• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.592-600
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• 2005

In this paper, a low loss magnetic levitation(Maglev) system is suggested and tested. The suggested Maglev system includes four hybrid magnets which consist of permanent magnet and coil. In the steady state, the levitated module system can be supported by attraction force generated by permanent magnet. The coil current controls only dynamic loads due to external disturbances. The module systems are designed by using finite element method(FEM) software tools such as MAXWELL and ANSYS. Also, digital control systems are designed to keep the magnet airgap at a constant value. The control systems include a VME(versa module europa)-based CPU(central processing unit) board, AD(analog to digital) board, PWM(pulse width modulation) board, 4-quadrant chopper, and sensors. In order to estimate the vertical velocity of the magnet, we use second order state observer with acceleration and gap signals as input and output signals, respectively. The characteristics of the suggested low loss Maglev system are demonstrated by experimental results showing coil current of 0A in the steady state of 3m airgap and performance specifications are satisfied for reference gap and force disturbance.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.511-518
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• 1998

In order to develop the aerosol bolus technique which is thought to be a potential tool for probing geometries or abnormalities of small airways, an experimental system of measuring fast time variations of particle concentration in the inhaled and exhaled breathing air was developed. The system generates monodisperse sebacic acrid particles of 1 micron size and 1.2 of geometric standard deviation in high concentration of $10^8$ particles/cc, delivers a short pulse of particles at the controlled instant during inhalation using a solenoid valve, and measures the fast change of particle concentration in using the laser light scattering. Successful operation of the generator and the measuring system was confirmed by smooth concentration profiles in inhalation. It was also confirmed that maintaining a constant breathing rate is essential to stable outputs and any disturbance in flow rate near the mode (maximum concentration) induces a large number of spurious peaks in the exhalation. Experimental data without strict control of breathing flow rate showed a substantial amount of scatter. The measured results showed an improvement in scatter over the existing results. When compared with theoretical predictions from 1-D convective diffusion equation and other experiments, general characteristics of dispersion for several penetration depths showed a good agreement, but there exists some difference in absolute values, which is attributed to the difference in body conditions. Improvements are needed in the theory, especially in relation to correcting for the effect of breathing flow rate.

• Journal of The Korean Society of Clinical Toxicology
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• v.4 no.1
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• pp.44-47
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• 2006

Symptoms of aspirin overdose may vary from acid-base disturbance, electrolyte abnormality, non-cardiogenic pulmonary edema, chemical hepatitis, seizure to cardiac toxicity. Cardiac adverse effects from aspirin are uncommon but there are reports of arrhythmia, cardiopulmonary arrest, and myocardial infarction. We report 2 cases of young women with aspirin overdose who exhibited ischemic changes on their ECGs a few hours after the ingestion with spontaneous recovery in a few days. First case, a 29 year old woman, presented to the emergency department 6 hours after ingesting 250 tablets of aspirin (325 mg/T). On examination, the temperature was $36.3^{\circ}C$: blood pressure, 105/72mmHg; Pulse, 111/min and respiratory rate, 24/min. Second case, a 27 year old woman, an hour after ingesting 60 tablets (325mg/T). On examination, the temperature was $36.0^{\circ}C$: blood pressure, 102/72 mmHg; pulse, 89/min and respiratory rate, 25/min. In both cases, ECG after 6 hours of ingestion had sinus tachycardia and developed T wave inversion on the anterior leads in the following ECGs. Their initial serum salicylate levels after 6 hours of ingestion were 71.2 mg/dL and 28.4 mg/dL respectively. These salicylate levels were resolving when these ECGs were observed. The ECG changes resolved in the following days and they were discharged without any further symptoms. Further studies are needed, but for the time being, when dealing with salicylate overdose, transient cardiac depression should be kept in mind to avoid adverse ischemic cardiac events.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.65-72
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• 2001

This paper deals with a novel full digital control of the single-phase PWM(Pulse Width Modulation) inviter for UPS(Uninterruptible Power Supp1y). The voltage and current of output filter capacitor as a state variable are the feedback control input. In the proposed scheme a double deadbeat control consisting of minor current control loop and major voltage control loop have been developed In addition, a second order deadbeat currents control which should be exactly equal to its reference in two sampling time without error and overshoot is proposed to remove the influence of the calculation time delay. The load current prediction is achieved to compensate the load disturbance. The simulation and experimental result shows that the proposed system offers an output voltage with THD(Total Harmonic Distortion) less than 5% at a full nonlinear load.

