• Proceedings of the KIEE Conference
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• summer
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• pp.1184-1186
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• 2004

Focus Electrode(FE) 기능을 갖는 진행파관 증폭기(TWTA)를 구동하기 위하여 고전압 펄스전원 장치가 필요하다. 이 전원장치는 영부터 -5.0 kV TWT 캐소드 고전압 위에서 펄스 출력으로 동작되어야 한다 고전압펄스전원장치는 바이어스 전압이 영부터 -1.5 kV사이를 연속적으로 가변 할 수 있어야 하고, 펄스의 반복 주파수는 CW로 부터 1 kHz 그리고 펄스폭은 $10\;{\mu}s$부터 $500\;{\mu}s$로 선택 가능하여야 한다. 그리고 출력펄스의 상승 및 하강 시간은 150 ns 보다 작아야 한다. 턴-온 및 오프의 스윗칭 시간을 만족시키기 위하여 고전압 스위치는 직렬로 연결된 FET 모듈을 사용하였다. 본 논문에서는 이러한 고전압 펄스전원장치의 설계 및 제작원리 그리고 시험결과에 대하여 다루었다.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1205-1207
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• 2003

고전압 전원공급기를 고 밀도로 제작하기 위하여 고 주파수 동작을 시켜야 한다. 이에 따라 전원 공급기에서 최대의 부피를 차지하는 부품인 변압기는 원하는 주파수에서 최소의 부피로 충분한 전력을 수강하면서 완벽한 펄스재현을 하여야 한다. 그리고 승압비를 일정수준으로 유지하여야 한다. 이러한 변압기의 설계 및 제작 시 주의하여야 한다. 진행파관 증폭기용 고밀도 고전압전원공급기용 고주파수, 고전압, 펄스 변압기 변압기를 설계, 제작 시험하였다. 변압기의 스윗칭 주파수는 80 kHz 이며 입력전압은 265 Vdc이고 출력전압은 4kVdc 이다. 변압기의 정상 출력은 1.7 kW이다. 그리고 최대부피는 $200\;cm^3$ 이하가 되어야 한다. 본 논문에서는 다양한 권선 방법에 의하여 제작된 변압기에 대하여 변압기의 설계 및 시험절차가 제시되었다. 그리고 변압기의 누설 인덕턴스, 분포 케페시턴스 및 공진 주파수도 측정하여 평가하였다.

• The Korean Journal of Malacology
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• v.17 no.2
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• pp.71-78
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• 2001

Age and growth of the pen shell, Atrina (Servatrina) pectinata japonica, on the west coast of Korea were studied based on 701 samples caught in April 1995 to March 1996. The results are summarized as follows: the relationship between shell height and ring radius in each ring group was expressed as a regression line. Therefore, it could be recognized that there is a correspondence in the formation of each ring. Based on the monthly variation of the marginal index (MI') of the shell, it was assumed that the ring of this species was formed once a year during the period of June to July. The relationship between shell height (SH) and total weight (TW) were expressed by the following equation TW = 5.906$\times$10/$^{-3}$SH$^{3.844}$. Shell length (SL) and shell height were highly correlated according to the following equation SL = 0.5277 SH +0.0934. The shell height-shell width (SW) relation was expressed by the following equation SW = 0.2681 SH -1.3757. Growth curves for shell height and total weight fitted to the von Bertalanffy's equation were expressed as: SHt=30.99(1-e-$^{-0.3212(t+0.9653)}$, TWt=657.94(1-e-$^{-0.3212(t+0.9653}$)$^{3.3844}$.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.493-496
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• 2007

Korean Institute of Geosciences and Mineral Resources (KIGAM) has studied on gas hydrate in the Ulleung Basin, East sea of Korea since 1997. Most of all, a evidence for existence of gas hydrate, possible new energy resources, in seismic reflection data is bottom simulating reflection (BSR) which parallel to the sea bottom. Here we conducted the conventional data processing for gas hydrate data and Kirchhoff prestack depth migration. Kirchhoff migration is widely used for pre- and post-stack migration might be helpful to better image as well as to get the geological information. The processed stack image by GEOBIT showed some geological structures such as faults and shallow gas hydrate seeping area indicated by strong BSR. The BSR in the stack image showed at TWT 3.07s between shot gather No 3940 to No 4120. The estimated gas seeping area occurred at the shot point No 4187 to No 4203 and it seems to have some minor faults at shot point No 3735, 3791, 3947 and 4120. According to the result of depth migration, the BSR showed as 2.3km below the sea bottom.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.3
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• pp.162-168
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• 1991

