• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.5
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• pp.382-390
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• 2017

In this paper, we consider particular exposure scenarios to evaluate human effects for inductive commercial wireless charging device operating at low frequency. The coil used in this study is the A10 model in Qi standard proposed by WPC(Wireless Power Consortium), and input power is 5 W to the operating frequency of 155 kHz. In perfectly aligned condition, the max leakage magnetic field is $257.58{\mu}T$ which is obtained at the side of the device, and it is exceeded about 7.4 times of the ICNIRP 1998 reference level. The SAR is evaluated with homogeneous phantom which has electric constants of wet skin. The max value of the SAR is $134.47{\mu}W/kg$ which is obtained at the side of the device also, and it is much lower than the international guidelines. Especially, it showed higher SAR values in case of misalignment condition, so we will need to consider the misalignment condition importantly when we evaluate human effects for wireless power transfer system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.933-940
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• 2017

A wireless power transfer system with a negative impedance converter(NIC) was designed and tested. The system was investigated to identify the effects of ferrites and conductors. To improve the power transfer efficiency(PTE), the Q-factor of the transmitter was enhanced by the negative resistance generated by the NIC. The NIC was composed of an Op-Amp and resistors. The negative resistance was obtained with respect to a resistor connected in a feedback loop. The dimension of the Tx coil was $250mm{\times}250mm{\times}0.8mm$. The impedance and Q-factor were $31+j1874{\Omega}$ and 60, respectively. The negative resistance was selected to be $30{\Omega}$, and the Q-factor was increased to 900 by reduction of the transmitter resistance, which was about 15 times higher than that of a conventional transmitter. The measured PTE was greatly improved in comparison to that of a conventional system. These results demonstrate that the PTE is enhanced by using the NIC.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.106-106
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• 2014

SIGMA (Scientific cubesat with Instrument for Global Magnetic field and rAdiation)는 근 지구공간에서 우주방사선량 측정과 자기장 변화 검출의 과학적 목적과 교육적 목적을 가지고 개발하고 있는 초소형 큐브위성이다. $100mm{\times}100mm{\times}340.5mm$의 크기로 약 3.6 kg의 무게를 가지며, 탑재체는 방사선에 대하여 인체와 동일한 산란 흡수 특성을 가진 Tissue Equivalent Proportional Counter (TEPC)와 자기장 측정을 위한 Magnetometer (Mag)이다. 위성체는 구조계, 자세제어계, 전력계, 명령 및 데이터처리계, 통신계로 구성되어있다. 구조계는 위성의 뼈대인 Chassis와 Mag deployer로 이루어져있고, 위성의 안정적인 자세유지를 목적으로 Attitude Control System (ACS) Board와 Torque Coil이 자세제어계로 구성된다. 전력의 생산과 공급 및 충전은 태양전지판과 Electrical Power System (EPS), 리튬 배터리로 구성된 전력계에서 이뤄지며, 명령 및 데이터처리계는 On Board Computer (OBC)와 Instrument Interface board (IIB)를 중심으로 서브시스템의 명령체계와 데이터처리를 다룬다. 통신계는 Uplink인 VHF 안테나와 Downlink인 UHF, S-band 안테나로 구성되며 지상과 명령을 송수신한다. SIGMA는 타임인터럽트 기능을 활용한 Flight Software (FSW)로 운용되며 임무에 따른 6가지 모드의 시나리오로 위성을 운용한다. 이에 SIGMA의 개발과 테스트 결과를 소개한다. 본 큐브위성 개발기술을 바탕으로 향후 천문관측용 위성에도 활용할 예정이다.

