placebo twice a day. Before starting the second 6-week period(Study2), a crossover design was chosen with a 2-week break(Washout period). Interchanging two groups after Washout period, red ginseng and placebo were dosed to each group. The efficacy of thermal effect was measured with subjective warm sensation scale and lower abdomen temperature by Digital Infrared Thermographic imaging(DITI) before and after each 6-week period. A medication compliance was assessed after each 6-week period and the correlation medication compliance between Sasang Constitution and subjective warm sensation was analyzed. Results: Overall 23 participants completed the study. In subjective warm sensation scale, after taking placebo, all participants exhibited an improving trend, but there was no significant difference. In lower abdomen temperature by DITI, statistically significant objective thermal effect of red ginseng was also not shown. A medication compliance was higher in Yin constitution(Taeumin, Soeumin), and showed an upward trend with decreasing subjective warm sensation. But no statistically significant difference was exhibited. Conclusion: Statistically significant thermal effect of red ginseng was not shown in this study. We anticipate if a long-term clinical trial is practiced, significant thermal effect of red ginseng will be shown.

• 한국연소학회지
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• 제12권1호
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• pp.28-37
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• 2007

Numerical study is conducted to grasp the flame structure and NO emissions for a wide range of oxy-fuel combustion (covering from air blown combustion to pure oxygen combustion) and for various mole fractions of recirculated $CO_2$ in $CH4-O_2/N_2/CO_2$ counterflow diffusion flames. Special concern is given to the difference of the flame structure and NO emissions between air blown combustion and oxy-fuel combustion w/o recirculated $CO_2$ and is also focused on chemical effects of recirculated $CO_2$. Air blown combustion and oxy-fuel combustion w/o recirculated $CO_2$ are shown to be considerably different in the flame structure and NO emissions. Modified fuel oxidation reaction pathways in oxygen-enriched combustion are provided in detail compared to those in air blown combustion w/o recirculated $CO_2$. The formation and destruction of NO through Fenimore and thermal mechanisms are also compared for air blown combustion and oxyegn-enriched combustion w/o recirculated $CO_2$, and the role of the recirculated $CO_2$ and its chemical effects are discussed. Importantly contributing reaction steps to the formation and destruction of NO are also estimated in oxygen-enriched combustion in comparison to air blown combustion.