• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.6 s.261
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• pp.539-546
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• 2007

An experimental study was performed to investigate the characteristics of chemiluminescence in a radiant burner, varying the excess air ratio from 0.91 to 1.67 at firing rate 80.5 to 134.2 kW/m2 on $OH^*,\;CH^*,\;{C_2}^*$ in LNG-Air premixed flames. The signals from electronically excited states of $OH^*,\;CH^*,\;{C_2}^*$ were detected using a Intensified Couple Charged Detector (ICCD) camera. The measurements of exhausted emission were made to investigate the correlation between chemiluminescence and emissions. The chemiluminescence intensity was increased with increase of firing rate like characteristics of $NO_x$ emission. $NO_x$ also increased with increase of firing rate and excess air ratio. It is found that offset of firing rate is more dominant excess air ratio $NO_x$ emission. The maximum chemiluminescence intensity occurs near the stoichiometric excess air ratio or lean conditions in case of high firing rate and the maximum intensity occurs rather than rich conditions in case of relatively low firing rate. Amount of $NO_x$ emission is maximum at near stoichiometric excess air ratio, which is chemiluminescence intensity is maximum.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.12 s.243
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• pp.1299-1306
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• 2005

The suitable pressure regulator modeling at each opening ratio and pressure ratio is very important to obtain reliable results, especially in small scale pipeline network analysis such as a pressure regulator system. And it is needed to confirm both whether temperature recovery is achieved after passing by the pressure regulator's narrow neck and how much amount of low temperature area that can cause condensate accumulation is distributed by various PCV models and driving conditions. In this research, the numerical model resembling P company pressure regulator that is used widely for high pressure range in commercial, is adopted as the base model of CFD analysis to investigate pressure regulator's flow characteristics at each pressure ratio and opening ratio. And it is also introduced to examine pressure regulator's critical flow characteristics and possibility of condensation or freezing at each pressure ratio and opening ratio. Additionally, the comparison between the results of CFD analysis and the results of analytic solution obtained by compressible fluid-dynamics theory is attempted to validate the results of CFD modeling in this study and to estimate the accuracy of theoretical approach at each pressure ratio and opening ratio too.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.1
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• pp.71-82
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• 2016

PURPOSE: The purpose of this case report was to determine the effect of therapeutic exercise on posture, pain, and muscle activity in two patients with forward head posture (FHP). METHODS: A-31-year-old male (patient A) and a 19-year-old women (patient B) presented with FHP, neck pain, and headache. The therapeutic exercise program consisted of cervical mobilization, deep cervical flexors strengthening, and cervical extensors stretching, for 40 min/d, 2 d/week, for 8 weeks. Neck pain (VAS), neck disability (NDI), cervical range of motion (CROM), lateral view of cervical spine X-ray (indicating the FHP), and asymmetrical neck and shoulder muscular activity ratio were measured before, after 4 weeks, and after 8 weeks of corrective exercise. RESULTS: VAS and NDI decreased in patients A and B after exercise compared to before the program. CROM increased in patients A and B at flexion, extension, side bending, and rotation after exercise compared to before the program. FHP decreased in patients A and B at distance after exercise compared to before the program. In addition, asymmetrical neck and shoulder muscles activity ratio improved in patients A and B after exercise compared to before the program. CONCLUSION: We demonstrated in a case report that therapeutic exercise increases ROM, decreases pain and disability of neck, FHP, and asymmetry muscle activity ratio in patients with FHP. These finding have clinical implications for therapeutic exercise in patients with FHP.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.614-621
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• 2002

This study was performed to investigate the behavior of vapor phase of fuel mixtures with different piston bowl shapes(F, B and R-type) in a optically accessible engine. The images of liquid and vapor phases were captured in the motoring engine using exciplex fluorescence method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. Injection pressure was 5.1MPa. Two dimensional spray fluorescence image of vapor phase was acquired to analyze spray behaviors and fuel distribution inside of cylinder. Four injection timings were set at BTDC 90$^{\circ}$, 80$^{\circ}$, 70$^{\circ}$, and 60$^{\circ}$. With a fuel injection timing of BTDC 90$^{\circ}$, fuel-rich mixture level in the center region was highest in a B-type piston. With a fuel injection timing of BTDC 60$^{\circ}$, R-type piston was best. R-type piston shape was suitable under enhanced swirl ratio and late injection condition and B-type piston shape was right in a weak swirl ratio. It was found that the piston bowl shape affected the mixture stratification inside of cylinder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.563-567
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• 2002

