• 대한청각학회지
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• 제24권1호
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• pp.17-23
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• 2020

Background and Objectives: We aimed to measure the head dimensions on computed tomography (CT) images, to compare them to directly measured head dimensions, and to predict a new parameter of bone thickness for aiding bone conduction implant (BCI) placement. Subjects and Methods: We reviewed the facial and mandibular bone CT images of 406 patients. Their head sizes were analyzed using five parameters included in the 6th Size Korea project, and they were divided into age groups (ranging from the 10s to the 80s). We compared the head length, head width, sagittal arc, bitragion arc, and head circumference in the CT and Size Korea groups. We also added the parameter bone thickness for aiding BCI placement. Results: All the head size parameters measured using CT were significantly smaller than those measured directly, with head length showing the smallest difference at 7.85 mm. The differences in the other four parameters between the two groups according to patient age were not statistically significantly different. Bone thickness had the highest value of 4.89±0.93 mm in the 70s and the lowest value of 4.10±0.99 mm in the 10s. Bone thickness also significantly correlated with head width (p=0.038). Conclusions: Our findings suggested that the CT and direct measurements yielded consistent data. Moreover, CT enabled the measurement of bone sizes, including bone thickness, that are impossible to measure directly. CT measurements may complement direct measurements in the Size Korea data when used for developing bone conduction hearing devices (BCIs and headsets) for the Korean population.

• 한국농공학회지
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• 제34권1호
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• pp.41-48
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• 1992

Various soil behaviors usually occurring in the geotechnical problems, such as, cutting and embankments, stability of slope, seepage, consolidations, shearing failures and liquefaction, should be predicted and analyzed in any way. An approach of these predictions may be followed by the development of the constitutive equations as first and subsequently solved by numerical methods. The purpose of this paper is develop the constitutive equation of sands uder monotonic or cyclic loadings. The constitutive equation which is based on elasto-plastic theory, modified anisotropic consolidated stress parameter by Sekiguchi et al and Pender's theory is derived. And the equation is included a new stress parameter, hardening function, Bauschinger's effects and Pender's theory. The model is later evaluated and confirmed the validity by the test data of Ottawa sand, Banwol sand Hongseong sand. The following conclustions may be drawn: 1. The consititutive equation which is based on elasto-plastic theory, modified anisotropic consolidated stress parpameter by Sekiguchi et al and Pender's theory is derived. The equation in included a new stress parameter, hardening function, Bauschinger's effect and Pender's theory. 2. For Ottawa sand, the result of the constitutive equation shows a better agreement than that of Oka et al. The result of axial strain agrees well with the tested data. However, the result of horizontal strain is little bit off for the cyclic loadings or large stress. It is thought that the deviation may be improved by considering Poisson's ratio and precise measurement of shear modulus. 3. Banwol sand is used for the strain and stress tests with different relative densitites and confining pressures. The predeicted result shows a good agreement with the tested data because the required material parameters were directly measurd and determined form this laboratory. 4. For Hongseong sand, the tests under same amplitude of cyclic deviatoric stress shows a similar result with the tested data in absolute strain. It shows the acute shape of turning point because the sine wave of input is used in the test but the serrated wave in prediction.

• 전자공학회논문지
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• 제50권9호
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• pp.55-59
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• 2013

Sub-$0.1{\mu}m$로 스케일이 감소함에 따라 기생 저항 효과가 크게 발생되는 dc Ids 측정 데이터 없이 측정 S-파라미터로부터 얻어진 RF Ids를 사용하여 벌크 MOSFET의 포화영역에서 게이트 전압 종속 유효 캐리어 속도를 추출하는 새로운 방법이 개발되었다. 이 방법은 바이어스 종속 기생 게이트-소스 캐패시턴스와 유효 채널 길이의 복잡한 추출 없이 포화영역의 유효 캐리어 속도를 추출할 수 있게 한다. 이러한 RF 기술을 사용하여 벌크 포화 속도를 초과하는 전자 속도 overshoot 현상이 $0.065{\mu}m$ 게이트 길이의 벌크 N-MOSFET에서 관찰되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.413-416
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• 1998

