• Investigative Magnetic Resonance Imaging
• /
• 제22권1호
• /
• pp.26-36
• /
• 2018

Purpose: Children born with single ventricle physiology demonstrate poor growth rate and suffer from malnutrition, which lead to increased morbidity and mortality in this population. We assume that an anabolic steroid, oxandrolone, will promote growth in these infants by improving myocardial energy utilization. The purpose of this paper is to study the efficacy of oxandrolone on myocardial energy consumption in these infants. Materials and Methods: We modeled single ventricle physiology in a lamb by prenatally shunting the aorta to the pulmonary artery and then postnatally, we monitored cardiac energy utilization by quantitatively measuring the first order reaction rate constant, $k_f$ of the creatine-kinase reaction in the heart using magnetization transfer $^{31}P$ magnetic resonance spectroscopy, home built $^1H/^{31}P$ transmit/receive double tuned coil, and transmit/receive switch. We also performed cine MRI to study the structure and dynamic function of the myocardium and the left ventricular chamber. The spectroscopy data were processed using home-developed python software, while cine data were analyzed using Argus software. Results: We quantitatively measured both the first order reaction rate constant and ejection fraction in the control, shunted, and the oxandrolone-treated lambs. Both $k_f$ and ejection fraction were found to be more significantly reduced in the shunted lambs compared to the control lambs, and they are increased in oxandrolone-treated lambs. Conclusion: Some improvement was observed in both the first order reaction rate constant and ejection fraction for the lamb treated with oxandrolone in our preliminary study.

• 한국자기학회지
• /
• 제11권5호
• /
• pp.222-225
• /
• 2001

1W급의 DC-DC converter에 탑재하기 위해 FeTaN 연자성 자성박막을 이용한 박막형 인덕터를 제조하여 특성을 평가하였다. 자심부분은 2$\mu\textrm{m}$ 두게의 F $e_{78.81}$T $a_{8.47}$ $N_{12.71}$ 연자성 박막을 사용하였으며 코일부분은 100$\mu\textrm{m}$ 두게의 Cu를 사진공정과 전기도금공정을 이용하여 제조하였다. 제조된 박막 인덕터의 디자인은 상호인덕턴스를 효율적으로 증가시킬 수 있는 double rectangular spiral형태였으며 측정된 특성은 DC-DC converter의 작동주파수인 1 MHz에서 인덕턴스 980nH, 저항 1.7 $\Omega$Q 값은 3.55였다.다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
• /
• pp.407-410
• /
• 2002

As a part of electro-mechanical totally implantable artificial heart, a transcutaneous energy transmission system has been developed. By mutual magnetic induction between the first coil on the skin and the subcutaneously implanted second coil, the system transfers electrical power through the skin. This research aimed a minimizing the size of the implanted part as well as maximizing the transfer efficiency. When an air gap is 1$\sim$2cm, voltage gain and current gain low and it is hard to transfer energy due to large leakage flux. That is, the required input voltage and input current must be large compared with the output voltage and output current, respectively, This paper research the inverter topology and the control method in order to increase the voltage gain and the current gain. For this purpose, this inverter employs double tune to compensate the large leakage inductance of primary and secondary of the transcutaneous transformer. And the output energy of transcutaneous energy transmission system supply for Lithium-ion battery charger.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2003년도 학술대회 논문집
• /
• pp.123-125
• /
• 2003

We joined 19-multifilamentary (Bi, Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$_{x}$ Superconducting tapes and fabricated double-pancake coils by using resistive- and superconducting-joint methods. The joint resistance of the coils were characterized by the field decay technique and standard four-probe method. It was evaluated that joint resistance was 3.21$\times$10$^{-11}$ $\Omega$ in the superconducting-joint coil, which is approximately 4 orders of magnitude smaller than that in the resistive-joint coil (107$\times$10$^{-9}$ $\Omega$). The low value of joint resistance obtained by superconducting-joint is expected to be suitable for the practical applications in the persistent current mode.e.

• 대한조선학회논문집
• /
• 제35권1호
• /
• pp.98-106
• /
• 1998

멤브레인형 가스운반선의 경우 화물창들 사이에 cofferdam을 두어 격리시키고 있는데 이 경우 극 저온 액체 화물의 영향으로 cofferdam 실내 온도는 약 $-40^{\circ}C$내외로 떨어지게 된다. 그 결과 cofferdam 및 화물창을 구성하는 bulkhead는 구조 부재로서의 허용 강도를 만족하는 온도를 유지할 수 없게 된다. 결국 heating system을 사용하여 cofferdam 실내 온도를 최소한 $5^{\circ}C$까지 올려야 하는데, 소요 pipe의 길이 산정을 위한 heat flux 산출과 pipe의 배치가 우선적으로 요청된다. 본 연구에서는 다양한 설계 조건에서의 cofferdam 내 heat flux를 각 compartment들 간의 연성 효과를 고려하여 구하고 이를 기존 계산서들과 비교 검토하여 그 타당성을 검증하였고 이를 토대로 heating system에 필요한 pipe의 길이를 산정하였다. 아울러 현재의 heating system의 대안으로 fin을 부착한 pipe로 구성된 heating coil system을 제시하고 그 효율을 비교하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.233-234
• /
• 2007