• Journal of Korean Academy of Nursing
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• v.2 no.1
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• pp.141-157
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• 1971

The peripheral infection is one of the major causes of maternal death, and although it is preventable through an effective prenatal as well as postnatal care its morbidity is increasing due to bacterial resistant to an effective antibiotics. The primary purpose of this study was to investigate the peripheral morbidity of 949 parturients who were admitted to the Obstetrics and Gynecologic department of Ewha Woman's University Hospital from January 1971 to September 1971. Among the 949 parturients, especially 40 normal parturients were selected (20, control soup was given complete aseptic care during labor and delivery and post delivery: 20, compare group was given the ordinary care practiced during labor and delivery and maternal ward of Ewha Woman's University Hospital) for bacteriologic test on vaginal flora twice, on admission and on complete cervical dilatation of each parturient. The results obtained from this study were as follows; 1. Majority of parturients age were 21 to 35 years old(90.83%), and educational level of 949 parturients was above high school. A large number of parturients socioeconomic level (according to their husbands' job) were moderate. 2, Among the 949 parturients, multipara (55.9%) were a little more than primipara (44. 1%) and 38.84% of parturients had experienced aborition. 3. In deliverty types, normal deliveries (804 cases) were more than cesarean section deliveries (145 cases) The peripheral morbidity after normal deliveries was 0.5%, and cesarean section deliveries, 23.45%. 4. Among 949 parturients incidence of hemorrhage eases (500cc or more bleeding) showed the higher peripheral morbidity (24.86%) than other cases (bleeding less than 500cc, 7.83%). 5. The majority of parturients (81.03%) had teen taking antenatal care, but most of them were taken irregular antenatal care. On the other hand, on admission, the parturients with complication were 30.32%, and their peripheral morbidity showed much higher (7.02%) than those with no complication (2.71%). 6. The incidence of peripheral morbidity in premature ruptured membrane was higher (10.91%) than normal parturienta (1.73%). 7. In the result of aseptic care during labor and delivery and post delivery, the number of cultured bacteria was legs in control group than Compare group (in control group, on admission 17, on complete cervical dilatation 12: in compare group, on admission 21 on complete cervical dilatation 21) . The most common bacteria were Staphylococcus (control group 14 on admission, compare group 16 on admission), and next Streptococcus, E- Coil, Bacillus Subtilis, in order. Also in control group the number. of colony were reduced (43%) more than in Compare group. Transient temperature elevation from 37℃ to 37.4℃ were noted in compare group (50%) than in control group (30%), and there was no one indicated above 38℃. In conclusion, the aseptic care is the test way of preventing peripheral infection as well as decreasing the puerperal morbidity. Therefore the most important nursing care is the aseptic care for each parturient during labor and delivery and peat delivery and also all the instruments must be cleaned and sterilized.

• 전기의세계
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• v.43 no.1
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• pp.13-19
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• 1994

