• 대한전자공학회논문지SD
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• 제48권10호
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• pp.1-5
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• 2011

근접 통신 시스템(NFC)의 전력 전송 효율과 수동형 RFID의 동작 거리 향상을 위해 자기 공명 공진코일을 이용한 무선전력전송 방식을 근접 통신 단말에 적용하였다. 소스코일과 디바이스코일 사이에 공진코일을 배치시켜 시스템을 구성하였으며, 효율을 13.56MHz 대역의 RFID 리더와 태그 시스템을 사용하여 측정하였고, 3차원 시뮬레이터를 통하여 시뮬레이션 하였다. RFID 리더와 태그를 통해 측정한 결과, 자기 공명 공진코일을 적용한 경우 신호의 송수신 최대 거리는 96.72%, RFID 태그의 수신된 전압은 17.95% 증가함을 보였다.

• 한국콘텐츠학회논문지
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• 제12권7호
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• pp.247-254
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• 2012

본 연구는 2010년 3월부터 2011년 9월까지 뇌동맥류로 H병원에 내원한 환자 중 혈관조영술을 시행하여 코일 색전술을 받은 53명의 환자를 대상으로 뇌동맥류의 체적에 따른 코일의 길이 특성을 평가하였다. 뇌동맥류에 대한 색전술을 시행한 환자의 뇌동맥류에 대하여 볼륨렌더링기법으로 체적을 구하였으며, 코일색전술을 실시한 후 코일의 체적 및 길이를 구하여 체적율을 계산하였다. 뇌동맥류의 크기에 따른 색전체적율은 6mm 이하에서는 $43.11{\pm}3.11%$, 6~10mm에서는 $36.07{\pm}2.03%$, 10~15mm 이상은 40.91%, 20mm 이상에서는 38.25%를 나타내어 권고된 체적율과 유사한 수치를 나타내었다. 뇌동맥류의 형태에 구분 없이 체적에 따른 코일 길이는 직경 0.25mm인 한 가지 코일을 사용한 경우 20~$100mm^3$의 $1mm^3$ 당 0.65cm로 조사되었다. saccular type의 aneurysm volume에 사용한 경우 20~$150mm^3$의 $1mm^3$ 당 0.62cm, multi lobulated type의 aneurysm volume에 사용한 경우 20~$90mm^3$의 $1mm^3$ 당 0.60cm로 조사되었다.

• Korean Journal of Radiology
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• 제20권8호
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• pp.1285-1292
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• 2019

Objective: To evaluate the safety and efficacy of the coil-protected technique for liquid embolization in neurovascular malformations. Materials and Methods: Twenty-two patients who underwent coil-protected liquid embolization for symptomatic cranial (n = 13) and spinal (n = 9) arteriovenous fistula (AVF) or arteriovenous malformations (AVMs) were identified. A total of 36 target feeder vessels were embolized with N-butyl cyanoacrylate and/or Onyx (Medtronic). This technique was used to promote delivery of a sufficient amount of liquid embolic agent into the target shunt or nidus in cases where tortuous feeding arteries preclude a microcatheter wedging techniqu and/or to prevent reflux of the liquid embolic agent in cases with a short safety margin. The procedure was considered technically successful if the target lesion was sufficiently filled with liquid embolic agent without unintentional reflux. Angiographic and clinical outcomes were retrospectively evaluated. Results: Technical success was achieved for all 36 target feeders. Post-embolization angiographies revealed complete occlusion in 16 patients and near-complete and partial occlusion in three patients each. There were no treatment-related complications. Of the six patients who showed near-complete or partial occlusion, five received additional treatments: two received stereotactic radiosurgery for cerebral AVM, two underwent surgical removal of cerebral AVM, and one underwent additional embolization by direct puncture for a mandibular AVM. Finally, all patients showed complete (n = 19) or near-complete (n = 3) occlusion of the target AVF or AVM on follow-up angiographies. The presenting neurological symptoms improved completely in 15 patients (68.2%) and partially in seven patients (31.8%). Conclusion: The coil-protected technique is a safe and effective method for liquid embolization, especially in patients with various neurovascular shunts or malformations who could not be successfully treated with conventional techniques.