Sensitivity and calibration considerations are most important in the design and implementation of real control systems. Ideally parameter changes due to various causes should not appreciably affect the system's performances. But all the values of physical components of the plants and controllers as well as the relevant environmental conditions change in time, thus the output performance can be deteriorated during the operating span of the system. Naturally the duty of calibration or the prevention of performance deterioration due to excessive component sensitivity should be provided to the control system. In this paper, we propose a digital controller which has the capability of calibration and gain adjustment as well as the execution of control law. Specifically the problems of gain adjustment and offset calibration in the light source and CdS sensor module for position measurement in a flexible link system are considerably resolved. The parameters of measurement module are prone to change due to environmental brightness conditions resulting in poor steady state performance of the overall control system. Thus a proper method is necessary to provide correction to the changed values of gain and offset in the position measurement module. The proposed controller, whenever necessary, measures the open-loop characteristics, andthen calculates the offset and sensor gain correction values based on the prepared standard measurements. It is applied to the control of a flexible link system with the gain and offset calibration porblems in the light sensor module for position to show the applicability.

• Smart Structures and Systems
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• 제19권6호
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• pp.679-694
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• 2017

The complexity, enlargement and irregularity of structures and multi-directional dynamic loads acting on the structures can lead to unexpected structural behavior, such as torsion. Continuous torsion of the structure causes unexpected changes in the structure's stress distribution, reduces the performance of the structural members, and shortens the structure's lifespan. Therefore, a method of monitoring the torsional behavior is required to ensure structural safety. Structural torsion typically occurs accompanied by displacement, but no model has yet been developed to measure this type of structural response. This research proposes a model for measuring dynamic torsional response of structure accompanied by displacement and for identifying the torsional modal parameter using vision-based displacement measurement equipment, a motion capture system (MCS). In the present model, dynamic torsional responses including pure rotation and translation displacements are measured and used to calculate the torsional angle and displacements. To apply the proposed model, vibration tests for a shear-type structure were performed. The torsional responses were obtained from measured dynamic displacements. The torsional angle and displacements obtained by the proposed model using MCS were compared with the torsional response measured using laser displacement sensors (LDSs), which have been widely used for displacement measurement. In addition, torsional modal parameters were obtained using the dynamic torsional angle and displacements obtained from the tests.

• 한국초전도ㆍ저온공학회논문지
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• 제7권1호
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• pp.47-50
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• 2005

The AC loss is an important issue in the design of the high temperature superconductor (HTS) power cables, which consist of a number of lli 2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. These make loss measurements considerably complex, especially for short samples of laboratory size. In this work we have prepared a multi-tape conductor composed of Bi-2223 tapes. The at losses of the conductor have experimentally investigated. The loss tests indicate that the effect of tapes critical currents on AC loss measurement in the multi tape conductor is negligible only if currents in the tapes flow uniformly Moreover, the measured tosses of the conductor are in good agreement with the sum of the transport losses in the tapes. However, in the case of non-uniform current distributions, the measured AC losses considerably depend on the current distribution parameter of the positioning of a voltage lead. Thus special cautions should be needed for the measurement of the true AC losses in the short power cable samples.

