• Journal of Advanced Marine Engineering and Technology
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• 제30권1호
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• pp.22-29
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• 2006

Gas turbine engine among Principal internal combustion engines has been mainly applied as an aero and industrial Power plant. In order to increase its thermal efficiency. it has been raised their pressure ratio of compressor and the turbine inlet temperature. To operate above the limit temperature of turbine material, turbine nozzle vanes should be cooled. For this the cooling air is bled from the compressor section of 9as turbine. Meanwhile, to keep high thermal efficiency of 9as turbine, turbine vanes are to be cooled by using small cooling air Therefore, the complex cooling passages are requested to be designed and evaluated the effectiveness of vane cooling by measuring turbine vane temperature. But it is very difficult or impossible for us to measure local turbine temperatures at actual temperature When local heat transfer coefficients are known these can be calculated, therefore this study has been investigated on obtaining these coefficients of turbine vane at room temperature using TLC.

• 한국기계가공학회지
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• 제12권5호
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• pp.9-15
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• 2013

Roll-to-roll printing technology has lately become a subject of special interests in the field of printed electronics. Since this technology has the advantage that continuous and mass production is possible. And for high precision register control is required in multi-layer printing to produce the electronic devices, this is one of the most important technologies in roll-to-roll printing technology. Register error could be generated by various reasons like eccentricity of roll and thermal deformation due to temperature variation in drying section. In this study, the effect of tension variation on the register was analyzed. The results of these analyses show that it is essential to consider the tension disturbance which is generated by the change of temperature in drying section, and conventional register model has limitation to estimate the register error. In order to overcome the limitation of the register model, advanced register model based on the SI process was developed. Also, the performance of the developed model was verified experimentally.

• 동력기계공학회지
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• 제14권2호
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• pp.34-39
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• 2010

Recently, technical trend for machine tools is focused on enhancement of speed and accuracy. High speedy processing causes thermal and structural deformation of objects from the machine tools. Water cooler has to be applied to machine tools to reduce the thermal negative influence with accurate temperature controlling system. Existing On-Off control type can't control temperature accurately because compressor is operated and stopped repeatedly and causes increment of power consumption and decrement of the expected life of compressor. The goal of this study is to minimize temperature error in steady state. In addition, control period of an electronic expansion valve were considered to increment of lifetime of the machine tools and quality of product with a water cooler. PI controller is designed using type of hot-gas bypass for precise control of temperature. Gain of PI is decided easily by method of critical oscillation response, excellent performance of control is shown with 4.24% overshoot and ${\pm}0.2^{\circ}C$error of steady state. Also, error range of temperature is controlled within $0.2^{\circ}C$although disturbance occurs.

• 대한의료기공학회지
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• 제21권1호
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• pp.1-12
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• 2022

Objective : The purpose of this study is to report the results of treating patients with acute low back pain syndrome who are difficult to walk with Whidam's Vibrator Pelvic Sugi Therapy. Methods : We used combinations of korean medicine such as herbal medicine, acupuncture, cupping therapy, and thermal therapy. At the same time, the patient was treated with Whidam's Vibrator Pelvic Sugi Therapy. The first period of hospitalization was 14 days and the second period was 54 days. At the second hospitalization, back pain recurred and was unable to walk. At the first hospitalization, L5-S1 HIVD and L4-5 Mild HIVD were diagnosed on lumbar MRI, and there was no abnormality in blood tests. Results : By relieving muscle tension and restoring the weakened muscle elasticity with herbal treatment and Whidam's Vibrator Pelvic Sugi Therapy, back pain decreased and the inability to walk gradually improved, making it possible to walk on its own. Conclusions : The results of standing and walking on one's own were obtained by relieving muscle tension and restoring weakened muscle elasticity in acute back pain syndrome with gait disturbance diagnosed with lumbar herniated intervertebral disc through korean medicine treatment and Whidam's Vibrator Pelvic Sugi Therapy. Whidam's Vibrator Pelvic Sugi Therapy is thought to help acute back pain by restoring muscle elasticity and strengthening muscle strength. In the future, it is expected that additional clinical studies will be conducted on various pain diseases with Whidam's Vibrator Pelvic Sugi Therapy.

• Earthquakes and Structures
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• 제13권5호
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• pp.429-442
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• 2017

Dry bridges have been widely applied in the Qinghai-Tibet Railway (QTR) to minimize the thermal disturbance of engineering to the permafrost. However, because the Qinghai-Tibet Plateau is an area with a high potential occurrence of earthquakes, seismic action can easily destroy the dry bridges. Therefore, a three-dimensional numerical model, with consideration of the soil-pile interactions, is established to investigate the thermal characteristics and their impact on the seismic response of the dry bridge in permafrost region along the QTR. The numerical results indicate that there exist significant differences in the lateral displacement, shear force, and bending moment of the piles in different thermal conditions under seismic action. When the active layer become from unfrozen to frozen state, the maximum displacement of the bridge pile reduces, and the locations of the zero and peak values of the shear force and bending moment also change. It is found that although the higher stiffness of frozen soil confines the lateral displacement of the pile, compared with unfrozen soil, it has an adverse effect on the earthquake energy dissipation capacity.

