• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.6
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• pp.22-29
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• 2002

The conventional neon transformer systems are very bulky and heavy because it consist of leakage type transformers made of silicon steel plates. In addition, it has problems in noise by a neon transformer and in possibilities of fire and electrical shock when neon tubes are destroyed. A protection circuit is designed for all types of neon transformer loaded with one or more neon tubes. Whenever the neon tube fails to be started up, comes to the life end, encounters faults with open-circuits at the output terminals of the neon transformer, the protection circuit will be initiated to avoid more critical hazards. The input of the transformer is automatically cut off when the abnormal condition occurs, preventing waste of no-load power. To improve such problems, in this paper, a new type of neon power supply systems for neon tube is designed and implemented using inverter type circuits and a newly designed lightweight transformer. In the developed neon transformer system, a 60［Hz］power input is converted to 20［KHz］high frequency using half-wave inverters, thereby the transformer reduces its size by 1/5 in volume and 1/10 in weight.

• Journal of Veterinary Clinics
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• v.34 no.2
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• pp.108-111
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• 2017

A 4-year-old, weighing 7.6 kg, castrated male, Pug presented with ingestion of gastric cavity foreign body. Physical examination revealed panting, retching and hyper-salivation. Blood chemistry and complete blood cell count were normal, but hypophosphatemia was observed. An abdominal radiograph revealed the foreign body (FB), round shape and 2 cm length, at the pyloric region of stomach. A thoracic radiograph revealed an incidental metal FB, 3.5 cm length, at the cranial portion of the diaphragm. An upper gastrointestinal endoscopy was performed to remove the FB in the stomach and then a peach-pit was removed. However the metal FB was not found in the esophagus therefore a lateral thoracotomy was performed. A right lateral thoracotomy through the $7^{th}$ intercostal space was accomplished to expose the right caudal lung lobe. After open the thoracic cavity, foreign body was not observed by gross evaluation and caudal lung lobe was attached to the diaphragm. The FB was identified inside the lung lobe and surrounded by granulation tissue. The metal FB (sewing needle) was removed with blunt dissection and incised lung lobe was sutured using absorbable suture material PDS 4-0 with interrupted suture. A thoracotomy tube was inserted into the thoracic cavity during surgery. Patient's respiration became stable after surgery. A chest tube was removed 3 days after surgery. No complications were noted and the dog was discharged 4 days after surgery. In small animal, foreign body ingestion is a common reason for emergency. After ingestion of the FB, perforation through the esophagus and migration to inside the lung lobe is not common in small animals. In this case, thoracic metal FB was identified incidentally and removal of a thoracic FB with thoracotomy was performed successfully.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.253-261
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• 1987

Thermoacoustic oscillation of an air column induced by heated wires is investigated analytically and experimentally. Acoustic power generation from a single heater wire is estimated based on the result of heat transfer analysis and expressed in terms of the efficiency factor indicating the conversion efficiency from heat to acoustic energy. It is shown that the efficiency factor becomes maximum when the wire radius is the order of the coustic boundary layer thickness and the flow velocity is close to the thermal diffusion velocity. Onset condition of the column oscillation is obtained by equating the acoustic power generation at the heater to the power loss due to thermoviscous dissipation at the tube wall and the convection and radiationloss at the open ends of the tube. In estimating the acoustic power generation, the heater is treated as a stretched single wire by correcting the flow velocity to take into account the interactions between adjacent heater wires. Experiment is performed by using a spiral heater of 1mm diameter in an air column of 37mm diameter. The heat input to drive the oscillation is measured and compared with the theoretical prediction. A good agreement is found between the theory and experiment, which is regarded as a substantial verification of the present analysis.

• Journal of Chest Surgery
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• v.32 no.2
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• pp.164-170
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• 1999