• Fisheries and Aquatic Sciences
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• v.11 no.2
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• pp.103-112
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• 2008

Compressional sound velocities of shelf sediments in the South Sea of Korea, were measured in situ and in the laboratory for six cores. In situ sound velocity was measured using the Acoustic Lance (frequency of 7.5-15 kHz), while laboratory velocity was measured by the pulse transmission technique (frequency of 1MHz). Physical properties were relatively uniform with sediment depth, suggesting little effect of sediment compaction and/or consolidation. Average in situ velocity at each core site ranged from 1,457 to 1,488 m/s, which was less than the laboratory velocity of 1,503 and 1,604m/s. In muddy sediments the laboratory velocity was 39-47 m/s higher than in situ velocity. In sandy sediments, the difference was greater by an average of 116 m/s. Although the velocity data were corrected by the velocity ratio method based on bottom water temperature, the laboratory velocity was still higher than the in situ velocity (11-21 m/s in muddy sediments and 91 m/s in sandy sediments). This discrepancy may be caused by sediment disturbance during core collection and/or by the pressure of Acoustic Lance insertion, but it was most likely due to the frequency difference between in situ and laboratory measurement systems. Thus, when correcting laboratory velocity to in situ velocity, it is important to consider both temperature and frequency.

• Journal of Genetic Medicine
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• v.15 no.1
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• pp.20-23
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• 2018

Point mutations in the human cardiac homeobox gene NKX2.5 are associated with familial atrial septal defect (ASD), atrioventricular (AV) conduction disturbance, as well as sudden cardiac death. To date, more than 60 NKX2.5 mutations have been documented, but there are no reports in Korea. We are reporting the first Korean family with ASD and AV block associated with a novel mutation in the NKX2.5 coding region. A 9-year-old boy presented with a slow and irregular pulse, and was diagnosed with secundum ASD and first degree AV block. The boy's father, who had a history of ASD correction surgery, presented with second degree AV block and atrial fibrillation. The boy's brother was also found to have secundum ASD and first degree AV block. There were two sudden deaths in the family. Genetic testing revealed a novel mutation of NKX2.5 in all affected members of the family.

• Tuberculosis and Respiratory Diseases
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• v.50 no.4
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• pp.415-425
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• 2001

Background : The correlation between the high resolution computed tomography(HRCT) emphysema score and the physiologic parameters including resting and exercise pulmonary function test was investigated in 14 patients($60.6{\pm}10.3$ years) with pulmonary emphysema. Methods : The patients underwent a HRCT, a resting pulmonary function test, and incremental exercise testing(cycle ergometer, 10 W/min). Computed tomography scans were obtained on a GE highlight at 10 mm intervals using 10 mm collimation, from the apex to the base after a full inspiration. The emphysema scores were determined by a CT program 'Density mask' outlining the areas with attenuation values less than -900 HU, indicating the emphysema areas, and providing an overall percentage of lung involvement by emphysema. Results : Among the resting PFT parameters, only the diffusing capacity(r=-0.75) and $PaO_2$ (r=-0.66) correlated with the emphysema score(p<0.05). Among the exercise test parameters, the emphysema score correlated significantly with the maximum power(r=-0.74), maximum oxygen consumption(r=-0.68), anaerobic threshold(V-slope method: r=-0.69), maximal $O_2$-pulse(r=-0.73), and the physiologic dead space ratio at the maximum workload(r=-0.80)(p<0.01). Conclusion: We could find that exercise testing parameters showed a much better correlation with the HRCT emphysema score, which is known to have a good correlation with the pathologic severity than the resting PIT parameters. Therefore it is suggested that exercise testing is superior to resting PIT for estimating in the estimation of the physiologic disturbance in emphysema patients.