Developing base data on luring fish schools into netting position by the use of underwater audible sound on japanese parrot fish Oplegnathus fasciatus found in the coastal waters of Jeju Island, S. Korea. Auditory threshold was determined by the heartbeat condition technique using pure tones coupled with a delayed electric shock. The audible range of japanese parrot fish extended from 80 Hz to 500 Hz with a peak sensitivity at 200 Hz. The mean auditory thresholds at the frequencies of 80 Hz, 100 Hz, 200 Hz,300 Hz and 500 Hz were 104 dB, 95 dB, 91 dB, 99 dB and 113 dB, respectively. As the frequency became higher than 200 Hz, the auditory threshold increased almost linearly with increasing frequency. Critical ratios of fishes measured in the presence of masking noise in the spectrum level range of 69$\~$78 dB (0 dB re 1$\mu$Pa/$\sqrt{Hz}$) ranged from 21 dB to 40 dB at test frequencies. The noise spectrum level at the start of masking was about 70 dB within the test frequency range. The sound pressure level of 100$\~$200 Hz recognized by japanese parrot fish under the ambient noise is above 91 dB and the critical ratio for them is above 21 dB.

• Korean Journal of Human Ecology
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• v.17 no.1
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• pp.151-158
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• 2008

This study examines the cooking quality, rheology, and sensory characteristics of ramyon noodles made from Korean wheat and arrowroot starch. The control was made from Australian standard wheat(ASW) and the sample was made from Korean wheat. The ratios of arrowwood starch in the sample group were 0%, 5%, 10%, 15%, 20%, 25%, and 30% respectively, and the result was as follows: the yield of the arrowwood starch was 18.8% and moisture level was 14.2%. The lightness(L), redness(a), and yellowness(b) of ASW were 92.07, 1.44, 10.22 respectively, whereas those of Korean wheat were 92.05, 1.55, 11.01, which means the two kinds of wheat showed very little difference in lightness, but Korean wheat had higher degrees of a and b than ASW. The color value of arrowroot starch is L 72.65, a 3.44, b 12.92, so it has a lower degree of lightness and higher degrees of a and b than two kinds of wheat. Dried ramyon displayed a lower degree of lightness and higher degrees of a and b than cooked ramyon, but the first decreased and a increased as we increased the ratio of arrowroot starch in it. The weight of dried ramyon did not show a significant difference among the groups. On the other hand, the weight, volume, water absorption, and the turbidity of cooked ramyon increased as we increased the amount of arrowroot starch in it. The maximum weight, solidity, and elasticity of the control group were greater than those of ramyon made from Korean wheat, but its brittleness was lower. The two groups showed the same degrees of hardness, adhesiveness, and cohesiveness. The maximum weight, solidity, and adhesiveness of the control group increased as we increased the amount of arrowroot starch in it, and the hardness and brittleness were great when the ratio of arrowroot starch was 20%; elasticity was greatest when the ratio of arrowroot starch was 15, 20, and 25%; its adhesiveness and cohesiveness did not depend on the amount of arrowroot starch in it. In the sensory characteristics evaluation, the items that showed significant differences include: appearance (p<0.01), color(p<0.01), smell(p<0.001), transparency(p<0.05), and overall acceptability(p<0.05). The ramyon earned the highest score in appearance when the ratios of arrowroot starch were 5%, 15%, and 20%. As for color and smell, it earned the highest score when it contained 20 and 25% of arrowroot starch. The transparency decreased as we increased the amount of arrowroot starch, and overall acceptability was highest when the ratio of arrowroot starch was 15%. There was a significant difference in overall acceptability between the control and the sample group. As for the loosing speed and chewiness, there was no significant difference between the two groups. When we look at the result of various tests to evaluate the cooking quality, rheology, and sensory characteristics of ramyon noodles, ramyons that contained 15 to 25% of arrowroot starch earned the high scores, and of these the one with 20% of arrowroot starch earned the highest score on all accounts.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.342-346
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• 2006

A polymeric ring resonator with electrically variable extinction ratio at resonant wavelengths has been proposed and demonstrated. It consists of a ring waveguide coupled to a straight bus waveguide and a modulating electrode, which is formed in the outer cladding region outside of the ring. When electrical power is applied to the electrode, the refractive index of the polymers underneath the electrode is lowered to strengthen the confinement of the guided mode of the ring and thus the equivalent effective refractive index felt by the mode is decreased. Therefore, the propagation loss of the guided mode is reduced with the applied electrical power Consequently the extinction ratio at resonant wavelengths is varied by the electrical power. For the achieved results, the extinction ratio was changed by about 9 dB for the electrical power of 12 mW, when the propagation loss of the ring was reduced by 80 dB/cm.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.129-135
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• 1996