Background: The diffuse infiltrative lung disease often requires biopsy for its final diagnosis. Unlike the limited exposure that can be achieved through small thoracotomy incisions in open lung biopsy technique, the thoracoscopic approach allows visualization and biopsy of nearly entire surface of the lung without morbidity of large standard thoracotomy. The purpose of this study was to compare the diagnostic efficacy and operative safety of thoracoscopic lung biopsy(TLB) with open lung biopsy(OLB) in the diagnosis of diffuse infiltrative lung disease. Material and Method: From March 1993 to August 1997, 81 patients were referred for diagnostic lung biopsy. 51 of them underwent standard open lung biopsy and the remaining 30 patients underwent thoracoscopic lung biopsy. Result: Mean operative time was 63 minutes for TLB and 79 minutes for OLB (p=0.04). The volume of biopsy specimen was not different between two groups(TLB 7.8 cm3, OLB 6.9 cm3 : p=0.72) and the diagnostic accuracy of each methods was comparable (TLB 100%, OLB 96%). The duration of hospital stay was significantly less in TLB (TLB 13days, OLB 22days : p=0.01). The duration of parenteral narcotics administration was also less for TLB(TLB 2.5days, OLB 5.2days, p=0.05). Meanwhile, the duration of chest tube drainage, the frequency of parenteral narcotic injection were not significantly different between two groups. Complications occurred in 2 among the TLB patients (6.67%) and 4 among the OLB patients (7.84%). There was no operative mortality in both groups. Conclusion: We concluded that TLB is a good alternative procedure to OLB in the diagnosis of diffuse infiltrative lung disease with lower morbidity and comparable diagnostic accuracy.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.5 no.1
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• pp.5-10
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• 1994

In vivo canine model was made in two mongrel dogs under the general Ⅰ-Ⅴ anesthesia. A vertical skin incision was made on the neck, the larynx and the trachea were dissected. Two tracheal openings were made : lower one for the insertion of the anesthesia tube and upper one for the delivery of air to the larynx to induce phonation. External branch of the superior laryngeal nerves and recurrent laryngeal nerves bilaterally were identified and stimulated electrically constantly. Subglottic pressure. fundamental frequency, intensity, and open quotient were measured when the air flow rate was varying low, medium and high. Glottic resistence was calculated. As the air flow rate was increased, the subglottic pressure and the sound intensity were increased. However, glottic resistance was decreased as the air flow was increased. In falsetto register, fundamenatal frequency was increased with the increment of air flow, but in modal register fundamental frequency was not increased statistically significant Open quotient by the electroglottography was increased according to the increment of airflow.

• Advances in pediatric surgery
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• v.13 no.1
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• pp.13-22
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• 2007

Fundoplication is accepted as an effective treatment of gastroesophageal reflux disease. The recent results of laparoscopic fundoplication demonstrated safety and less morbidity, shorter hospital stay and less pulmonary complication compared to the open operation. Laparoscopic fundoplication has been our first choice of operation for gastroesophageal reflux disease since 2003. Among 29 cases, there were 2 conversion cases because of severe distension of transverse colon and hepatomegaly. We studied 27 consecutive patients operated upon from January 2003 through December 2004. There were 15 boys and 12 girls, ages from 1.5 months to 12 years (median 25.3 months). Body weight ranged from 2.9 kg to 37 kg (median 9.8 kg). Neurological abnormalities were present in 23 patients. Indications for surgery included medically refractory reflux associated with vomiting, pneumopathy, otorhinolaryngologic pathology, failure to thrive, esophagitis, apnea and bradycardia. We used 4-5 trocars of 5 mm or 12 mm with $30^{\circ}$ telescope and performed the Nissen technique in all patients. In neurological impaired patients, gastrostomy tube was placed at the time of fundoplication. Median operative time was 130 minutes (70 - 300 minutes). There was no mortality nor intraoperative complication. Twenty-six patients were followed for median of 19 months (8 - 31 months). Four patients (15.4 %), who were all neurological impaired, developed recurrent symptoms of gastroesophageal reflux disease. Two of these patients had reoperation (1 laparoscopic approach, 1 open method). There were significant increases in body weight in 11 patients after fundoplication. Laparoscopic fundoplication is acceptable as a safe and effective method for gastroesophageal reflux disease.

• Korea-Australia Rheology Journal
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• v.13 no.1
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• pp.29-35
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• 2001