전자식 안정기는 최근 에너지 절약 정책과 관련하여 조명기기분야의 관심의 대상이 되었고, 절전 효율이 높은 고품질의 전자식 안정기에 대한 연구 개발 및 보급이 점점 더 확대되고 있는 추세이다. 일반적으로 전자식 안정기는 수십 KHz의 고주파에서 형광등을 구동시킴으로써 빛의 깜박거림과 가청잡음이 없으며, 저주파(60Hz)에서 사용하는 재래식 안정기(choke coil 방식)에 비해 높은 절전 효과를 얻을 수 있다[1-4]. 특히, 빌딩 사무실의 경우 낮에도 창가의 형광등이 켜져 있어서 막대한 전력을 낭비하고 있는 실정이므로, 일조량에 따른 자동 전력 조절이 가능한 전자식 형광등의 출현이 기대되고 있다. 전자식 안정기의 보급 확대를 위해서는 절전 효과 뿐만 아니라, 품질 문제, 수명 문제등을 고려하여야 하는 바, 예를 들면 순간 점등으로 방전초기의 sputtering 현상에 의한 lamp의 수명 단축, 미소 입력전압 변동에 따른 급격한 광출력의 변화로 절전 효과의 상실과 이상동작에 의한 스위칭 소자의 파괴 현상, 고주파 스위칭시 발생되는 전력손실과 noise등에 대한 대책이 요구되고 있다. 이러한 점을 개선하기 위해 추가되는 회로는 전자식 안정기 시스템을 더욱 복잡하게 만들고, 경제적으로 원가 부담을 주기 때문ㅇ 고품질의 전자식 안정기를 보급하는데 어려운 점으로 부각되고 있다. 본 고에서는 이러한 문제를 해결하기 위하여 조광기능을 포함한 다양한 제어회로와 보호회로를 조광기능을 포함한 다양한 제어회로와 보호회로를 1 chip에 수용하는 고품질의 전자식 안정기 제어용 집적회로에 대해서 기술하고자 한다.되어 나아갈 기술의 조류에도 부합하는 형태라 하겠다. 그러나 이 방식은 기 언급한 바와 같이 분산처리를 관장하는 운영체계의 개발에 상당한 고전이 따르리라 보여지며, 또한 보다 상세한 연구가 선행되어야 하겠지만 개발된 상용의 통신 프로토콜로서는 병렬처리의 성능을 극대화 하기에는 여러가지 제약이 있을 것으로 예측된다.기기들이 어떻게 응용되고 있는지 살펴보기로 하자. real informations would be available. Results are compared with those of optimal power flows.기능시험을 완료했으며 실제 line-of-sight(LOS) 시스템 구현에 적용중이다. 시대를 살아 갈 회원들이다. '컨텐츠의 시대'가 개막되는 것이며, 신세기통신과 SK텔레콤은 선의의 경쟁 과 협력을 통해 이동인터넷 서비스의 컨텐츠를 개발해 나가게 될 것이다. 3배가 높았다. 효소 활성에 필수적인 물의 양에 따른 DIAION WA30의 라세미화 효율에 관하여 실험한 결과, 물의 양이 증가할수록 그 효율은 감소하였다. DIAION WA30을 라세미화 촉매로 사용하여 아이소옥탄 내에서 라세믹 나프록센 2,2,2-트리플로로에틸 씨오에스터의 효소적 DKR 반응을 수행해 보았다. 그 결과 DIAION WA30을 사용하지 않은 경우에 비해 반응 전환율과 생성물의 광학 순도는 급격히 향상되었다. 전통적 광학분할 반응의 최대 50%라는 전환율의 제한이 본 연구에서 찾은 DIAION WA30을 첨가함으로써 성공적으로 극복되었다. 또한 고체 염기촉매인 DIAION WA30의 사용은 라세미화 촉매의

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.197-203
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• 2014

The safety and arming device(SAD), one of the components of the fuzes, shall provide safety that is consistent with handling, storage, transportation, use, and disposal. In this paper, we describes the design of the SAD which includes the solenoid assembly and the solenoid driving circuit to improve the safety of the fuzes. The solenoid assembly consists of a coil assembly, a restoring spring, and a core. The solenoid assembly is added in the SAD as an additional safety device. In case of the normal circumstances, the core of the solenoid assembly restrains the $1^{st}$ and $2^{nd}$ safety devices of the SAD for those devices not to operate at all, so that the SAD can secure safety for storage, transportation, and use. In contrast, when the battery power is provided to the solenoid driving circuit just before the flight, the core confirms the power level and starts removing the restraint from the $1^{st}$ and $2^{nd}$ safety devices of the SAD, and then the SAD is able to change its mode from safety mode to armed mode. After firing, once the SAD's operations complete, the turned-on arming switch stops providing the power to the solenoid assembly automatically. It can reduce the power consumption at solenoid assembly. Therefore, the proposed solenoid driving circuit for the solenoid assembly not only unlocks the restrained solenoid assembly from the safety devices, but also saves the power consumption during the flight.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.6
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• pp.684-689
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• 2007

The aim of this study is to examine the change of the osteoclastic activity in the surrounding bone with or without tooth movement after corticotomy by histologic study. Eighteen male Sprague Dawley rats with an average body weight of 300 g(range 250-350 g) were used. The rats were divided into three groups of six animals. They were operated corticotomy-assisted tooth movement and killed after 1 week, 2 weeks, and 3 weeks after tooth movement. Corticotomy was done in the surrounding of the both upper first molar. A split mouth design was used by referring to the contralateral side as control. After flap suturing, the upper left first molar was moved anteriorly by closed coil spring. The force applied was 1 N. The average of tooth movement of the 1 week group was $0.24{\pm}0.09mm,\;0.20{\pm}0.26mm$ in 2 weeks group and $0.41{\pm}0.39mm$ in 3 weeks group, respectively. The difference between the 1 week and the 2 weeks groups was very small to compare with the 3 weeks group. In the treatment group, the average numbers of cells that positively reacted to TRAP were 14.5 in the 1 week group, 12.0 in the 2 weeks group, and 6.0 in the 3 weeks group. In the control group, the numbers were 8.3 in the 1 week group, 12.8 in the 2 week group, and 1.5 in the 3 week group, respectively. The amount of tooth movement of the 3 week group was about twice as large as those of the 1 week and 2 week groups. From the standpoint of histology, the average number of cells that positively reacted to TRAP was initially larger in the treatment group than in the control group, similar in both group in 2 weeks, and became less in the treatment group in 3 weeks. Additionally, in the control group, their activity of osteoclast was higher in 2 weeks than in 1 week, and decreased rapidly in 3 weeks.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.137-137
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• 2001

