• Korean Journal of Geomatics
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• 제2권1호
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• pp.57-64
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• 2002

Measuring the depth of water is very important in ensuring the protection and safety of seaside. There are many difficulties in making the contour bathymetric map, and contour line due to the limitation of continuous measurement of water depth and collimation with the conventional measuring and positioning methods. But the real-time kinematic GPS (RTK GPS) positioning using a carrier phase enables us to decide a precise position without breaking a signal even under the condition of a moving environment. It is also possible to obtain an accurate depth of water in real time with a fathometer through the measuring of time delay between sending and receiving epochs. This research aims at investigation of accuracy potential of RTK GPS in combination with Echo Sounder(E/S) for the coastal mapping. Apart from this purpose, the accuracy of ambiguity resolution with the OTF(On the Fly) method was tested with respect to the initialization time. The result shows that the accuracy is better than 1cm with 5-minute initialization in the distance of 10km baseline. The seaside topography was measured by the RTK GPS only, on the other hand the seafloor topography was surveyed in combination of RTK GPS and E/S. Comparing to the volume of seaside measured by RTK GPS and digital topographical map, the difference of only 2 % was achieved. This indicates that the coastal mapping with RTK GPS is successfully conducted. In addition it is also demonstrated that the 3-dimensional perspective model resulted from the undersea topography measured by RTK GPS and E/S is very close to that from the digital map. Through this study, it was verified that RTK GPS is to be very useful method in the analysis of coastal morphology owing to its capability of getting the precise DTM for the using of harbor reclamation, dredging, and the estimation of soil movement in a river.

• 한국기계가공학회지
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• 제18권9호
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• pp.72-80
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• 2019

In this task, the tool dynamometer design and manufacture, and the Ansys S/W structural analysis program for tool attachment that satisfies the cutting force measurement requirements of the tool dynamometer system are used to determine the cutting force generated by metal cutting using 3-axis static structural analysis and the LabVIEW system. The cutting power in a cutting process using a milling tool for processing metals provides useful information for understanding the processing, optimization, tool status monitoring, and tool design. Thus, various methods of measuring cutting power have been proposed. The device consists of a strain-gauge-based sensor fitted to a new design force sensing element, which is then placed in a force reduction. The force-sensing element is designed as a symmetrical cross beam with four arms of a rectangular parallel line. Furthermore, data duplication is eliminated by the appropriate setting the strain gauge attachment position and the construction of a suitable Wheatstone full-bridge circuit. This device is intended for use with rotating spindles such as milling tools. Verification and machining tests were performed to determine the static and dynamic characteristics of the tool dynamometer. The verification tests were performed by analyzing the difference between strain data measured by weight and that derived by theoretical calculations. Processing test was performed by attaching a tool dynamometer to the MCT to analyze data generated by the measuring equipment during machining. To maintain high productivity and precision, the system monitors and suppresses process disturbances such as chatter vibration, imbalances, overload, collision, forced vibration due to tool failure, and excessive tool wear; additionally, a tool dynamometer with a high signal-to-noise ratio is provided.

• 한국전자통신학회논문지
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• 제14권5호
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• pp.1009-1018
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• 2019

본 연구에서는 표면근전도 측정기 기반의 재활의료기기의 설계 및 구현에 관한 내용을 기술한다. 재활시스템은 BLDC모터와 모터 드라이브를 이용하여 제어된다. BLDC모터 드라이브는 동작제어를 하며, 속도는 외부 서보모터를 통해 드라이브를 제어한다. 또한 모터 외부에 결합된 포텐쇼미터는 모터에 의해 회전하는 부하 위치 정보를 전달한다. 재활 알고리즘은 환자가 일정 각도 범위에서 주기적인 수축 이완 재활운동을 속도단계별로 실행하며 재활운동 시 사용자 설정 단계에 따른 모터를 활용하여 $0{\sim}120[^{\circ}]$의 최대각도로 제한하여 제어한다. 보행 알고리즘은 양쪽 안쪽넓은근에 부착된 표면근전도 측정기로 획득한 신호의 차이 값을 이용하여 근전도 신호가 낮은 다리에 모터제어로 보상해주며 보행운동 시 모터와 표면근전도 측정기를 활용하여 $0{\sim}88[^{\circ}]$의 최대각도로 제한하여 제어한다.