This paper presents the effectiveness of the dynamic vibration absorber consisting of a single mass, coil springs and oil damper on the resonance freauency ratio and amplitude ratio for damped linear systems, that is, primary vibration system with damping. The effects of the dynamic vibration absorber are investigated numerically and experimentally for values of mass ratio, natural frequency ratio, and damping ratio. The experimental results show good agreement with calculated ones. As a result, the characteristics shown by the present work are useful in optimal tuning the dynamic vibration absorber in practice.

• Progress in Superconductivity
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• v.13 no.2
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• pp.105-110
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• 2011

SQUID sensor-based ultra low-field magnetic resonance apparatus with ${\mu}T$-level measurement field requires a strong prepolarization magnetic field ($B_p$) to magnetize its sample and obtain magnetic resonance signal with a high signal-to-noise ratio. This $B_p$ needs to be ramped down very quickly so that it does not interfere with signal acquisition which must take place before the sample magnetization relaxes off. A MOSFET switch-based $B_p$ coil driver has current ramp-down time ($t_{rd}$) that increases with $B_p$ current, which makes it unsuitable for driving high-field $B_p$ coil made of superconducting material. An energy cycling-type current driver has been developed for such a coil. This driver contains a storage capacitor inside a switch in IGBT-diode bridge configuration, which can manipulate how the capacitor is connected between the $B_p$ coil and its current source. The implemented circuit with 1.2 kV-tolerant devices was capable of driving 32 A current into a thick copper-wire solenoid $B_p$ coil with a 182 mm inner diameter, 0.23 H inductance, and 5.4 mT/A magnetic field-to-current ratio. The measured trd was 7.6 ms with a 160 ${\mu}F$ storage capacitor. trd was dependent only on the inductance of the coil and the capacitance of the driver capacitor. This driver is scalable to significantly higher current of superconducting $B_p$ coils without the $t_{rd}$ becoming unacceptably long with higher $B_p$ current.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.469-474
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• 2009

Purpose: A lower facial contouring surgery has become a commonly performed procedure in Asia. Currently, mandibular angle sagittal ostectomy and botulinum toxin type A treatment are main procedures for aesthetic correction of a broad lower face. There are a few date to show the differences in the mandibular contouring changes between mandibular angle splitting ostectomy and botulinum toxin type A treatment. Facial golden mask is easy to apply, inexpensive, and relatively objective for evaluation of facial contour analysis. This study was designed specifically to compare the changes in lower face width after two different forms of lower facial contouring procedure using facial golden mask. Methods: Seventeen patients, aged 18 to 55 years (mean, 28.6 years), 15 women and 2 men, consented to the study and receive a contouring procedure of lower face. The patients were classified in to 2 groups. In group A, the sample consisted of 10 patients with a prominent squared mandibular angle and mandibular angle splitting ostectomy was performed. In group B, the sample consisted of 7 patients with masseteric hypertrophy and botulinum toxin type A treatment was performed. Photographs of the face were taken to record the facial change at preoperative and postoperative. The postoperative photographs were taken to considered maximal effect at 2 years after surgery in group A and 4.8 months after treatment in group B. The authors applied the facial golden mask to preoperative and postoperative photographs and horizontal ratio, which compares facial width with golden mask width, were calculated. We made an analysis of the result of horizontal ratio using SPSS. Results: Overall average horizontal ratio of pre- and postoperative photos of group A were 1.24 and 1.11, whereas overall average horizontal ratio of pre- and postoperative photos of group B were 1.19 and 1.12. The horizontal ratio decreased 10.24% in group A and 5.93% in group B. There was a statistically significant change in before and after treatment, but there was no significant change in comparing the group A and group B. Conclusions: The result from this study suggest that mandibular angle sagittal ostectomy and botulinum toxin type A treatment showed relatively satisfactory clinical effects on lower facial contouring treatment. There was no statistical significant difference within two lower facial contouring treatment. Facial golden mask is easy to apply, inexpensive, and relatively objective, so we think that facial golden mask is a good method for evaluation of lower facial contouring treatment.