• Journal of Korean Neurosurgical Society
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• v.43 no.2
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• pp.79-84
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• 2008

Objective: The length of anterior-posterior commissure (AC-PC) in racial groups, age, gender of patients with deep brain stimulation (DBS) and pallidotomy were investigated. Methods: From January 1996 to December 2003, 211 patients were treated with DBS and pallidotomy. There were 160 (76%) Caucasians, 35 (17%) Hispanics, 12 (5%) Asians and 4 Blacks (2%). There were 88 males and 52 females in DBS-surgery group and 44 males, 27 females in pallidotomy group. Mean age was 58 year-old. There were 19 males and 19 females and mean age was 54.7 years in the control group. Measurements were made on MRI and @Target software. Results: The average AC-PC distance was 24.89 mm (range 32 to 19), which increased with aging until 75 years old in Caucasian and also increased with aging in Hispanic, but the AC-PC distance peaked at 45 years old in Hispanic. The order of AC-PC distance were $24.6{\pm}2$ mm in Caucasian, $24.6{\pm}2.24$ mm in Asian, 24.53 mm in Black, $23.6{\pm}1.98$ mm in Hispanic. The average AC-PC distance in all groups was 24.22 mm in female who was mean age of 56.35, 25.28 mm in male who was mean age of 60.19 and $24.5{\pm}2$ mm in control group that was excluded because of the difference of thickness of slice. According to multiple regression analysis, the AC-PC distance was significantly correlated with age, race, and gender. Conclusion: The AC-PC distance is significantly correlated with age, gender, and race. The atlas of functional stereotaxis would be depended on the Variation of indivisual brain that can influenced by aging, gender, and race.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.210-210
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• 2007

RF circuit을 구현하는데 있어서 기판의 전기적 특성을 정확하게 아는 것은 매우 중요하다. 왜냐하면 초고주파로 갈수록 기판의 전기적인 특성이 circuit에 많은 영향을 미치고 이러한 영향을 고려한 circuit를 설계해야 원하는 결과를 얻을 수 있기 때문이다. 본 연구에서는 현재 사용되고 있는 PI 기판의 전기적인 특성인 유효 유전율과 loss tangent 값을 캐패시터를 이용해 정확하게 측정하고자 했다. 캐패시터의 conductor material은 Cu를 사용하였고 PI 기판의 투께는 25um 를 이용하였다. PI 기판의 유효 유전율은 캐패시터 측정에 의한 data률 EM simulation tool 을 통해 분석한 후 간단한 수식에 의해 구했다. 또한 PI 기판의 loss tangent 값을 구하기 위해 캐패시터의 dissipation factor를 분석하였다. 캐패시터의 dissipation factor는 dielectric loss, AC 저항에 의한 loss, DC 저항에 의한 loss를 포함한다, DC 저항에 의한 loss는 dissipation factor에 차지하는 비율이 낮기 때문에 생략이 가능하다. 하지만 AC 저항에 의한 loss는 주파수에 비례하여 값이 커지게 된다. 따라서 주파수가 올라 갈수록 dissipation factor도 상승하게 되는데 주파수의 전 대역에서 AC 저항에 의한 loss를 보정해주면 dielectric loss를 얻을 수 있다. 추출된 dielectric loss를 통해 PI 기판의 loss tangent 값을 구하였다. 캐패시터를 이용한 PI 기판의 전기적 특성 추출은 간단한 구조를 통해 얻을 수 있기 때문에 다른 재료의 기판의 전기적 특성을 추출하는데도 이용이 용이하다.

• Clinics in Shoulder and Elbow
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• v.26 no.2
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• pp.140-147
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• 2023

Background: The management of acromioclavicular (AC) joint dislocation remains controversial. Recently, anatomic coracoclavicular (CC) fixation with a double clavicular tunnel and three flip-buttons has shown promising results. This study aimed to evaluate functional and radiological outcomes in patients with high-grade AC joint dislocation treated with anatomic CC fixation using double clavicular tunnels and three flip-buttons. Methods: A retrospective, unicentric study was performed. The study included patients with high-grade AC joint dislocation who underwent surgery with anatomic CC fixation using double clavicular tunnels and three flip-buttons. Demographic data were obtained from medical records. A functional evaluation using subjective shoulder value (SSV), visual analog scale (VAS), and disabilities of the arm, shoulder, and hand (DASH) questionnaires was performed, and an evaluation of preoperative and postoperative comparative Zanca view images was performed. Factors associated with functional outcomes and radiological AC reduction were analyzed. Results: A total of 83 patients completed follow-up and were included in the analysis. The mean SSV, VAS, and DASH scores were 92.8, 0.8, and 6.4, respectively. Patients who had complications experienced significantly worse functional outcomes (DASH: P=0.037). Suboptimal final AC reduction was observed in nine patients (11.1%), and significantly more frequently in patients older than 40 years (P=0.031) and in surgeries performed more than 7 days after injury (P=0.034). There were two reoperations (2.4%). Conclusions: Anatomic CC fixation with a double clavicular tunnel and three flip-buttons leads to good functional outcomes, low complication rates, and high rates of optimal AC reduction.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.296_297
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• 2009

다층구조의conductor와 shield로 구성되는 HTS-cable의 교류손실 특성 연구를 위하여 2005년부터 실증시험 중에 있는 22.9kV, 50MVA, 100m급 KEPCO HTS-cable system에 사용된 케이블과 동일한 두개의 short-sample에 대하여DC 및 AC 특성을 실험적으로 조사하였다. KEPCO HTS-cable system에서처럼 shield전류를 conductor와 크기는 같게 하고 방향을 반대로하여 수주기동안 AC pulse전류를 인가했을 때, shield의 임계전류가 conductor보다 작음에도 불구하고 conductor-lead에 대하여 측정된 AC loss가 shield의 것과 비교하여 약 1.5배 큰 것을 알 수 있었다