Iterbicide resduc. cauicd ~rljul-y to ovcrsown pasture grasses \\hen herbicide appliccl for use in pasturc est;~blish~nt~nt lo gro~vth contro! ol n;rtivc ~r ~:cds and shrubs. 'l'hih L~sperirnel~t was conducted to cv;lluati. (he herbicidr residue anti its ph!:totosical ~riiiuence on the growth of introtluccd pasturts species. Esperimcmtal soils was treated with buthitlazolc, ~ o d l ~ l m chlorate, glyphosatc. U-46 anti paraquat each at twt) applici~tion rates. Lhcf~1i.s glowl~mlc~ including othrr pasture grasses and le~urnes were evaluatrd for tolerance to herbicide. IIerbicide residue in the amount ot injury caused to introduced pasture grasses was found in order of buthidazole, sodium chlorate, U-46 and glyphosate. Euthidazole was not available for use in pasture establishment because of their long persist of toxic herbicide residues. A great stand redl~ction of subseq ~ ~ c n t oversown pastures was also observed In sodium chlorate treatment. However, normal vegetative stand and grass production was obtained, when thc pasture grasses seeded 45-60 days later herbicide treatments. Glyphosate did not affect subsequent oversown pasture species in both grasses and legumes. fistuccr arundinc~cea and Pou pratensis were the most tolerant pasture species to herbicide residue while 7'rzfi,lium pyatense and Medicugo suti~u showed a wsceptible response regardless of herbicide.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.5
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• pp.7-14
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• 1977

Conventionally, a TIVT has been used for high power amplification in the microwave frequency range. However, an ultra-high-power amplifier in the 2GHz range has successfully been designed and fabricated employing high power transistors developed recently and available commercially. In the design of the amplifier, a balanced-pair configuration is adopted in order to obtain very high microwave power, and a good impedance matching is achieved by making use of microstripline techniques. For the RF power divider as well as combiner, an approach of stripline directional coupler isadopted because of its easiness in fabrication. The coupler so designed and fabricated indicates a satisfactory performance as a quadrature hybrie coupler. Measurements on the amplifier developed for an immediate commercial application also exhibit excellent overall performance characteristics RF power output, 14 watts, gain 14dB, frequency bandwidth, 160MHz, effciency 40%.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.208-212
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• 2008

Gas hydrate has been paid attention to study for because: 1) it can be considered as a new energy resources; 2) one of reasons causing the instability of sea floor slope and 3) a factor to the climate change. Bottom simulating reflector (BSR) defined as seismic boundary between the gas hydrate and free gas zone has been considered as the most common evidence in the seismic reflection data for the gas hydrate exploration. BSR has several characteristics such as parallel to the sea bottom, high amplitude, reducing interval velocity between above and below BSR and reversing phase to the sea bottom. Moreover, instantaneous attribute properties such as amplitude envelop, instantaneous frequency, phase and first derivative of amplitude of seismic data from the complex analysis could be used to analyze properties of BSR those would be added to the certain properties of BSR in order to effectively find out the existence of BSR of the gas hydrate stability zone. The output of conventional seismic data processing for gas hydrate data set in Ulleung basin in the East sea of Korea will be used for complex analyses to indicate better BSR in the seismic reflection data. This result of this analysis implies that the BSR of the analyzed seismic profile is clearly located at the two ways time (TWT) of around 3.1 seconds.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1329-1336
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• 1998

A twt -step carbothermal reduction scheme has been employed for the synthesis of SiC whiskers in an Ar or a H2 atmosphere via vapor-solid two-stage and vapor-liquid-solid growth mechanism respectively. It has been shown that the whisker growth proceed through the following reaction mechanism in an Ar at-mosphere : SiO2(S)+C(s)-SiO(v)+CO(v) SiO(v)3CO(v)=SiC(s)whisker+2CO2(v) 2C(s)+2CO2(v)=4CO(v) the third reaction appears to be the rate-controlling reaction since the overall reaction rates are dominated by the carbon which is participated in this reaction. The whisker growth proceeded through the following reaction mechaism in a H2 atmosphere : SiO2(s)+C(s)=SiO(v)+CO(v) 2C(s)+4H2(v)=2CH4(v) SiO(v)+2CH4(v)=SiC(s)whisker+CO(v)+4H2(v) The first reaction appears to be the rate-controlling reaction since the overall reaction rates are enhanced byincreasing the SiO vapor generation rate.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.7-14
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• 2019