• Journal of Chest Surgery
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• v.10 no.1
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• pp.98-105
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• 1977

A 36 year old blindman, engineer was admitted with chief complaints of hemoptysis, recurrent sore throat, pyoderma in genital organ, uveitis and thrombophlebitis for 10 years. Above the chief complaints were remission or exacerbation during hospitalization. Physicalexamination showed that left radial, ulnar & brachial pulse was not palpable. No bruit or murmur was obtained over the mass. Neurologic examination revealed no significant finding.On admission, chest P-A showed hen egg sized round & oval compact hazy density on left upper lung field. Bronchogram revealed no pathological finding and Lt. tomogram showed well define large,ovoid mass density in the superior mediastinum. Fluoroscopy finding showed nonpulsatile on left upper lung field. Pre-op. aortography was not taken, under the impression of lung Ca. rule out .sortie aneurysm, exploratory operation was performed through the 2nd intercostal space, Lt. It was performed that the mass was ascending sortie aneurysm of saccular type. Direct aneurysmectomy with multiple figure of eight suture were done without any prosthetic graft. Post-op. control I.V.C graphy showed completely obstruction sign. Postopcontrol aortography revealed good surgical result. Final, histopathological answered non-specific sortie aneurysm, saccular type. Post-op. courses were uneventful except mild neurologic disturbance with subclavian steal syndrome and associated with both lower leg pitting edema due to inferior vena cava obstruction. After op, 3 month later, discharged to home, with big systemic problem. Behcet`s syndrome reviewed with related literatures. The coexistence of mouth and genital ulceration with hypopyon mentioned by hippocrates and described by various workers in the early part of this century was first defined as a syndrome by Behcet in 1937. In 1937 Behcet described a chronic relapsing triple symptom complex of oral ulceration, genital ulceration, and ocular inflammation. The place of the syndrome as part of a systemic disorder in now clearer, and the under lying pathology appears to be a vasculitis. The disease runs a- chronic course, blindness being the greatest disability and control nervous system involvement a cause of death. Thrombophlebitis is fairly frequent, france et al [1951] giving an incidence of 25% and Dowling [1961] 12%, superficial thrombophlebitis migrans and thrombosis of large veins, including venae cavae [Thomas, 1947: Boolukos 1960] are recorded. Little attention has been paid to arterial involvement. Mishima et al. [1961] described resection cf an aortic aneurysm in a 38 year old man with Behcet`s syndorme. Mounsey in a clinicopathological conference described a case [Brit, med. J., 1966] of ruptured aortic aneurysm in Bechcet`s syndrome treated by aorto-iliac graft. Also, Shikano and Oshima et al [1963] recorded two aneyrysm of smaller arteries. Unfrequently, aortic aneurysm was presumed to be secondary to osteomyelitis of the lumber spine, though the possible association between aortic aneurysm and Behcet`s syndrome was raised. A further case is reported here, in which ascending aortic aneurysm with Behcet`s Ds. appeared to form part of this generalized disease. This is a case report of surgical experience of Behcet`s Ds. with ascending aortic aneurysm which had nearly all the typical clinical features. Above mentioned and was reviewed with related literatures.