The development of filament stretching extensional rheometers over the past decade has enabled the systematic measurement of the transient extensional stress growth in dilute and semi-dilute polymer solutions. The strain-hardening in the extensional viscosity of dilute solutions overwhelms the perturbative effects of capillarity, inertia & gravity and the kinematics of the extensional deformation become increasingly homogeneous at large strains. This permits the development of a robust open-loop control algorithm for rapidly realizing a deformation with constant stretch history that is desired for extensional rheometry. For entangled fluids such as concentrated solutions and melts the situation is less well defined since the material functions are governed by the molecular weight between entanglements, and the fluids therefore show much less pronounced strain-hardening in transient elongation. We use experiments with semi-dilute/entangled and concentrated/entangled monodisperse polystyrene solutions coupled with time-dependent numerical computations using nonlinear viscoelastic constitutive equations such as the Giesekus model in order to show that an open-loop control strategy is still viable for such fluids. Multiple iterations using a successive substitution may be necessary, however, in order to obtain the true transient extensional viscosity material function. At large strains and high extension rates the extension of fluid filaments in both dilute and concentrated polymer solutions is limited by the onset of purely elastic instabilities which result in necking or peeling of the elongating column. The mode of instability is demonstrated to be a sensitive function of the magnitude of the strain-hardening in the fluid sample. In entangled solutions of linear polymers the observed transition from necking instability to peeling instability observed at high strain rates (of order of the reciprocal of the Rouse time for the fluid) is directly connected to the cross-over from a reptative mechanism of tube orientation to one of chain extension.

• Journal of the Korea Society of Computer and Information
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• v.25 no.8
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• pp.55-63
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• 2020

Recently, people have come to enjoy using movies and music applications, such as YouTube, Netflix, and Watcha Play, on their smart devices while riding public transportation. However, they sometimes miss their destination stations because of these activities. Therefore, in this paper, we propose a disembarking notification system for public city buses using smart devices and high frequencies generated via the buses' speakers. The high frequencies are generated by the public buses' station information broadcasters. Smart devices then analyze the high-frequency signals with their inner microphones, and the proposed application displays a disembarking notification to the user when the user's destination or stop-over station's signal is the same. To evaluate this system's performance, we tested 1,000 real-time disembarking notifications, and the test results showed 98.9% accuracy. Moreover, we compared these results to those using only OpenAPI, and our proposed system featured far better outcomes. Thus, this proposed notification system can prove a useful technology for many people who often use public city buses, as it can notify specific users of their destination stations. Furthermore, this system will become innovative technology for global public transportation by informing users of their desired stations using speakers.

• Journal of Chest Surgery
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• v.31 no.4
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• pp.369-373
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• 1998

The bullectomy through the limited transaxillary thoracotomy and video-assisted thoracic surgery(VATS) had been used in operative management of spontaneous pneumothorax from Jan. 1994 to July 1997. The study comprised a retrospective review of 42 cases which were treated by limited thoracotomy, and 61 cases treated by video-assisted thoracoscopic sugery. We retrospectively reviewed annual incidnce of bullectomy. Analysis of video-assised thoracoscopic surgery and open bullectomy including age, sex, operative sites, surgical indications, associated diseases, operative time, posoperatve complications and hospital courses. There was no significant difference for operation time in two groups, 98.3${\pm}$38.4 minutes in thoracotomy and 95.7${\pm}$31.5 minutes in VATS. Prolonged air leakage over 7 days was observed in 8 cases from thoracotomy group, 4 cases from VATS group. 3 cases of recurrent pneumothorax were found from VATS group, but no recurrence was occurred from open bullectomy group. There were significant differences in postoperative hospital stay (8.0${\pm}$3.9 day in thoracotomy vs 5.9${\pm}$2.4day in VATS(P=0.001)), and indwelling period of chest tube after operation( 5.8${\pm}$3.0day in thoracotomy vs 4.0${\pm}$2.0day in VATS(P=0.0006)).

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.7
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• pp.915-921
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• 2020

Thermoacoustic instability caused by air conditioning in a combustion chamber has emerged as a problem that must be solved to establish a stable combustion system. Thermoacoustic instability is largely divided into primary and secondary acoustic instability. In this study, an experimental study of the effects of heat losses was conducted to investigate the mechanism of secondary acoustic instability. To generate the secondary acoustic instability, a quarter-wavelength resonator with one open end and one closed end was used, and the inside of the resonator was filled with premixed gases. Subsequently, secondary acoustic instability with downward-propagating flames could be realized via thermal expansion on the burnt side. To control heat losses qualitatively, an additional co-axial tube was installed in the resonator with air or nitrogen supply. Therefore, additional diffusion flames can be formed at the top of the resonator depending on the injection of the oxidizer into the co-axial tube when rich premixed flames are used. Consequently, secondary acoustic instability could not be achieved by increasing heat losses to the ambient when the additional diffusion flame was not formed, and the opposite result was obtained with the additional diffusion flame.