Purpose： The purpose of this study was to identify cerebral cortices related with sexual arousal fro visual sexual stimulation in healthy males using BOLD-based functional MR imaging Method： Sixteen male volunteers with sexually potent(mean age：24) were examined for thi study. Functional MRI was performed on a 1.5T MR scanner(GE Signa Horizon) with birdcage-type head coil. In this study, blood oxygenation level dependent(BOLD) technique was utilized to create fMR image reflecting local brain activities. The BOLD-based fMRI d were obtained from 7 oblique planes using gradient-echo EPI with $90^{\circ}$flip angle, 50ms TE 6000ms TR, $26cm{\times}26$ cm FOV, $128{\times}128$ matrix, and 10mm slice thickness. The sexual stimulation paradigm consisted of two alternating periods of rest and activati and it began with a 1 minute rest, followed by a 2 minute stimulation by a documentary a erotic video film. Brain activation maps were generated by cross-correlation of imag acquired during rest and activation periods. The index of activation was used to compare t number of pixels activated by each task in each volunteer, where the significance of th differences was evaluated by using Students t-test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1075-1081
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• 2010

Recently, the results of many studies have clarified the successful performance of magnetostrictive transducers in which a ferromagnetic patch is used for the transduction of guided shear waves; this is because a thin ferromagnetic patch with strong magnetostriction is very useful for generating and detecting shear wave. This investigation deals with bulk shear wave transduction by means of magnetostriction; on the other hand, the existing studies have been focused on guided shear waves. A modular transducer was developed; this transducer comprised a coil, magnets, and a thin ferromagnetic patch that was made of Fe-Co alloy. Some experiments were conducted to verify the performance of the developed transducer. Radiation directivity pattern of the developed transducer was obtained, and a test to detect the damage on a side drill hole of a steel block specimen was carried out. From the results of these tests, the good performance of the transducer for nondestructive testing was verified on the basis of the signal-to-noise ratio and narrow beam directivity.

• Journal of the Korean Society of Radiology
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• v.9 no.5
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• pp.307-314
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• 2015

This study was conducted in reducing the involuntary motion artifacts because of lungs and heart movements as well as the aliasing artifacts generated during the use of the reduced-FOV EPI technique while performing breast MRI. Performed on a total of 38 obesity female subjects who visited the clinic for pre-examination before surgery within the period from August 1 to November 30, 2014. The 3.0T MRI scanner equipped with a breast scanning coil. Qualitative and quantitative analyses were each used for the evaluation of the acquired images while an Paired T-test and Wilcoxon rank test were performed to check the statistical significance. The variation ratio rose by 15.69% with the additional application of a pre-saturation pulse in the lesion, by 13.72% near the lesion, and 20.63% in the fat and the contrast-to-noise ratio rose by 10.58% in and near the lesion and by 12.03% in the lesion and fat, respectively. there were increases of 22.05% and 21.42% at 0 and 1000 respectively in qulitative evaluation and growth of 16.10% in apparent diffusion coefficient. it showed a statistically significant result(p<0.05) in signal to noise ratio, contrast to noise ratio, diffusion slope coefficient and apparent diffusion coefficient. The involuntary movements artifacts that occur in the phase encoding direction and the aliasing artifacts are considered to be reduced to obtain the best image in the additional use of the pre-saturation pulse as DWI is acquired.