• 한국전자파학회논문지
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• 제24권5호
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• pp.541-548
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• 2013

본 논문에서는 상용 벡터 회로망 분석기를 사용하지 않고도, 신호 발생기, 벡터 전압 수신기, 방향성 결합기, 주파수 혼합기 등의 기본적인 초고주파 장비/소자를 활용하여 평가하고자 하는 초고주자 소자의 2-포트 산란 계수를 측정할 수 있는 시스템을 제안한다. 벡터 회로망 분석기를 대용할 수 있는 산란 계수 측정 시스템의 해석적 모델과 제작방법을 제시하고, 이를 1-포트와 2-포트 소자에 대하여 각각 적용한 산란 계수를 측정하여 구현된 시스템을 평가하였다. 평가 주파수 대역에 따라 비교적 낮은 대역에서는 단일 신호 발생기와 벡터 전압 수신기를 사용한 직접 수신법을, 높은 대역에서는 추가의 신호원과 주파수 혼합기를 사용하여 신호를 하향 복조하는 헤테로다인 방식을 사용하여 산란 계수를 결정짓는 벡터 전압을 수신하였다. 이들 각각의 수신 방법으로 UHF와 X 대역 초고주파 소자의 2-포트 산란 계수를 평가하였고, 그 유효성을 상용 벡터 회로망 분석기로 검증하였다.

• 마이크로전자및패키징학회지
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• 제17권3호
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• pp.43-49
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• 2010

직접인쇄기술 방식은 기존의 포토리소그래피 방법을 이용한 패터닝 기술에 비해 저비용, 간단한 공정 과정, 친환경성 등 여러 장점들로 인해 미세 회로 형성 분야의 그린 테크놀로지로 최근 각광받고 있다. 이러한 프린팅 기반의 전자기술을 상용화하기 위해서는 프린팅 방식으로 형성된 회로의 전기적 특성 평가가 필수적인데, 이에 본 연구에서는 구리 잉크를 이용하여 잉크젯 프린팅 방식으로 2 가지 타입, parallel transmission line(PTL)과 coplanar waveguide(CPW) 구조의 회로를 형성하고 $250^{\circ}C$에서 30분 동안 소결하여 완성하였다. 전류-전압 그래프로 직류 저항을 측정하여 벌크 구리의 비저항 값의 약 3.3배되는 평균 0.558 ${\mu}{\Omega}{\cdot}cm$의 비저항 값을 도출하였고 회로의 고주파 특성 평가를 위해 주파수 범위 0~30 GHz에서 probe station chuck과 샘플 간의 갭 유무에 따른 scattering parameter를 측정하였다. 모든 시편에서 5 dB 이하의 반사 특성을 보였으며, PTL 회로가 CPW 구조보다 전반적으로 더 좋은 통과 특성을 나타내었다.

• 대한의용생체공학회:의공학회지
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• 제21권2호
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• pp.219-224
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• 2000

본 연구는 몸통의 반복적인 flexion/extension 동작 수행시 근전도신호를 측정하고 이들 신호에서 나타난 EMG parameters(median frequency, median power, RMS) 와 피실험자의 주관적 불편도의 변화양상간의 정량적인 관계를 알아보고자 수행되었다. 피실험자별로 3-5회 정해진 업무를 수행하였고 주관적불편도와 근전도 신호를 측정하였다. 실험결과 반복횟수가 증가할수록 주관적 불편도는 증가하였으며 각 task 별로 EMG parameter와 불편도의 증감율 간의 회귀분석과 상관분석을 수행한 결과 실험과 EMG parameter에 따른 변이는 존재했지만 대체로 RMS에 비해 MF와 MP의 증감율이 불편도 증감율과 상관관계가 높은 것으로 나타났다.

• 대한전기학회논문지
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• 제37권5호
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• pp.311-318
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• 1988

An adaptive control problem for a plant with unmodelled dynamics is studied. The upper bounds of the output due to the unmodelled dynamics and measurement noise is assumed to be known. This problem was studied by Middleton et al. They used a modified form of the least square method in estimating the plant paramaters. In this paper, the bounds of the parameters are estimated by linear programming and the parameters are estimated by the projetion type algorithm incorporating the bounds of the parameters. The stability of the proposed adaptive control system can be proved in nearly the same way as the proof of Middleton. The performance of the proposed method is found to be much better than the method of Midlleton's with respect to the parameter convergence and plant output in computer simulations.