• Physical Therapy Rehabilitation Science
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• 제8권2호
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• pp.61-66
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• 2019

Objective: The purpose of this study was to investigate the effects of resistance applied in various directions on lower extremity muscle activity and balance during squat exercise performance. Design: Cross-sectional study. Methods: Forty-one adults (19 males and 22 females) agreed to the study purpose and procedures. All subjects randomly performed squat exercises with an intensity of overcoming 10% of body weight resistance pulled forward, backward and general squats with $60^{\circ}$ of knee joint flexion. Electromyography was used to measure muscle activity of the vastus medialis oblique (VMO), rectus femoris (RF), vastus lateralis oblique (VLO), biceps femoris (BF), and semitendinosus (ST) muscles. The Wii Balance Board was used to assess balance during the three-method squat operation. Each operation was measured three times for 10 seconds. Results: There were significant differences in muscle activities of the VMO, RF, VLO, ST and balance ability with the application of three directions of resistance (p<0.05). Post hoc comparisons revealed that squats performed with resistance pulled in the backward direction resulted in higher VMO, RF and VLO activity than with the resistance placed in a pulled forward direction (p<0.05). In the ST, resistance applied in the pulled forward direction showed greater muscle activity compared to the pulled backward direction (p<0.05). With balance, squats performed with resistance pulled in the forward direction showed greater muscle activity than with resistance applied in the pulled backward direction and during general squat performance (p<0.05). Conclusions: In this study, squat exercises performed with resistance applied in the direction of pulling backwards was found to be the most effective in improving quadriceps muscle strength and balance. It is effective to provide resistance that is placed in the forward when it is difficult to perform a general squat due to weakness of the quadriceps.

• 한국추진공학회지
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• 제22권6호
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• pp.111-117
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• 2018

마이크로 추력기의 성능평가를 위해 MEMS 추력 측정 시스템을 설계하였으며, 시스템의 성능 예측에 관한 연구를 수행하였다. 추력 측정 시스템은 빔, 박막, 압저항 센서로 구성된다. 시스템의 안정성 검증과 빔의 응력 변화를 확인하고 압저항 센서의 크기 및 위치 선정을 위해 FEM 해석을 수행하였다. 재료의 허용응력과 최대응력을 비교하여 설계한 시스템들의 안정성을 검증할 수 있었다. 압저항 센서는 높은 게이지 계수를 확보하기 위해 빔의 길이의 20%로 설계 하였으며, 기준형상의 박막과 빔의 크기는 각각 $15mm{\times}15mm$, $500{\mu}m{\times}500{\mu}m$로 설계하였다.

• 대한물리치료과학회지
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• 제25권3호
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• pp.17-24
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• 2018

Purpose: The purpose of this study was to investigate the effect of whole body vibration combined breathing resistance on lung capacity and respiratory muscle and to suggest a mediation method for improvement of respiratory function and lung function in the future. Methods: This study was a preliminary study design of two groups of 54 healthy young adults who were randomly assigned to an experimental group (n=27) with core exercise combined with respiratory resistance and whole body vibration and a control group with respiratory resistance and core exercise (n=27). All interventions consisted of 6 core exercises every 40 seconds and rest for 20 seconds. To compare the effects of intervention, we measured spirometry and respiratory muscle strength. Results: Both the experimental group and the control group showed a significant increase in Forced vital capacity (FVC) and Maximum voluntary ventilation (MVV) (p<.05). However, FEV1 and FEV1% were significantly increase only in the experimental group (p<.05). FVC, FEV1%, Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP) showed more significant increase in the experimental group than the control group. Conclusion: These findings indicate that whole-body vibration combined breathing resistance is an effective intervention for people, with FVC, FEV1%, MIP, MEP increase.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.624-637
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• 2019

A semi-submersible offshore platform always operates under complex weather conditions, especially wind and waves. It is vital to analyze the structural dynamic responses of the platform in short-term sea states under the combined wind and wave loads, which touches upon three following work. Firstly, a derived relationship between wind and waves reveals a correlation of wind velocity and significant wave height. Then, an Improved Mixture Simulation (IMS) method is proposed to simulate the time series of wind/waves accurately and efficiently. Thus, a wind-wave scatter diagram is expanded from the traditional wave scatter diagram. Finally, the time series of wind/wave pressures on the platform in the short-term sea states are converted by Workbench-AQWA. The numerical results demonstrate that the proposed numerical methods are validated to be applicable for wind and wave simulations in structural analyses. The structural dynamic responses of the platform members increase with the wind and wave strength. In the up-wind and wave state, the stresses on the deck, the connections between deck and columns, and the connection between columns and pontoons are relatively larger under the vertical bending moment. These numerical methods and results are wished to provide some references for structural design and health monitoring of several offshore platforms.