• 대한조선학회논문집
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• 제57권1호
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• pp.35-44
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• 2020

Propeller cavitation extent, pressure fluctuation induced by cavitation, pressure distribution on propeller blade, total velocity distribution and nominal wake distribution for a MR Taker were computed in both conditions of model test and sea trial using a code STAR-CCM⁺. Then some of the results were compared with model test data at LCT and full-scale measurement (Ahn et al (2014); Kim et al (2014)] in order to confirm the availability of a numerical prediction method and to get the physical insight of local flow around a ship and propeller. The nominal wake distributions computed and measured by LDV velocimeter on the variation of on-coming velocity show the wake contraction characteristics proposed by Hoekstra (1974). The numerical prediction of propeller cavitation extent on a blade angular position and pressure fluctuation level on each location of pressure sensors are very similar with the experimental results.

• PNF and Movement
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• 제19권3호
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• pp.391-399
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• 2021

Purpose: As laptop use increases throughout the COVID-19 pandemic and its use outside of traditional workstations proliferates, it is imperative to expand the limited research available regarding ergonomic exposure. This study aimed to identify the effects of a laptop supporter on biomechanical characteristics in the wrist joint muscles of healthy young adults. Methods: This was a cross-sectional observational study design with thirty-four healthy young adults as participants. They conducted a typing exercise performed under two different conditions, which were with and without a notebook computer supporter. This study measured the biomechanical characteristics of the muscles of the wrist joints including the flexor carpi ulnaris (FCU), the flexor carpi radialis (FCR), the extensor carpi radialis longus (ECRL), and the extensor carpi ulnaris (ECU). Measurements were taken three times: before typing, immediately after typing for 30 minutes with a supporter, and immediately after typing for 30 minutes without a supporter. The statistical method to compare the three different measurement conditions was the repeated measures ANOVA. Results: The participants showed significantly different levels of dynamic stiffness in both the FCU before typing and immediately after 30 minutes of typing with a supporter, and showed significantly different levels of dynamic stiffness in the FCR before typing and immediately after 30 minutes of typing with a supporter. The dynamic stiffness level immediately after 30 minutes of typing without a supporter was significantly different than that immediately after 30 minutes of typing with a supporter. However, the muscle tone was not significantly different among the three different conditions. Conclusion: The results of this study revealed that a laptop supporter used to correct the eye level of the electronic screen increases the dynamic stiffness of the wrist joint flexors, so it is necessary to consider the neutral position of the wrist joint during typing.

• The Journal of Korean Physical Therapy
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• 제33권4호
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• pp.202-209
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• 2021

Purpose: This study examined whether various lower extremity exercises using a Swiss ball in the standing position could improve balance, muscle strength, gait, and fall efficacy in stroke patients. Methods: Twenty-one stroke patients were randomly divided into three groups, each with seven participants. For four weeks, experimental group 1 performed various lower extremity exercises using a Swiss ball, while experimental group 2 executed the same exercises without a Swiss ball, and the control group underwent general physical therapy. The subjects' knee extensor muscle strength, balance, gait, and fall efficacy were evaluated before and after the intervention using portable muscle strength measurement, the Berg Balance Scale (BBS), G-walk, and the Korean Falls Efficacy Scale (K-FES). Results: Knee extensor strength increased significantly in all three groups after the intervention; in particular, a significant increase was seen in experimental groups 1 and 2 compared to the control group. Moreover, all three groups had significantly better BBS scores and higher cadence after the intervention; notably, experimental group 1 had better scores and increased cadence than the control group. Additionally, gait speed was significantly increased in the experimental group 1 than in the control group. The step length of the non-affected leg was also significantly higher in the same group. The K-FES score improved significantly in all three groups, but there was no significant difference between the groups. Conclusion: This study suggests that lower extremity exercises with or without a Swiss ball could be effective interventions to improve muscle strength, balance, gait, and fall efficacy in stroke patients.

• 한국의류산업학회지
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• 제21권2호
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• pp.171-178
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• 2019

This study analyzed the pressure, subjective wearing comfort, and design preference of brassiere shoulder straps among women in their 20s and 40s. Experimental clothing was made by different shoulder strap designs on a brassiere. In the four designs (A-D), the front attachment points of the shoulder straps were the same, but the back attachment points were different. Three of them (E, E1, E2) were of a halter neck design, with different front attachment positions. The pressures of A-D were measured at the position passing through the shoulder line (P1), and E-E2 was measured at the back neck (P2) as well as at P1. Subjective wearing comfort and design preference were rated on a 7-point Likert scale. A was determined to exert the highest pressure at the neck side of the design in the pressure measurement analysis of A-E2, whereas E1 exerted the lowest. E was measured to have the highest pressure among the E-E2 designs, whereas E2 had the lowest. Participants preferred A the most and E the least in regards to the subjective wearing comfort of A-E. Thus, participants deem A to be the most comfortable despite the high strap pressure. However, E was the most favored design, despite its poor wearing comfort. Participants' subjective impressions of E-E2 were that E2 was the most uncomfortable, but its design was the most preferred. Consumers' design preferences and subjective impressions of wearing comfort did not match.