We investigated the quench characteristics in integrated three-phase flux-lock type superconducting fault current limiter (SFCL), which consisted of three-phase flux-lock reactor wound on one iron core with the same turn's ratio between coil 1 and coil 2 for each single phase. To study the quench characteristics of the SFCL, the experiments was performed on various fault type such as the single line-to-ground fault, the double line-to-ground fault, the triple line-to-ground fault. From the experimental results, the generated point of element resistances was different on various fault type.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.39-40
• /
• 2007

The analysis of fault current limiting characteristics according to variation of fault current level in the integrated three-phase flux-lock type superconducting fault current limiter (SFCL), which consisted of three-phase flux-lock reactor wound on an iron core with the same turn's ratio between coil 1 and coil 2 for each single phase, was performed. To analyze the current limiting characteristics of this integrated three-phase flux-lock type SFCL, the short circuit experiments was carried out the various three-phase faults such as the single line-to-ground fault, the double line-to-ground fault, the triple line-to-ground fault. From the experimental results, the fault current limiting characteristic was improved according to increase of fault current level.

• 한국정보통신학회논문지
• /
• 제13권8호
• /
• pp.1491-1496
• /
• 2009

본 논문에서는 비상 디젤 엔진 발전기 제어 및 모니터링을 위해 제안된 디지털 기반의 입/출력 인터페이스 회로를 소매한다. 비상 발전기의 동작 상태를 모니터링 하고 제어하기 위해 제어 및 감시 회로는 5개의 아날로그 입력 채널과 2개의 픽업(Pick-up)코일 계측 회로, 브로컨 와이어(Broken Wire) 감지 기능을 가지는 10개의 디지털 입력 채널 및 7개의 릴레이 제어 신호 출력 채널이 요구된다. 본 연구에서는 아날로그 입력 단에 간단한 필터 회로와 포토커플러, 비교기 회로를 이용하여 입력 신호에 대한 신호처리를 수행하였으며, 중요한 릴레이 출력 신호들은 이중으로 단속될 수 있도록 설계하여 오동작을 철저히 방지하였다. 그리고 픽업코일 신호를 디지털 처리하는 회로를 적용하여 속도 신호 입력의 정확성을 향상 시켰다.

• Journal of Korean Neurosurgical Society
• /
• 제60권2호
• /
• pp.262-268
• /
• 2017

Objective : Stents are widely used in coil embolization of intracranial aneurysms, but on occasion, a microcatheter must traverse a stented segment of artery (so-called trans-cell technique) to select an aneurysm, or double stenting may necessary. In such situations, microguidewire passage and microcatheter delivery through a tortuous stented parent artery may pose a technical challenge. Described herein is a microguidewire looping technique to facilitate endovascular navigation in these circumstances. Methods : To apply this technique, the microguidewire tip is looped before entering the stented parent artery and then advanced distally past the stented segment, with the loop intact. Rounding of the tip prevents interference from stent struts during passage. A microcatheter is subsequently passed into the stented artery for positioning near the neck of aneurysm, with microguidewire assistance. The aneurysm is then selected, steering the microcatheter tip (via inner microguidewire) into the dome. Results : This technique proved successful during coil embolization of nine saccular intracranial aneurysms (internal carotid artery [ICA], 6; middle cerebral artery, 2; basilar tip, 1), performing eight trans-cell deliveries and one additional stenting. Selective endovascular embolization was enabled in all patients, resulting in excellent clinical and radiologic outcomes, with no morbidity or mortality directly attributable to microguidewire looping. Conclusion : Microguidewire looping is a reasonable alternative if passage through a stented artery is not feasible by traditional means, especially at paraclinoid ICA sites.

• Progress in Superconductivity
• /
• 제13권1호
• /
• pp.1-6
• /
• 2011

Measurement of magnetic signals generated from electric activity of myocardium provides useful information for the functional diagnosis of heart diseases. Key technical component of the magnetocardiography (MCG) technology is SQUID. To measure MCG signals with high signal-to-noise ratio, sensitive SQUID magnetic field sensors are needed. Present magnetic field sensors based on Nb SQUIDs have field sensitivity good enough to measure most of MCG signals. However, for accurate measurement of fine signal pattern or detection of local atrial fibrillation signals, we may need higher field sensitivity. In addition to field sensitivity, economic aspect of the SQUID system is also important. To simplify the SQUID readout electronics, the output voltage or flux-to-voltage transfer of SQUID should be large enough so that direct measurement of SQUID output can be done using room-temperature preamplifiers. Double relaxation oscillation SQUID (DROS), having about 10 times larger flux-to-voltage transfers than those of DC-SQUIDs, was shown to be a good choice to make the electronics compact. For effective cancellation of external noise inside a thin economic shielded room, first-order axial gradiometer with high balance, simple structure and long-baseline is needed. We developed a technology to make the axial gradiometer compact using direct bonding of superconductive wires between pickup coil and input coil. Conventional insert has mechanical support to hold the gradiometer array, and the dewar neck has equal diameter with the dewar bottom. Boiling of the liquid He can generate mechanical vibrations in the gradiometer array due to mechanical connection structure. Elimination of the mechanical support, and direct mounting of the gradiometer array into the dewar bottom can reduce the dewar neck diameter, resulting in the reduction of liquid He consumption.