• 한국표면공학회지
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• 제55권6호
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• pp.448-459
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• 2022

Generally, steel is the most commonly used in the industry because of good strength, processability and cost-effectiveness. Steel can be surface-treated such as coating or used as an alloy by adding elements such as Cr, Ni, Zr, and Al to increase corrosion resistance. However, even if steel is used in same environment corrosion resistance is sharply lowered when it is exposed to a high temperature for a fixed or extended period of time due to an overload or other factors. In particular, the use of hot-dip aluminized plated steel, which is used in high-temperature atmospheres, is increasing due to the surface Al₂O₃ oxide film. This steel necessitates an urgent solution as issues of corrosion resistance limitations often appear. It is an important issue that not only cause analysis but also the research for the surface treatment method that can be solved. Thus, in this study, Cr in which it is expected to be effective in corrosion resistance and heat resistance attempted to deposit on hot dip aluminized plated steel with PVD sputtering. And it was possible to present the surface treatment application of various types of industrial equipment exposed to high temperature and basic design guidelines for use by confirming the corrosion resistance of hot dip Al-Si plated steel with Cr film deposited at high temperature.

• 대한건축학회논문집:구조계
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• 제35권12호
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• pp.149-156
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• 2019

Recently, skyscraper building and apartment fires, which were rapidly spread out from a low floor to a rooftop, have become a frequent occurrence in mass media. This fire problems have a fatal disadvantage that the exterior wall finish of the building emits toxic gas in case of fire by using dry bit method or organic insulating material. Therefore, in order to remedy these problems, many exterior wall finishing construction methods have been proposed, but the current trend is to use existing construction methods due to problems such as economy, weight, and durability. On the other hand, in countries such as Germany and Japan, ceramic sidings are used as exterior finishing material for buildings, which is environmentally friendly, excellent natural beauty, long life, easy maintenance and high-quality exterior materials. However, those ceramic sidings have still the problems such as manufacturing cost and weight problem because of boosting the sintering temperature up to 1,350℃ or more. Also, conventional CRC, MgO, FRP sidings which are composed of pulp, glass fiber and organic materials, have been reports of deformation due to ultraviolet rays, discoloration, corrosion and scattering, surface rupture, lifting and peeling. Therefore, in this study as an alternative to solve this problem, halosite nano kaolin produced in Sancheong in Korea and frit flux were used to satisfy the required properties as ceramic siding using low temperature sintering (below 1,000℃) and lightweight materials such as pearlite. This study aims to design the optimal formulation and process of materials and to study the characteristics of nano-coated ceramic siding material development and to present relevant basic data. The findings show that ceramic siding for nanocoated building materials is excellent as a natural ceramic siding building material. The fire resistance of natural minerals and nano particle refining technology satisfy the bending strength of 80kgf / cm2, the volume ratio of 2.0 and the absorption rate of less than 10.0%.

• 한국정보통신학회논문지
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• 제25권1호
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• pp.75-80
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• 2021

측위 기술은 증강현실, 스마트 팩토리, 자율주행 등에서 중요한 기능을 수행하고 있다. 측위 기술 중에서 비콘을 이용한 측위 방법은 RSSI(Receiver Signal Strength Indicator) 값의 편차로 인하여 도전적인 과제로 여겨져 왔다. 본 논문에서는 수신기의 RSSI 값을 입력으로 하고 거리를 목표 값으로 하는 신경망을 학습시켜서 이동하는 객체에 대한 위치를 예측하였다. 이를 수행하기 위해 RSSI 대비 거리 실측값을 수집하였다. 수집한 데이터로 합성 데이터를 만들기 위한 신경망을 도입하였다. 이 신경망을 바탕으로 거리 대비 RSSI 값을 예측하였다. 합성 데이터를 바탕으로 가상으로 좌표계를 구성하여 객체의 위치를 예측하였다. 합성 데이터를 생성하기 위한 신경망으로 RSSI의 표준편차는 구하였고 이 값을 기반으로 가상환경에서 단말의 위치를 추적하는 신경망을 학습시켜 객체의 좌표를 추정하였다.