• Fibers and Polymers
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• 제2권3호
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• pp.135-140
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• 2001

Organic-inorganic hybrid composites consisting of poly(vinylidene fluoride) (PVDF) and SiO$_2$ were prepared through a sol-gel process and the crystallization behavior of PVDF in the presence of $SiO_2$ networks was investigated by spectroscopic, thermal and x-ray diffraction measurements. The hybrid composites obtained were relatively transparent, and brittleness increased with increasing content of tetraethoxysilane (TEOS). It was regarded from FT-lR and DSC thermal analyses that at least a certain interaction existed between PVDF molecules and the $SiO_2$ networks. X-ray diffraction measurements showed that all of the hybrid samples had a crystal structure of PVDF ${\gamma}$-phase. Fresh gel prepared from the sol-gel reaction showed a very weak x-ray diffraction peak near 2$\theta$=$21^{\circ}$ due to PVDF crystallization, and Intensity increased grade-ally with time after gelation. The crystallization behavior of PVDF was strongly affected by the amount of $SiO_2$ networks. That is, $SiO_2$ content directly influenced preference and disturbance fur crystallization. In polymer-rich hybrids, $SiO_2$ networks had a favorable effect on the extent of PVDF crystallization. In particular, the maximum portent crystallinity of PVDF occurred at the content of 3.7 wt% $SiO_2$ and was higher than that of pure PVDF. However. beyond about 10 wt% $SiO_2$, the crystallization of PVDF was strongly confined.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.1885-1886
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• 2006

The thermal energy from nuclear fission is transferred to the steam generator which is a kind of a large heat exchanger. After the feedwater is injected into the steam generator and absorbs the thermal energy, it is converted into the steam. This steam goes into the turbine. The balance between the generated energy and the consumed energy is required for the nuclear power plant to be stable. For the purpose of which, the feed water, a parameter for energy transfer, should be controlled in stability. Usually, the nuclear power plants are operated in base load in the view of power system for the stability of fission system. Therefore, though there will be almost no unbalance, there can be some instability from unbalance in case of startup/shutdown or disturbance. In this case, the controllability of feedwater pump is very important for the quick recover of stability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.341-344
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• 2002

A matched asymptotic analysis is conducted for a compressible rotating flow in a cylindrical container when a mechanical and/or a thermal disturbance is imposed on the wall. The system Ekman number is assumed to be very small. The conditions for the Taylor-Proudman column in the interior, which were also given in the companion paper Park & Hyun, 2002) by means of the energy balancing analysis, have been re-derived. The concept of the variable, the energy content $e[{\equiv}T+2 {\alpha}^2 {\gamma}{\nu}]$, is reformulated, and its effectiveness in characterizing the energy transport mechanism is delineated. It is seen that, under the condition of the Taylor-Proudman column, numerous admissible theoretical solutions for interior flow exist with an associated wail boundary condition. Some canonical examples are illustrated with comprehensive physical descriptions. The differential heating problem on the top and bottom endwall disks is revisited by using the concept of the energy content. The results are shown to be in line with the previous findings.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권2호
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• pp.187-192
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• 2004

In this paper, we proposed the method to design fuzzy controller using the experience of the operating expert and experimental numeric data for the robust control about the noise and disturbance instead of the traditional PID controller for the main steam temperature control of the thermal power plant. The temperature of main steam temperature process has to be controlled uniformly for the stable electric power output. The process has the problem of the hunting for the cases of various disturbances. In that case, the manual action of the operator happened to be introduced in some cases. We adopted the TSK (Takagi-Sugeno-Kang) model as the fuzzy controller and designed the fuzzy rules using the informations extracted directly from the real plant and various operating condition to solve the above problems and to apply practically. We implemented the real fuzzy controller as the Function Block module in the DCS(Distributed Control System) and evaluated the feasibility through the experimental results of the simulation.

• 한국가시화정보학회지
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• 제19권3호
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• pp.69-76
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• 2021

Printed circuit heat exchanger (PCHE) is a compact heat exchanger with good heat transfer performance, high structure integrity, and reliability over a wide range of temperatures and pressures. Instead of the traditional zigzag and straight shape channel, the sinusoidal shape channel was adopted in this study to investigate the relation of thermal-hydraulic performance and waviness factors (period and amplitude). The local flow characteristics and the heat flux distribution were compared to verify the effects of period and amplitude on heat transfer performance. As the period of channel becomes shorter, the rapid change of the flow direction can produce high flow separation around the corner leading to the disturbance of the boundary layer opposite wall. The nonuniform distribution of flow velocity appeared around the corner positions can promote fluid mixing and lead to higher thermal performance. An evaluation index was used to compare the comprehensive performance of PCHE considering the Nusselt number and Fanning factor. Based on the simulation results, the optimal design parameters of PCHE channel shape were found that the channel with an equivalent bending angle of 15° offers the highest heat flux capacity.