• The Korean Journal of Nuclear Medicine
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• v.12 no.2
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• pp.23-31
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• 1978

Hyperthyroidism may be defined as those clinical conditions which result from an increase in the circulating levels of one or both thyroid hormones. Hyperthyroidism in broad sense could be classified with toxic diffuse goiter, toxic adenomatous goiter, and toxic multinodular goiter on the basis of the circulating thyroid hormone levels. For this study, the subject included 94 cases with hyperthyroidism were presented in 77 with toxic diffuse goiter, 8 with toxic adenomatous goiter, and 9 with toxic multinodular goiter on the levels of $^{125}IT_3$ resin uptake rate and serum thyroxine ($T_4$). The observed results were as follows: 1) In the cases of hyperthyroidism including toxic diffuse goiter, toxic adenomatous goiter, and toxic multinodular goiter, 20.21% of the patients were male and 79.79% female. The majority of the patients were in 2nd to 4th decades of their lives. 2) There were objective signs clearly manifested in hyperthyroidism including toxic diffuse goiter and toxic adenomatous goiter which were rare in the multinodular goiter. The clinical signs in toxic diffuse and toxic adenomatous goiter included wide pulse pressure, tachycardia, systolic murmur, exophthalmos, tremor and warm skin etc. (Table 3.) 3) The most freauent complaints of the patients with hyperthyroidism were palpitation, weight loss, increased appetite, perspiration, heat intolerance, nervousness, exertional dyspnea, and menstrual disturbance etc. (Table 4.) There was no clear difference in the incidence of symptoms between toxic diffuse goiter and toxic adenomatous goiter, but there was clear difference between toxic multinodular goiter. 4) Considering of results of $^{125}IT_3$ resin uptake rate and serum $T_4$ level in toxic diffuse goiter, toxic adenomatous goiter and toxic multinodular goiter, $^{125}I\;T_3$ resin uptake rate was $49.15{\pm}9.94%$ (mean) and serum $T_4\;21.29{\pm}7.04ug/dl$ (mean) in toxic diffuse goiter. In toxic multinodular goiter, $^{125}I\;T_3$ resin uptake rate was $32.47{\pm}6.74%$ (mean) and serum $T_4$ level $11.03{\pm}5.0ug/dl$, and then there was clear difference in the results of $^{125}I\;T_3$ resin uptake rate and serum $T_4$ between toxic diffuse goiter and toxic multinodular goiter. The levels of $^{125}I\;T_3$ resin uptake rate and serum $T_4$ in toxic adenomatous goiter were $40.32{\pm}13.08%$ (mean), $15.47{\pm}8.25ug/dl$ (mean) respectively, so there was no clear difference between toxic diffuse goiter and toxic adenomatous goiter. 5) There was no significant differnece in length and width performed with thyroid scanning in toxic diffuse goiter, toxic adenomatous goiter, and toxic multinodular goiter.

• Journal of Wetlands Research
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• v.19 no.3
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• pp.327-334
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• 2017

The flood pulse in streams enhances the biodiversity and ecosystem services of the channel-floodplain ecosystems by exchanging water, nutrients, sediments and organisms. However, the lateral connectivity in most streams of Korea has been disrupted by the levee constructions for the purpose of flood control and land use of floodplains. To compare the characteristics of floodplain vegetation according to existence of lateral connectivity in streams, we investigated the geomorphological and soil environmental factors and structures and distribution of vegetation in the floodplains connected and isolated by levee to the channel in Cheongmi Stream, Seom River, Hwangguji Stream, Mangyeong River, Gomakwon Stream, and Boseong River, Korea. In comparison of soil environments, moisture and clay contents were higher in the isolated floodplain than in the connected floodplain. According to the result of principal component analysis (PCA) using environmental data, the environments of the connected floodplain and the isolated floodplain were separated by soil moisture contents, soil texture and distribution altitude of the vegetation. The results of detrended correspondence analysis (DCA) using vegetation data showed that the isolated floodplain was dominated by the hydropythic communities of diverse life form and that the connected floodplain was dominated by the hygrophytic communities that endure disturbance. In conclusion, it is thought that the vegetation of the floodplain changed to the lentic wetland vegetation dominated by diverse hydrophytes as the floodplain was isolated from the channel by artificial levees.