• Journal of Korean Neurosurgical Society
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• v.61 no.2
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• pp.258-266
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• 2018

Objective : The diagnosis of insufficiency fractures of the sacrum in an elder population increases annually. Fractures show very different morphology. We aimed to classify sacral insufficiency fractures according to the position of cortical break and possible need for intervention. Methods : Between January 1, 2008 and December 31, 2014, all patients with a proven fracture of the sacrum following a low-energy or an even unnoticed trauma were prospectively registered : 117 females and 13 males. All patients had a computer tomography of the pelvic ring, two patients had a magnetic resonance imaging additionally : localization and involvement of the fracture lines into the sacroiliac joint, neural foramina or the spinal canal were identified. Results : Patients were aged between 46 and 98 years (mean, 79.8 years). Seventy-seven patients had an unilateral fracture of the sacral ala, 41 bilateral ala fractures and 12 patients showed a fracture of the sacral corpus : a total of 171 fractures were analyzed. The first group A included fractures of the sacral ala which were assessed to have no or less mechanical importance (n=53) : fractures with no cortical disruption ("bone bruise") (A1; n=2), cortical deformation of the anterior cortical bone (A2; n=4), and fracture of the anterolateral rim of ala (A3; n=47). Complete fractures of the sacral ala (B; n=106) : parallel to the sacroiliac joint (B1; n=63), into the sacroiliac joint (B2; n=19), and involvement of the sacral foramina respectively the spinal canal (B3; n=24). Central fractures involving the sacral corpus (C; n=12) : fracture limited to the corpus or finishing into one ala (C1; n=3), unidirectional including the neural foramina or the spinal canal or both (C2; n=2), and horizontal fractures of the corpus with bilateral sagittal completion (C3; n=8). Sixty-eight fractures proceeded into the sacroiliac joint, 34 fractures showed an injury of foramina or canal. Conclusion : The new classification allowes the differentiation of fractures of less mechanical importance and a risk assessment for possible polymethyl methacrylate leaks during sacroplasty in the direction of the neurological structures. In addition, identification of instable fractures in need for laminectomy and surgical stabilization is possible.

• Fashion & Textile Research Journal
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• v.20 no.5
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• pp.616-620
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• 2018

Recently, many researches have been conducted to improve the performance and wearability of smart wearables. In this study, we designed and fabricated the signal and power transmission textile cables for smart wearables which have excellent wearability, durability and reliability. For the signal transmission textile cables, conductive yarns for the signal line and the ground line were developed. Three types of signal transmission textile cables have been developed using the conductive yarns. Linear density, tensile properties, electrical resistance and RF characteristics were tested to characterize the physical and electrical properties of three signal transmission textile cables. The conductive yarns have the very low resistance of $0.05{\Omega}/cm$ and showed excellent uniformity of electric resistance. Therefore, the electrical resistance of the signal transmission fiber cable can be reduced by increasing the number of conductive yarns used in signal and ground lines. However, the radio frequency (RF) characteristics of the signal transmission textile cables were better as the number of strands of the conductive yarns used was smaller. This is because the smaller the number of strands of conductive yarn used in signal transmission textile cables, the narrower and more parallel the distance between the signal line and the ground line. It is expected that the signal and power transmission textile cable for signal and power transmission will be utilized in smart wearable products.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.15-19
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• 2001

This paper presents an modelling and analysis of SSSC and UPFC in static analysis of power systems. SSSC is used to control active power flow in transmission lines by controlling the phase angle of the injected voltage source which is in rectangular to the line current. UPEC is used to control the magnitude and phase of the injected voltage sources which are connected both in series and in parallel with the transmission line to control power flow and bus voltage. To compare the effect of SSSC and UPFC in power system static analysis, the PSS/E simulation program is used. As the FACTS device model such as SSSC and UPFC is not provided in PSS/E yet, an equivalent load model is used. This procedure is implemented by IPLAN which is an external macro program of PSS/E. The simulation results show that UPFC is more effective to improve bus voltage than SSSC in power system static analysis.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.7
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• pp.10-16
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• 1999

