• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1340-1350
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• 1995

The effects of thermal stratification on the flow past a heated circular cylinder with various heating rates were examined in a wind tunnel. Turbulent intensities, r.m.s.values of temperature and turbulent convective heat flux distributions in the cylinder wakes with and without thermal stratification were measured by using a hot-wire and cold-wire combination probe. The phase averaging method was also used to estimate coherent contributions to the turbulent flow field in the near wake. The results show that the scalar mixing process is very different according to the mean temperature fields especially in the upper part of the wake. The coherent structure of the temperature field makes a large contribution to the time mean value like velocity components. However, the coherency of the temperature fluctuation is very different with the change of mean temperature fields, though the velocity coherent motions are quite similar in all experimental conditions.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.87-92
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• 2000

This study is to investigate the heat transfer characteristics the for a round turbulent jet impinging on the flat plate with and without rib. Liquid crystal/transient method was used to determine the Nusselt number distributions along the surface. The temperature on the surface was measured using liquid crystal and a digital color image processing system. The experiments were made fur the jet Reynolds number (Re) 23,000, the dimensionless nozzle-to-surface distance (L/d) from 2 to 10, and the rib type [height ($d_1$) 2mm, pitch (p) from 12 to 36mm]. It was found that for $L/d{\ge}6$ the average Nusselt numbers on the flat plate with rib type C ($p/d_1=16$) are higher than those without rib, mainly due to an increase in the turbulent intensity caused by flow separation, recirculation and reattachment on the wall surface.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.81-91
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• 1994

Combustion noise involved with chemical heat release and turbulent process in turbopropulsion systems, gasturbine, industrial furnaces and internal engines is indeed noisy. The experimental study reported in this paper is made to identify a dominant combustion noise in jet flames. Gaseous propane and kerosene fuel have been used with air as the oxidizer in a different jet combustion systems. Combustion and aerodynamic noise are studied through far field sound pressure measurements in an anechoic chamber. And also mean temperature and velocities and turbulent intensities of both isothermal and reacting flow fields were measured. It is shown that axial mean velocity of reacting flow fields is higher about 1 to 3m/sec than that of cold flow in a gaseous combustor. As the gaseous fuel flow rate increases, the acoustic power increases. But the sound pressure level for the spray flame decreases with increasing equivalence ratio. The influence of temperature in the combustion fields due to chemical heat release has been observed to be a dominant noise source in the spray flame. The spectra of combustion noise in gaseous propane and kerosene jet flame show a predominantly low frequency and a broadband nature as compared with the noise characteristics in an isothermal air jet.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1626-1635
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• 1997

It is important to ensure the reliability of the first localized reactor vessel steel. To satisfy with this purpose, a study on the impact/hardness, low cycle fatigue(LCF), crack growth rate(da/dN) and fracture toughness( ) of base material(BM) and weld metal(WM) were performed under room temperature air and corrosion conditions. A summary of the results is as folows : (1) Charpy impact absorbed energy of BM was the highest value, heat affected zoon(HAZ) and the lowest, WM. The hardness of BM was similar to HAZ. (2) Coefficients of Manson equation using the monotonic tensile test data were obtained for the present material. (3) The effects of stress ratio and ambient (120.deg. C and NaCl) condition on da/dN were investigated, da/dN with NaCl condition expressed the highest value. (4) The results of Charpy V-notch impact test had good correlation with $K_{IC}$ characteristics and the lowest curve of $K_{IC}$ for BM was derived, more researches about WM and HAZ are required hereafter.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.23 no.3
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• pp.78-83
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• 2010

Objectives : The purpose of this study is to compare the principles between moxibustion and the 'Intense pulsed light (IPL)' and to investigate the clinical application of the photo-moxa for the Korean medicine fields. Methods : The characteristics of moxibustion, IPL, parabolic reflector moxa and the dermatology surgical use of moxibustion were reviewed in the literature. Results : IPL is one type of light treatments that is employed by radiating the short-pulse wave, which is transformed from the light of high intensity. There has been used parabolic reflector in Asia for more than 2,000 years, and this hand-held device used for moxibustion in traditional medicine. Moxibustion is one of the treatment tools in Korean medicine using the heat energy. The fluence or energy density of IPL in clinical circumstances is similar to parabolic reflector moxa of moxibustion. IPL and parabolic reflector moxa shared same treatment principle employing the heat energy. Therefore IPL could apply for many indications in Korean medicine as a moxibustion tool and acupuncture. Conclusions: IPL may be plausible to be a fascinate method in phototherapy of Korean medicine.

