• Steel and Composite Structures
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• 제38권4호
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• pp.355-363
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• 2021

The present paper attempts to investigate the propagation of plane waves in an isotropic elastic medium under the effect of initial stress and temperature-dependent properties. The modulus of elasticity is taken as a linear function of the reference temperature. The formulation is applied under the thermoelasticity theory with dual-phase-lag; the normal mode analysis is used to obtain the expressions for the displacement components, the temperature, the stress, and the strain components. Numerical results for the field quantities are given in the physical domain and illustrated graphically. Comparisons are made with the results predicted by different theories (Lord-Shulman theory, the classical coupled theory of thermoelasticity and the dual-phase-lag model) in the absence and presence of the initial stress as well as the case where the modulus of elasticity is independent of temperature.

• 한국정밀공학회지
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• 제12권9호
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• pp.167-174
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• 1995

This paper experimentally demonstrates the feasibility of using shape memory alloy(SMA) actuators in controlling structural vibrations of a flexible cantilevered beam. The dynamic characteristics of the SMA actuator are identified and integrated with the beam dynamics. Three types of control schemes; constant amplitude controller(CAC), proportional amplitude controller (PAC) and sliding mode controller(SMC) are designed. The CAC and PAC are determined on the basis of physical phenomenon of the SMA actuator, while teh SMC is formulated in a mathematical manner. The proposed controllers are implemented and evaluated at various operating condirions by investigating the control level of suppression in transient vibration.

• 한국분무공학회지
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• 제27권1호
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• pp.26-35
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• 2022

Electrospray is a method of atomizing fluid using high voltage supply and capable of generating continuous flow and coherent size of droplets. Electrical system and properties of fluids has enabled electrospray to have various spray modes. However, its studies have been confined only in Cone jet, which is more stable and easier to manipulate droplets' size than other spraying modes. Therefore, it is necessary to investigate and compare other spraying modes based on experimental parameters and physical properties of fluids. This research paper identified nine different spray modes. It was found out that Sauter Mean Diameter (SMD) is proportional to flow rate of fluids and maximum difference among spray modes was 1.7 times. On the other hand, SMD standard deviation had low variations on specific flow rates of fluids. Pulsed jet mode recorded the largest SMD standard deviation, while Spindle recorded the lowest.

• Geomechanics and Engineering
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• 제37권3호
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• pp.243-251
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• 2024

In the current work, a poro-thermoelastic half-space issue with temperature-dependent characteristics and an inclined load is examined in the framework of the three-phase-lag model (3PHL) while taking into account the effects of magnetic and gravity fields. The resulting coupled governing equations are non-dimensional and are solved by normal mode analysis. To investigate the impacts of the gravitational field, magnetic field, inclined load, and an empirical material constant, numerical findings are graphically displayed. MATLAB software is used for numerical calculations. Graphs are used to visualize and analyze the computational findings. It is found that the physical quantities are affected by the magnetic field, gravity field, the nonlocal parameter, the inclined load, and the empirical material constant.

• Physical Therapy Rehabilitation Science
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• 제9권2호
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• pp.113-119
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• 2020

Objective: The vibration device is one of the most commonly used warm-up devices not only for healthy athletes but also for healthy individuals. Therefore, this study aimed to investigate the immediate effects of local vibration on ankle plantar flexor muscle activation and peak torque in healthy adults. Design: One-group pretest-posttest design. Methods: This was a single-group study comprising a total of 36 (16 males and 20 females) participants. The average age of the 36 participants was 22.3 years. All the participants' concentric and eccentric peak torques of the gastrocnemius lateralis muscle were measured using an isokinetic device. Simultaneously, the participants' muscle activity was measured by surface electromyography. After the pre-experimental data were collected, the participants comfortably sat on the prepared chair with their hips and knees flexed to 90°. While in sitting position, local vibration was applied for 10 minutes using a 1:1 ratio intermittent pulsing mode device based on a previous study. Then, the post-experimental data were collected immediately after the local vibration by performing a similar process performed during the pre-experimental data collection. Results: The results showed a significant difference in muscle activity and eccentric peak torque (p<0.05). On the contrary, concentric peak torque values showed an insignificant difference with pre- and post-value. Conclusions: The results of this study demonstrated that local vibration can be possibly considered as one of the effective ways to increase ankle plantar flexor muscle activity and muscle performance, specifically the eccentric peak torque, in healthy adults.