This paper describes a low voltage swing bus driver using FCSR(Feedback Control Swing voltage Reduction) which can control bus swing voltage within a few hundred of mV. It is proposed to reduce power consumption in On-chip interface, especially for MDL(Merged DRAM Logic) architecture wihich has wide and large capacitance bus. FCSR operates on differential signal dual-line bus and on precharged bus with block controlling fuction. We modeled driver and bus to scale driver size automatically when bus environment is variant. We also modeled coupling capacitance noise(crosstalk) of neighborhood lines which operate on odd mode with parallel current source to analysis crosstalk effect in the victim-line according as voltage transition in the aggressor-line and environment in the victim-line. We built a test chip which was designed to swing 600mV in bus, shows 70Mhz operation at 3.3V, using Hyundai 0.8um CMOS technology. FCSR operate with 250Mhz at 3.3V by Hspice simulation.

• The Mathematical Education
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• v.37 no.1
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• pp.1-13
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• 1998

In this paper, we have represented the efficient way how to enumerate the optimal number-right scores to adjust the item difficulty and to improve item discrimination. To estimate the optimal number-right scores in two equivalent math-tests by linear score equating a measurement error model was applied to the true scores observed from a pair of equivalent math-tests assumed to measure same trait. The model specification for true scores which is represented by the bivariate model is a simple regression model to inference the optimal number-right scores and we assume again that the two simple regression lines of raw scores and true scores are independent each other in their error models. We enumerated the difference between mean value of $\chi$＊ and ${\mu}$$\_$$\chi$/ and the difference between the mean value of y＊and a＋b${\mu}$$\_$$\chi$/ by making an inference the estimates from 2 error variable regression model. Furthermore, so as to distinguish from the original score points, the estimated number-right scores y’$\^$*/ as the estimated regression values of true scores with the same coordinate were moved to center points that were composed of such difference values with result of such parallel score moving procedure as above mentioned. We got the asymptotically normal distribution in Figure 5 that was represented as the optimal distribution of the optimal number-right scores so that we could decide the optimal proportion of number-right score in each item. Also by assumption that equivalence of two tests is closely connected to unidimensionality of a student’s ability. we introduce new definition of trait score to evaluate such ability in each item. In this study there are much limitations in getting the real true scores and in analyzing data of the bivariate error model. However, even with these limitations we believe that this study indicates that the estimation of optimal number right scores by using this enumeration procedure could be easily achieved.

• Journal of Korean Foot and Ankle Society
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• v.9 no.2
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• pp.188-192
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• 2005

Purpose: It is to analyze the clinical utility of radiograhpic measurements for the insertional Achilles tendinitis patients who have Haglund's deformity and to evaluate the radiographic values related to Haglund's deformity in normal Korean population. Materials and Methods: We used the angle of Fowler and Philip, parallel pitch lines (PPL) and Chauveaux-Liet (CL) angle as radiographic measurements. We examined 50 cases of insertional Achilles tendinits patients and another 50 cases of normal foot as a control. Results: In normal feet, the mean value of angle of Fowler and Philip was $53.22^{\circ}$, CL angle was $-33.14^{\circ}$ and the PPL showed positive in 48%. In case of insertional Achilles tendinitis, the mean values were $55.39^{\circ}$, $-33.63^{\circ}$, positive in 56% respectively. There were not statistically significant differences (p>0.05). Conclusion: The radiographic values for Haglund's deformity between insertional Achilles tendinitis feet and the normal feet did not show significant difference. Therefore, it seems that the clinical utility of radiographic measurements for the insertional Achilles tendinitis with Haglund's deformity is not useful and the development of new diagnostic methods as MRI and ultrasonography is required.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1108-1115
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• 2004

A new type of a Rotman lens is presented in this paper fur millimeter-wave applications, such as collision avoidance radar. A dielectric slab Rotman lens is proposed to reduce the conductor loss and to create an appropriate farm for favorable implementation at millimeter-wave frequency. The proposed lens consists of a dielectric slab and slot lines whereas the conventional lenses are constructed with parallel conducting plates. The dielectric slab Rotman lens excited in TE$\_$0/ mode shows a high degree of confinement for the fields, low dispersion, and has an appropriate feed structure. A prototype lens has been designed and fabricated with 9 beam ports and 9 array ports together with 9 tapered slot antennas. This lens has been tested in the range from 10 GHz to 15 GHz and the measured beam widths are about 15$^{\circ}$ at 13 GHz. The measurements also show low mutual coupling between beam ports and an efficiency of about 34.6 %. The overall performance is comparable to that of conventional Rotman lenses even though the prototype was tested at lower than desired frequencies in the microwave frequency range due to our limited resources for fabrications and measurements. It is expected that at millimeter-wave frequency the dielectric slab Rotman lens will have lower conductor loss and lower mutual coupling than conventional Rotman lenses.an lenses.