• The Journal of Korean Physical Therapy
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• v.16 no.2
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• pp.181-194
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• 2004

The aim of this study was to investigate the effects of TENS and cold application on secondary thermal hyperalgesia in rats induced by muscle pain. Muscle pain was induced in male Sprague-Dowley rats by intra-muscular injection of gastrocnemius with $3\%$ carrageenan. The paw withdrawal latency(PWL) and tail flick test(TFT) to heat were used to detect secodary thermal hyperalgesia induced by the muscle pain. PWL and TFT were quantified before and 4, 10, and 24 h after induction of muscle pain and after application of TENS(100Hz, $100{\mu}s$, sensory intensity) and cold($4^{\circ}C$). TENS and cold significantly reduced the PWL and TFT to heat stimuli when compared with controls receiving no TENS and cold(p<.05). These results suggested that application of TENS and cold attributed to decrease secodary thermal hyperalgesia in rat induced by muscle pain.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.1
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• pp.61-70
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• 1992

In this study, corrosion fatigue test of SAPH45 steel was performed by the use of plane bending fatigue tester in marine environment and investigated fracture surface growth behavior of base metal and heat affected zone corrosion fatigue. The main results obtained are as follows: 1) Fracture surface growth of heat affected zone (HAZ) is delayed more than that of base matel (BM), and they tend to faster in seawater than in air. 2) Corrosion sensitivity to corrosion fatigue life of HAZ is more susceptible than that of BM. 3)In the case of the corner crack by corrosion fatigue, the correlation between the propagation rate of fracture surface area(dA/dN) and stress intensity factor range(ΔK) for SAPH45 are applied to Paris rule as follows: dA/dN=C(ΔK) super(m) where m is the slope of the correlation, and is about 6.60-6.95 in air and about 6.33-6.41 in seawater respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1100-1106
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• 2010

LED(Light Emitting Diode) has the defects of low efficiency and reducement of life cycle as its temperature increases. This research is about an efficient temperature control of the LED. For LED temperature control, it is shown that a heat sink, fan, a one-chip microprocessor and the PID control algorithm are a good cooling system through experiments. Finally. by using the fan as a cooling device and controlling it appropriately, it is proved that the intensity of illumination and the desired temperature can be achieved with consumption of only 2% of the driving power of the LED system through control experiments.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.149-156
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• 2006

Structure of edge flame established in a mixing layer, formed between two uniformly flowing pure $CH_4$ and pure $O_2$ streams, is numerically investigated by employing a detailed methane-oxidation mechanism. The numerical results exhibited the most outstanding distinction of using pure oxygen in the fuel-rich premixed-flame front, through which the carbon-containing compound is found to leak mainly in the form of CO instead of HC compounds, contrary to the rich $CH_4-air$ premixed flames in which $CH_4$ as well as $C_2H_m$ leakage can occur. Moreover, while passing through the rich premixed flame, a major route for CO production, in addition to the direct $CH_4$ decomposition, is found to be $C_2H_m$ compound formation followed by their decomposition into CO. Beyond the rich premixed flame front, CO is further oxidized into $CO_2$ in a broad diffusion-flame-like reaction zone located around moderately fuel-rich side of the stoichiometric mixture by the OH radical from the fuel-lean premixed-flame front. Since the secondary CO production through $C_2H_m$ decomposition has a relatively strong reaction intensity, an additional heat-release branch appears and the resulting heat-release profile can no longer be seen as a tribrachial structure.

• Journal of Korean Society of Steel Construction
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• v.8 no.4 s.29
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• pp.133-133
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• 1996

Application of the relationship $da/dN=C({\Delta}K)^{m}$ is effective in the analysis of fatigue crack growth life. The values of material constant C and m have great influences on the predicted fatigue life and the relationship between fatigue crack growth rate(da/dN) and stress intensity factor range(${\Delta}K$) is effective in fatigue crack growth behavior. In this paper, fatigue crack growth behavior of the welded joints in HT60 grade TMCP(Thermo Machanical Control Process) steel have been studied. To evalute the fatigue crack growth rates of HT60 grade TMCP steel, fatigue test was performed by base metal(BM), heat affected zone(HAZ) and weld metal(WM) in TMCP steel at room temperature. We determined the relationship of $da/dN-{\Delta}K$ by correlation between C and m obtained from the Paris-Erdogan power law data supplied HT60 grade TMCP steel. The obtained results from this study indicate that fatigue crack growth rate of TMCP steel is not influenced by softening effect which occurs in the HAZ when high heat input weld is carried out. Softening effects, which affect fatigue properties. are shown that it is not affected to the fatigue growth rates significantly.