• 한국정보통신학회논문지
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• 제23권7호
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• pp.771-778
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• 2019

기존 단일 조도센서를 이용한 조도검출 방식은 좁은 FOV (Field of View) 특성 상 측정 위치에 따라 검출 조도의 균일도가 저하된다. 다수개의 조도센서를 통해 평균 조도값을 검출하는 방법은 복잡도 증가 및 계산과정에서 오류가 증가하는 문제점을 가지고 있다. 본 논문에서는 넓은 FOV를 가지는 하나의 이미지센서를 기반으로 한 조도검출 방법을 제안하였으며, 제안된 방법은 기존 조도센서가 가지는 시스템 복잡도, 오류 증가 등의 문제점이 해결 가능하다. 실내 환경에서의 성능평가 결과는 색차조도계 (CL-200A)를 이용한 기준값 대비 조도센서가 1개인 경우 평균 12%, 조도센서가 5개인 경우 평균 10.7%, 이미지센서의 경우 평균 6.2% 차이가 발생하는 것을 확인하였으며, 이를 통해 이미지센서를 기반으로 한 제안된 검출방법은 균일성이 향상된 공간조도를 간단하고 정확하게 검출할 수 있음을 확인하였다.

• 한국측량학회지
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• 제36권6호
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• pp.451-456
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• 2018

시설물의 유지 관리 및 모니터링에 UAVs (Unmanned Aerial Vehicles)의 활용이 확대되고 있다. 안전 점검을 위한 시설물의 외관 상태 평가를 위하여 고해상도 영상을 취득하는 것이 필요하며, 넓은 지역을 빠르게 취득하기 위하여 비디오 데이터로 취득할 필요가 있다. 일반적으로 비디오 데이터에는 위치 정보가 포함되지 않아, 검사 개체의 실제 크기에 대한 정량적 분석이 어렵다. 본 연구에서는 교량 시설물을 대상으로 비디오 프레임과 기준 사진의 정합을 이용하여 교량의 3차원 점군(point cloud) 데이터의 활용성을 평가하고자 한다. 드론을 이용하여 비디오와 사진을 취득하고, 기준 사진과의 특징점 정합을 통하여 비디오 프레임의 외부 표정 요소를 생성하였다. 실험 결과 비디오 프레임 데이터는 기준 사진과 유사한 표정 정확도를 얻었으며, 표정된 프레임 데이터를 이용하여 생성된 점군 데이터는 교량의 형상 및 크기를 잘 표현하였다. 향후 다양한 조건의 정합 실험을 통하여 결과물의 안정성이 확인되면, 비디오 기반의 시설물 모델링 및 점검에 효과적으로 적용될 것으로 기대된다.

• 한국전자파학회논문지
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• 제29권11호
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• pp.898-905
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• 2018

본 논문에서는 대지, 대공 표적을 포착 추적할 수 있는 적외선 및 가시광 센서가 탑재된 이종센서 영상탐색기의 종합 성능시험을 위해 구축한 HILS(Hardware In-the-Loop Simulation) 시스템 내에 적외선 표적원을 제안한다. 이 통합시스템은 다양한 종류의 표적과 시나리오 기반 이동 표적의 궤적을 모사하기 위해 열원 및 광원을 출력하는 100개의 모듈로 구성하였다. 또한 표적에 대한 위치, 속도, 방향, 배경 클러터와 재밍 환경 등을 모사할 수 있다. 이종센서 영상탐색기의 시험평가를 위해 구축된 HILS 시스템의 전체 시스템 구성과 적외선 표적원의 설계 및 측정 결과를 제시한다. 향후에, 구축된 HILS 시스템에서 모의비행 시나리오 기반으로 동적 실시간 포착 추적에 대한 단일 또는 이종센서가 탑재된 이종센서 영상탐색기의 성능을 시험할 예정이다.