• 한국지반환경공학회 논문집
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• 제12권2호
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• pp.45-53
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• 2011

쏘일네일 공법은 일반적으로 한계평형해석법을 토대로 검토한 사면안정해석결과를 이용하여 설계기준안전율 이상을 만족하면 안정한 것으로 판단하여 설계하고 있다. 그러나 쏘일네일의 길이가 짧은 경우 설계기준안전율을 만족하고도 발생변위가 과다하여 사용상에 문제가 발생하는 경우가 있다. 본 연구는 대형파괴재하시험결과에 의한 재하하중-안전율 및 재하하중-발생변위비와의 관계를 분석하여 쏘일네일 보강벽체의 안전율-발생변위비와의 상관관계를 분석하였으며, 분석결과 쏘일네일 보강벽체의 사용한계상태에 해당하는 발생 변위비 0.3% 이내를 만족하기 위해서는 한계평형해석에 의한 안전율이 최소 1.35 이상을 확보하여야 할 것으로 평가되었다. 또한 한계평형해석결과 최소 안전율 1.35 이상을 만족하여도 지반의 전단강도가 작거나 벽체높이가 높을 경우 사용한계상태에 해당하는 발생 변위비 0.3% 이내를 만족하지 못하는 경우가 있어 수치해석을 통한 발생변위 검토가 필요할 것으로 판단된다.

• 정보보호학회논문지
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• 제20권4호
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• pp.117-134
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• 2010

제품의 아이디를 자동적으로 신속하게 인식하기 위한 기술로 주목받았던 수동형 RFID 태그가 직면한 문제는 가격, 인식률뿐만 아니라 최근에는 인증, 데이터 보호 및 제품추적 문제로 확대되고 있다. 대표적인 수동형 RFID 기술은 900 MHz UHF 대역의 국제표준인 ISO/IEC 18000-6 타입 C 기술이다. 이 국제표준은 보안 해결책을 제시하지 않았기 때문에 진품 확인, 태그의 저장정보 보호 및 추적 차단 서비스에 활용하기 어려운 단점이었다. 본 논문에서는 인증, 데이터 보호 및 제품추적 문제 해결을 위한 ISO/IEC JTC l/SC 31의 국제표준화 동향을 살펴보고, 국제표준에서 요구하는 암호 엔진을 사용하는 높은 수준의 보안성을 만족하는 UHF 대역의 수동형 RFID 보안 프로토콜을 제안하고 그에 대한 보안성을 분석한다. 또한 국제표준 문서에 적용될 수 있는 수준의 명령/응답 구조와 암복호화 방법을 제시함으로써 그 구현 가능성을 검증한다.

• The Journal of Korean Physical Therapy
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• 제33권3호
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• pp.168-177
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• 2021

Purpose: This study applies the ICF to identify the patient's body function, structure, and participation, evaluates the patient's environmental factors and individual factors, and is a high level of movement to return to the society of patients with multiple ligament injury of the knee joint. Methods: Progressive strength training and ROM exercise were performed 30 minutes a day, 5 times a week for 6 weeks. The evaluation was performed by examining the ROM, length, MMT, instability, dynamic balance, pain and depression. Results: The ROM of the knee joint was improved from 110° to 135° after intervention, and the knee flexion length decreased from 69 cm to 45 cm. Knee flexor is Good after intervention from Poor-, and knee extensor is Good+ after intervention from Poor, and the plantar flexor of the ankle joint improved from Poor- before intervention to Good after intervention and dorsi-flexor of the ankle joint improve to Good from Poor. Pain index was moderate before and after the intervention, with a score of 3, 2 after the intervention, and when maintaining the sitting cross-legged, the before intervention score was 7 to 4 after the intervention. Conclusion: The patient's posture of sitting cross-legged was maintained from 30 seconds before intervention to 14 minutes after intervention. These results were able to set the hypothesis design, intervention method and goal that the multifaceted approach of environment and individual factors as well as body function and structure area, activity and participation area using ICF checklists, it is helped the patient to return to daily life.