• 한국통신학회논문지
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• 제35권4B호
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• pp.677-686
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• 2010

본 논문에서는 유무선 통합 환경의 차세대 방통융합 서비스를 위한 기반 기술로서 다양한 액세스 망에 대한 다중 접속 인터페이스를 갖는 멀티모드 단말의 인터페이스 가상화 기법을 소개한다. 제안된 가상 인터페이스 기술은 멀티모드 단말의 각 물리 인터페이스에 대해 상이한 IP 주소를 할당하고 패킷 전달 시 이들 주소간의 변환을 수행하는 기존의 방식과 달리, 고정된 하나의 단일 IP 주소 만을 이용하여 다수의 물리 인터페이스들을 가상화하는 기능을 제공한다. 따라서 패킷 전달 시 IP 주소 변환 등 단말 기능 변경을 요구하지 않으므로 Proxy MIP와 같은 네트워크 기반 IP 이동성 제어 기술과 연계하여 적용하기에 용이한 장점을 제공한다. 또한 기존의 OS가 단일 단말 내의 상이한 물리 인터페이스에 대해 동일 IP 주소를 할당할 수 없도록 하는 제약사항을 극복함으로써 MBB(Make-Before-Break) 방식의 핸드오버 제어뿐만 아니라 BBM(Break-Before-Make), 다중 접속(Multi-connection) 등과 같은 다양한 방식을 모두 지원할 수 있는 장점을 갖는다. 제안된 가상 인터페이스는 네트워크장치 인터페이스 표준 규격으로 개발된 NDIS 라이브러리를 이용하여 구현되었으며, 테스트베드 구축과 시험 프로그램 개발을 통해 주요 기능의 시험 및 동작 결과를 확인할 수 있었다. 이러한 가상 인터페이스를 통해 멀티모드 단말이 이종 액세스 망간 핸드오버를 수행하는 도중에도 동일한 IP 주소를 이용하여 실시간 멀티미디어 서비스 세션을 끊김없이 유지하도록 지원하는 것이 가능하다.

• 한국콘텐츠학회논문지
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• 제22권10호
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• pp.47-58
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• 2022

본 연구는 정규체육 수업에 활용되고 있는 티볼 스포츠를 스크린이 설치된 실내공간에서 체험할 수 있는 실감 콘텐츠 접근 과정 및 이를 적용한 개발사례를 제시하였다. 해당 연구는 초, 중학교 가상현실 스포츠실의 구기 스포츠훈련으로 지속적인 체육수업에 활용될 수 있다. 접근 내용을 살펴보면 티볼교재의 기초훈련내용을 중심으로 스포츠 전문가, 티볼 지도자의 자문기반 협업을 통하여 이용자에게 티볼 스포츠훈련 향상이라는 지속 가능한 교육에 적합한 훈련 접근 체계성을 제시하였다. 즉, 단순히 체험기반의 실감 콘텐츠가 아닌 초등학생에게 티볼 스포츠 수업의 몰입 유도와 자연스러운 기초훈련이 될 수 있도록 훈련 모드를 설계하였다. 개발된 훈련 콘텐츠는 주 차별 커리큘럼에 따라서 공격 기본훈련이 이루어지도록 하였으며 훈련 과정상에서 난이도별 목표에 따른 평가 피드백을 제시하여 이용자가 스스로 훈련향상을 할 수 있는 훈련모드 접근 과정을 제시하였다. 또한, 티볼 스포츠의 경기 규칙을 반영한 대전경기 모드 접근 과정을 제시하였다. 본 연구를 통해서 구기 스포츠의 기본훈련 및 신체 운동 향상이 될 수 있는 기능성 실감 콘텐츠 사례 및 실감 콘텐츠 개발 관련 산업체에 참고 제작사례로 제시될 수 있다.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1258-1258
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• 2001