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.8
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• pp.420-424
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• 2004

This paper presents experimental data from model windings with different arrangement of coil in order to provide information to design a 22.9kV class HTS transformer. Before experiment, the composite insulation of two different type of HTS transformers are investigated. The first basic of investigation is a breakdown characteristic of liquid nitrogen and flashover characteristic on the GFRP surface under ac and impulse, The second investigation is insulation design, manufacture and test of model windings. These include a AC withstand voltage test of 50 kV rms and a lighting impulse test of 150 kV at peak.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.750-752
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• 2002

An HTS power cable has multi-layer conductor structure to increase the current capacity. However, usually the current is not evenly distributed among the layers. This paper describes a method to make the current distribution more uniform and hence reduce the AC loss. Also. this paper shows recommendation for future cable conductor prototypes.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.579-582
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• 1989

The air-cooled waterwheel generator has a fan connected to waterwheel shaft or motor driven fan or fans. The fans are operated at constant speed, constant input, regardless of generator loss which is varied according to generator output and coolant the perature. Energy savings may he possible if the cooling air flow is controlled according to generato output and air temperature depending on season. The simulation and experience have been done on the 22.6 KVA Waterwheel generator by using AC variable speed drive. The results gave us los cut of generator.

• Journal of Korean Neurosurgical Society
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• v.38 no.5
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• pp.359-365
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• 2005

Objective : The study investigates the extent of brain shift and its effect on the accuracy of the stereotaxic procedure. Methods : Thirty-five patients underwent 40stereotactic procedures between June 2002 and March 2004. There were 26 males, mean age 59years old. There were 34procedures for Parkinson's disease, 2 for essential tremor, 3 for cerebral palsy, 1 for dystonia. Patients were divided in four groups based on postoperative pneumocephalus : under 5cc [9 procedures], between $5{\sim}10cc$ [13procedures], between $10{\sim}15cc$ [11 procedures] and more than 15cc [7procedures]. The coordinates of the anterior commissure[AC], posterior commissure[PC], and target were defined in pre-and intraoperative magnetic resonance image scans and the amount of air volume was measured with @Target (BrainLab, Heimstetten, Germany]. Results : The mean AC-PC was 26.5mm for patients with less than 5cc, 26.9mm for $5{\sim}10cc$, 25.8mm for $10{\sim}15cc$ and 26.2mm for more than 15cc. The length of AC-PC line and coordinates of AC, PC was also not statistically different, Euclidean distance as well as ${\Delta}x$, ${\Delta}y$, ${\Delta}z$ of AC, PC, and target were also not statistically different among the groups [p>,1]. There was a variance in target of $0.7{\sim}7.6mm$, Euclidean distance of 2.5mm, related to electrophysiology but not to brain-shift. Conclusion : The amount of air accumulated in the intracranial space and compressing the cortical surface has no effect on the localization of subcortical stereotactic target and landmarks.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.68-73
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• 2015

Purpose The purpose of this study was to evaluate image quality change by truncated region in field of view (FOV) of attenuation correction computed tomography (AC-CT) in brain PET/CT. Materials and Methods Biograph Truepoint 40 with TrueV (Siemens) was used as a scanner. $^{68}Ge$ phantom scan was performed with and without applying brain holder using brain PET/CT protocol. PET attenuation correction factor (ACF) was evaluated according to existence of pallet in FOV of AC-CT. FBP, OSEM-3D and PSF methods were applied for PET reconstruction. Parameters of iteration 4, subsets 21 and gaussian 2 mm filter were applied for iterative reconstruction methods. Window level 2900, width 6000 and level 4, 200, width 1000 were set for visual evaluation of PET AC images. Vertical profiles of 5 slices and 20 slices summation images applied gaussian 5 mm filter were produced for evaluating integral uniformity. Results Patient pallet was not covered in FOV of AC-CT when without applying brain holder because of small size of FOV. It resulted in defect of ACF sinogram by truncated region in ACF evaluation. When without applying brain holder, defect was appeared in lower part of transverse image on condition of window level 4200, width 1000 in PET AC image evaluation. With and without applying brain holder, integral uniformities of 5 slices and 20 slices summation images were 7.2%, 6.7% and 11.7%, 6.7%. Conclusion Truncated region by small FOV results in count defect in occipital lobe of brain in clinical or research studies. It is necessary to understand effect of truncated region and apply appropriate accessory for brain PET/CT.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.6
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• pp.91-98
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• 2004

This paper proposes a PCB plane model for generic SPICE circuit simulators. The proposed model reflects two frequency-dependent losses, namely skin and dielectric losses. After power/ground plane pair is divided into arrays of unit-cells, each unit-cell is modeled using a transmission line and two loss models. The loss model is composed of a resistor for DC loss, series HL ladder circuit for skin loss and series RC ladder circuit for dielectric loss. To verify the validity of the proposed model, it is compared with SPICE ac analysis using frequency-dependent resistors. Also, we show that the estimation results using the proposed model have a good correlation with that of VNA measurement for the typical PCB stack-up structure of general desktop PCs. With the proposed model, not only ac analysis but also transient analysis can be easily done for circuits including various non-linear/linear devices since the model consists of passive elements onl.