• Journal of Sensor Science and Technology
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• v.9 no.2
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• pp.120-126
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• 2000

This paper dealt with the developed portable electric field meter which consisted of planar-type sensor, analog amplifier with gain controller, A/D convertor, and display unit. The principle of the planar-type sensor for detecting time-varying electric field of extremely low frequency (ELF) bandwidth was described, and a calibration system using cylindrical guard electrodes and parallel-plate electrodes was proposed. From the calibration experiment, the frequency bandwidth and the sensitivity of the developed electric field meter was $17[Hz]{\sim}7[kHz]$, and 4.45[mV/V/m], respectively. Also it can measure the electric field strength up to 10[kV/m], and the measured result was displayed on the liquid crystal display in digit. The electric field meter can be widely applied to measure electric field strength radiated from power lines, computers, and home appliances such as hair dryer, heater, etc.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.11
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• pp.1429-1436
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• 1999

데이타들에 대한 선인출 효과를 얻기 위하여 캐쉬 메모리의 캐쉬 블록은 다중 워드로 구성된다. 그러나 선인출된 데이타들이 사용되지 않을 경우 캐쉬 메모리가 낭비되고 따라서 캐쉬 실패율이 증가한다. 데이타 배열 병합 방법은 캐쉬 실패 원인의 하나인 캐쉬 충돌 실패를 감소시키기 위하여 사용되고 있다. 그러나 기존의 배열 병합 방법은 유용하지 못한 데이타들을 캐쉬 블록에 선인출하는 현상을 보인다. 본 논문에서는 이러한 현상을 개선한 스트라이드 배열 병합을 제안한다. 모의시험에서 캐쉬 블록이 다중 워드로 구성된 경우 스트라이드 배열 병합은 캐쉬 충돌 실패를 감소시킬 뿐 만 아니라 유용한 데이타 선인출을 증가 시키므로 캐쉬 성능을 향상시킴을 보여준다. 또한 이렇게 향상된 캐쉬 성능은 프로세서 증가에 따른 확장성 있는 프로그램 성능을 나타낸다.Abstract The cache memory is composed of cache lines with multiple words to achieve the effect of data prefetching. However, if the prefetched data are not used, the spaces of the cache memory are wasted and thus the cache miss rate increases. The data merging-arrays method is used for the sake of the reduction of the cache conflict misses. However, the existing merging-arrays method results in the useless data prefetching. In this paper, a stride merging-arrays method is suggested for improving this phenomenon. Simulation results show that when a cache line is composed of multiple words, the stride merging-arrays method increases the cache performance due to not only the reduction of cache conflict misses but also the useful data prefetching. This enhanced cache performance also represents the more scalable performance of parallel applications according to increasing the number of processors.

• Journal of the Korean earth science society
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• v.31 no.7
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• pp.708-719
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• 2010

The Gochang-gun Dongho macro-tide pocket-type beach, located on the southwestern coast of Korea, is investigated in terms of the seasonal variations of surface sediment and sedimentary environment. Surface sediments of 45 sites in four seasons (May 2006-February 2007) are sampled across three survey lines (15 sites in each survey line). The surface sediments of the Dongho Beach are mainly composed of fine to coarse sands, and the ratio of fine sand is the largest. The average of grain size is the coarsest in the summer. The spatial distribution of surface sediments shows a coast-parallel band of fine and medium sands during three seasons of spring, fall, and winter, whereas medium sands dominated in the northern part of the study area during the summer. These results suggest that a tide is more effective than a wave in the surface sediments of the Dongho Beach during the summer.