• Journal of Power Electronics
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• 제17권3호
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• pp.835-847
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• 2017

A transmitting coil with an optimal topology and number of turns can effectively improve the performance of the wireless power transfer (WPT) systems for endoscope robots. This study proposes the evaluation parameters of the transmitting coils related to the performance of the WPT system to standardize the design of the transmitting coils. It considers both the quality factor of transmitting coils and the coupling factor between the two sides. Furthermore, an analytical model of transmitting coils with different topologies is built to exactly estimate the evaluation parameters. Several coils with the specified topologies are wound to verify the analytical model and the feasibility of evaluation parameters. In the case of a constant power received, the related evaluation parameters are proportional to the transfer efficiency of the WPT system. Therefore, the applicable frequency ranges of transmitting coils with different topologies are determined theoretically. Then a transmitting coil with a diameter of 69 cm is re-optimized both theoretically and experimentally. The transfer efficiency of the WPT system is increased from 3.58% to 7.37% with the maximum magnetic field intensity permitted by human tissue. Finally, the standardized design of the transmitting coil is achieved by summing-up and facilitating the optimization of the coils in various situations.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.1064-1069
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• 1994

In order to realize the function of human interface of telecommunications whose objective is to interchange useful information among persons, we developed a bone conduction telephone with which hearing impaired persons with conductive or noise-induced hearing loss and presbycusis can communicate with each other without any other additional devices such as hearing aids. The bone conduction telephone we developed has chatacteristics as follows : (i) a hearing impaired person and a normal hearing person can communicate by bone and air conduction hearings, respectively, using only this telephone set because, as its receiver, it uses a bone conduction vibrator with which we can realize such function with the voice coil and damper of a small speaker unit, the vibrating plate, etc., (ii) it has tone control function compensating hearing losses of hearing impaired persons according to their hearing loss/frequency chatacteristics. Using the tone control function together with a received volume control, it has the received volume range of 20dB in loudness rating; and (iii) it has the function of three emergency calls and a bell lamp as the visual display of a received call.

• 핵의학기술
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• 제18권1호
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• pp.26-32
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• 2014

수술 전 림프절 전이 여부를 진단하고 병리학적 소견 및 원발 주위조직 전이 평가법을 이용하여 두경부암 PET-MRI 검사의 임상적 유용성을 평가하였다. 두경부암 환자 100명을 대상으로 $^{18}F-FDG$ (5.18 MBq/kg)를 정맥주사하고 60분 안정을 취한 후, BiographTM mMR 3T를 사용하여 torso(body tim coil, Vibe-Dixon)와 dedication (head/neck tim coil, UTE, Dotarem injection) 검사를 시행하였다. 반복계산법을 적용하여 데이터를 재구성한 후 workstation으로 림프절 전이 여부를 판독하고, 본원 종합의료정보시스템으로 수술 전/후 병리학적 검사 소견을 조사하였다. 환자의 진단 정보를 $2{\times}2$ 판정행렬의 각 항목에 기입하여 진양성, 진음성, 위양성, 위음성으로 구분하고 이렇게 구분된 검사결과를 토대로 예민도, 특이도, 정확도, 위음성률, 위양성률을 산출하였다. 두경부암 환자의 PET-MRI 검사 결과에서 림프절 전이 양성 및 음성 판정을 받은 경우는 각 49건, 51건이었으며 수술 전-후 병리학적 결과를 통해 림프절 전이 양성 및 음성 판정을 받은 경우는 각 46건, 54건으로 나타났다. 이 중 두 검사 모두 림프절 전이 양성 판정을 받은 진양성은 45건, PET-MRI 검사에서는 림프절 전이 양성이지만 병리학적 검사에서 림프절 전이 음성 판정을 받은 위양성은 4건, PET-MRI 검사에서 림프절 전이 음성이지만 병리학적 검사에서 양성 판정을 받은 위음성은 1건, 두 검사 모두 림프절 전이 음성 판정을 받은 진음성은 50건으로 분석되었다. 따라서 두경부암 환자의 PET-MRI 검사의 예민도는 97.8%, 특이도는 92.5%, 정확도는 95%, 위음성률은 2.1%, 위양성률은 7.0%로 나타났다. 따라서 PET-MRI는 두경부암의 진단에 있어 수술 전 병기 결정이나 치료 후 재발 및 원격전이의 발견, 불분명한 원발 경부 림프절 전이 등의 평가에 유용할 것으로 판단된다.