PURPOSE: This study examined the effects of observing a self-video or a video of another person performing balance and gait training, followed by actual performance of the observed movements on the balance and walking ability of chronic stroke patients. METHODS: Thirty patients, who had experienced a stroke and were admitted to S rehabilitation hospital for treatment, were selected randomly and divided into three groups with 10 patients each: self-action observation (SAO) group, other-action observation (OAO) group, and treadmill walking training (TWT) group. The training program was conducted five times per week for four weeks. The GAITRite system, 10 m walking test, and timed up and go test were performed to measure the subjects' gait and balance ability. RESULTS: The velocity, cadence, double support, and stride length were increased significantly in the SAO and OAO groups (p<.05) but the T group showed no significant changes; no significant difference was observed among the groups (p >.05). The 10MWT decreased significantly in the OAO group (p<.05), but there were no significant changes in the SAO and T groups, and no significant difference was observed among the groups (p>.05). The TUG decreased significantly in the SAO and OAO groups (p<.05), but there were no significant changes in the T group, and no significant difference was observed among the groups (p>.05). CONCLUSION: The self or other action observation training helps improve the balance and gait ability.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.24-33
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• 2002

Objectives: Nasal continuous positive airway pressure (CPAP) corrected elevated blood pressure (BP) in some studies of obstructive sleep apnea syndrome (OSAS) but not in others. Such inconsistent results in previous studies might be due to differences in factors influencing the effects of CPAP on BP. The factors referred to include BP monitoring techniques, the characteristics of subjects, and method of CPAP application. Therefore, we evaluated the effects of one night CPAP application on BP and heart rate (HR) reactivity using non-invasive beat-to-beat BP measurement in normotensive and hypertensive subjects with OSAS. Methods: Finger arterial BP and oxygen saturation monitoring with nocturnal polysomnography were performed on 10 OSAS patients (mean age $52.2{\pm}12.4\;years$; 9 males, 1 female; respiratory disturbance index (RDI)>5) for one baseline night and another CPAP night. Beat-to-beat measurement of BP and HR was done with finger arterial BP monitor ($Finapres^{(R)}$) and mean arterial oxygen saturation ($SaO_2$) was also measured at 2-second intervals for both nights. We compared the mean values of cardiovascular and respiratory variables between baseline and CPAP nights using Wilcoxon signed ranks test. Delta ($\Delta$) BP, defined as the subtracted value of CPAP night BP from baseline night BP, was correlated with age, body mass index (BMI), baseline night values of BP, BP variability, HR, HR variability, mean $SaO_2$ and respiratory disturbance index (RDI), and CPAP night values of TWT% (total wake time%) and CPAP pressure, using Spearman's correlation. Results: 1) Although increase of mean $SaO_2$ (p<.01) and decrease of RDI (p<.01) were observed on the CPAP night, there were no significant differences in other variables between two nights. 2) However, delta BP tended to increase or decease depending on BP values of the baseline night and age. Delta systolic BP and baseline systolic BP showed a significant positive correlation (p<.01), but delta diastolic BP and baseline diastolic BP did not show a significant correlation except for a positive correlation in wake stage (p<.01). Delta diastolic BP and age showed a significant negative correlation (p<.05) during all stages except for REM stage, but delta systolic BP and age did not. 3) Delta systolic and diastolic BPs did not significantly correlate with other factors, such as BMI, baseline night values of BP variability, HR, HR variability, mean SaO2 and RDI, and CPAP night values of TWT% and CPAP pressure, except for a positive correlation of delta diastolic pressure and TWT% of CPAP night (p<.01). Conclusions: We observed that systolic BP and diastolic BP tended to decrease, increase or remain still in accordance with the systolic BP level of baseline night and aging. We suggest that BP reactivity by CPAP be dealt with as a complex phenomenon rather than a simple undifferentiated BP decrease.