Estimation of sugar and reducing sugar content in molasses is very important task in sugar refineries. Conventional methods of determination of sugar content in molasses samples are highly time consuming and employ hazardous chemicals. Due to the physical properties of molasses, probability of error in conventional analytical techniques is high. These methods have proven to be inefficient for a process control in any sugar industry. Hence development of a rapid, inexpensive, physical and also accurate method for sugar determination in molasses will be highly useful. Near Infrared spectroscopy is being widely used worldwide as an analytical technique in food industry. The technique offers the advantage of being non-destructive and rapid. The present paper highlights the potential of near infrared reflectance spectroscopy as a rapid and automated analytical technique for determination of sugar and reducing sugar content in molasses. A number of molasses samples were collected during and after the sugar season from Havana Sugar Industry, Havana. The samples were chosen so as to obtain a wide range of concentration of sugar and reducing sugars. This was done in order to achieve a good calibration curve with widely spread data points. These samples were scanned in the region of 1100 - 2500 nm in diffuse reflectance mode. An indigenous ELICO NIR spectrophotometer, modified according to the requirements of sugar industry was used for this purpose. Each sample was also analyzed simultaneously by standard chemical methods. Chemical values were taken as reference for near infrared analysis. In order to obtain the most accurate calibration for the set of samples, various mathematical treatments were employed. Partial Least Square method was found to be most suitable for the analysis. A comparison is made between the actual values (chemical values) and the predicted values (NIR values). The actual values agree very well with the predicted values showing the accuracy of the technique. The validity of the technique is checked by predicting the concentration of sugar in unknown molasses samples using the calibration curve. The present investigation assesses the feasibility of the technique for on-line monitoring of sugars present in molasses in sugar industries.

• The Journal of Korean Physical Therapy
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• 제26권5호
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• pp.324-330
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• 2014

Purpose: The aim of the current study was to compare the muscle architecture of lower extremity using rehabilitative ultrasound imaging (RUSI) in young adults in Seoul and Hanoi. Methods: The study design was a comparative study of muscle cross-sectional area of lower extremity. Sixty healthy young subjects (Seoul group: 30, Hanoi group: 30) participated in this study. Real-time B-mode RUSI with a 7.5MHz linear transducer was used for measurement of cross-sectional area, pennation angle, and muscle thickness of the rectus femoris, tibialis anterior, and medial gastrocnemius muscles. Independent t-test was used for statistical analysis. Results: Significant difference in cross sectional area of rectus femoris was observed between Korean young adults and Hanoi young adults (p<0.01). Muscle thickness and pennation angle of tibialis anterior in Korean young adults were greater than in Hanoi young adults (p<0.01). In addition, the muscle thickness and pennation angle of the medial part of gastrocnemius muscle were greater in Korean young adults than in Hanoi young adults (p<0.01). In addition, in the results for gender, men had larger muscle architectures than women in both groups (p<0.01). Conclusion: This study, using RUSI, showed significant difference in muscle architectures of lower extremity in a diverse group of young adults RUSI.

• 한국정보과학회논문지:시스템및이론
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• 제34권12호
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• pp.618-629
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• 2007

본 논문에서는 64비트 다중-코어 컴퓨팅 환경에서 효과적인 메모리 테스트를 위한 가상화 커널을 제안한다. 이때 효과적이라는 용어는 커널이 존재하는 메모리 공간을 포함한 모든 물리 메모리 공간에 대한 테스트를 시스템 리부팅 없이 수행할 수 있음을 의미한다. 이를 위해 가상화 커널은 4가지 기법을 제공한다. 첫째, 커널과 응용이 물리 메모리를 직접 접근 할 수 있게 하여 원하는 메모리 위치에 다양한 메모리 테스트 패턴을 쓰고 읽는 것이 가능하게 한다. 둘째, 두 개 이상의 커널 이미지가 다른 메모리 위치에서 수행 가능하도록 한다. 셋째, 커널이 사용하는 메모리 공간을 다른 커널로부터 격리한다. 넷째, 커널 하이버네이션을 이용하여 커널 간에 문맥 교환을 제공한다. 제안된 가상화 커널은 인텔사의 Xeon 시스템 상에서 리눅스 커널 2.6.18을 수정하여 구현되었다. 실험에 사용된 Xeon 시스템은 2개의 Dual-core CPU와 2GB 메모리를 탑재하고 있다. 실험 결과 설계된 가상화 커널이 메모리 테스트에 효과적으로 사용될 수 있음을 검증할 수 있었다.