• Journal of Korean Dental Science
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• 제16권2호
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• pp.182-191
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• 2023

Purpose: This study investigated the orthodontic tooth movement after weekly parathyroid hormone (PTH) injection in mongrel dogs and analyzes bone formation activity on the tension and pressure sides of the tooth movement in mongrel dogs. Materials and Methods: Three mongrel dogs were used in this study. The first premolar was extracted and orthodontic force using 150 g of closed coil springs between the canine and second premolar was applied. The low-dose PTH group (PTH_1) and high-dose PTH group (PTH_2) received weekly injections of 1.61 ㎍/kg and 3.23 ㎍/kg of PTH, respectively. The control group received weekly injections of 1 ml of saline. Clinical, histomorphometric analysis were carried out. Result: The orthodontic tooth movement was greatest in the PTH_2 group and the lowest in the control group. Fluorescence staining images showed higher bone remodeling on the tension side of the tooth movement in the PTH_1 and PTH_2 groups. PTH_2 group showed a thicker labeling band than the PTH_1 group. PTH_2 group showed the highest mineral apposition rate and bone formation rate, followed by the PTH_1 group and the control group. Conclusion: Weekly intermittent PTH injection, especially in the short-term and at higher doses with orthodontic force, successfully increased orthodontic tooth movement and bone remodeling in mongrel dogs.

• Journal of Korean Neurosurgical Society
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• 제65권5호
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• pp.710-718
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• 2022

Objective : Although endovascular treatment for intracranial aneurysms is considered effective and safe, its durability is still debated. Also, few studies have described angiographic follow-up plan after endovascular treatment of intracranial aneurysm, especially in ruptured cases. Hence, we report the long-term results of follow-up angiography protocol. Methods : Radiological records of 639 cases of coil embolization with ruptured aneurysms from March 2003 to December 2016 were retrospectively reviewed. Patients who received treatment of a saccular aneurysm less than 7 mm resulted with near complete occlusion were included. Two hundred thirty-eight aneuryms which received the follow-up angiography at least once were enrolled. We classified four periods of follow-up as follows : post-treatment 1 year (defined as the first period), from 1 to 2 years (the second period), 2 to 5 years (the third period), and over 5 years (long-term). Results : We identified 14 cases (6.4%) of recurrence from 218 aneurysms in follow-up angiography in the first period. Among 143 aneurysms in the second period, five cases (3.5%) of recurrence were identified. There were no findings suspicious of recanalization in 97 patients in the third period. Of the total 238 cases, there were 19 recurrences, for a recurrence rate of 8.0%. Six (31.6%) out of 19 recurrences showed a tendency toward repeat recurrences even after additional treatment. Twenty-eight received long-term follow-up over 5 years and there was no recurrence. Conclusion : Most of the recurrence were found during the first and the second year. We suggest that at least one digital subtraction angiography examination may be necessary around post-treatment 2 years, especially in ruptured cases. If the angiographic results are favorable at 2 years post-treatment, long-term result should be favorable.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.422-427
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• 2008

This study is to illustrate the usefulness of Kriging Dimension Reduction Method(KDRM), which is to construct probability distribution of response function in the presence of the physical uncertainty of input variables. DRM has recently received increased attention due to its sensitivity-free nature and efficiency that considerable accuracy is obtained with only a few number of analyses. However, the DRM has a number of drawbacks such as instability and inaccuracy for functions with increased nonlinearity. As a remedy, Kriging interpolation technique is incorporated which is known as more accurate for nonlinear functions. The KDRM is applied and compared with MCS methods in a compression coil spring design problem. The effectiveness and accuracy of this method is verified.

• 한국소음진동공학회논문집
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• 제13권11호
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• pp.875-881
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• 2003

The received signal of a mobile phone is normally sensed through two independent means which are the sound generation of a speaker and vibration generation of a vibration motor. As an improvement scheme to meet the consumer's demand on weight reduction and miniaturization of a mobile phone, the design and development of an integrated vibration and sound generating device are performed in this research. To this purpose, the optimal shapes of the voice coil. the permanent magnet and the vibration plate are designed, and the excitation force applied to the vibration system of the new device is estimated and verified through theoretical analyses, computer simulation, and experiments using an expanded model. In addition, vibration performance comparison of the device with the existing vibration motor is performed, and from the overall process, therefore, the method and procedure for the vibration performance analysis of the integrated vibration and sound generating device are established.