남녀 아동의 성장기별 생체전기임피던스벡터와 위상각 분포

김혜진(Hyeoi Jin Kim),김철현(Chul Hyun Kim),정소정(So Chung Chung) 한국체육측정평가학회 2012 한국체육측정평가학회지 Vol.14 No.1

이 연구는 소아청소년에서 성별과 연령에 따른 위상각과 생체전기임피던스벡터의 수준과 위치를 구하고자 하였다. 또한 연구결과를 바탕으로 위상각과 생체전기임피던스벡터가 소아청소년의 성장수준과 성별에 따른 신체구성 및 체형의 변화에 대한 정보를 제공하고자 하였다. 연구의 목적을 위해 만 6세에서 14세의 건강한 소아청소년 1,270명을 동원하여 신체계측과 생체전기저항법을 측정하여 인체저항과 리액턴스를 측정하였으며, 임피던스 및 위상각과 그래프 상에 임피던스벡터의 분포를 분석하였다. 연구결과 BMI분포 중 67백분위 이상에 대한 임피던스벡터는 유의하게 최좌측 좌표에 분포하였고, BMI 33백분위수 이하는 임피던스벡터의 포물선이 최우측 좌표에 위치하였다. 이와 동시에 위상각은 BMI의 증가와 함께 유의하게 증가했다. 성장기에 따른 여아와 남아의 임피던스 벡터와 위상각은 6~8세에서는 남·여 간의 유사하게 나타났고, 9~11세에서 여아가 남아보다 좌측에 위치하였으며, 12~14세에서 여아의 임피던스벡터는 남아보다 좌측 좌표에 위치하였다. 이때, 위상각은 6~8세에서 남아가 유의하게 높은 수준을 가졌고 연령이 증가한 9~11세에서 보다 증가하였으며, 12~14세에서 여아와 남아 간의 수준은 유사한 수준으로 회귀하였다. 이상의 결과에서 BIVA와 위상각은 성장에 의한 체형과 체세포의 증가를 구분하여 소아청소년의 신체구성을 평가 할 수 있었다. Bioelectrical impedance analysis (BIA) gives resistance (R) and reactance (Xc). R and Xc normalized by body height (H) can be plotted as a bivariate vector (R/H versus Xc/H). R and Xc can also give phase angle. Vector BIA and phase angle is useful for studying the determinants of body composition. We investigated the effect of age or growth of children on BIA results including R, Xc, Z, and phase angle and its relevance to body-composition analysis in a large database of impedance vector distribution stratified by age, sex, and body mass index (BMI) for identifying the possibility to use BIVA and phase angle for children`s growth curve. We recruited 1,279 children aged 6 to 14. First, these children were divided by three groups according to BMI tertile value. Impedance vectors and phase angle were analyzed based on three BMI groups. These children were also divided into three age groups (6-8year group, 9-11year goup, 12-14year group). Impedance vectors and phase angle were analyzed based on three age groups by sex. As results, the impedance vector distribution pattern was influenced by sex, BMI, and age, with shoter vectors in males than females (p<0.001) and shorter vectors with increasing BMI (p<0.001). Phase angle gradually increased with increasing BMI (p<0.001). However, phase angle were larger in men than in women until 11 years old. Phase angle in female aged 12 to 14 years become similar to that in male aged 12 to 14 year. These results suggest that impedance parametes, BIVA, and phase angle can predict children`s growth and body composition. We could recommend that BIVA pattern can be developed for growth curve of children and adolescent.

로봇형 보조기 착용시 경사로에 따른 LSTM 기반의 보행패턴인식

김태희,이종명,권익중,심우섭,안동영,양혜은,최준호,박재환,손충현,김태환 한국재활복지공학회 2023 재활복지공학회논문지 Vol.17 No.3

In this study, the joint angle difference and the classification accuarcy of gait phase detection according to the ramp in the gait with the robotic orthotics were analyzed. Nine subjects were recruited, put on the robotic orthosis, and walked uphill, downhill, and level ground five times, respectively. During walking, three inertial sensors were attached to the human limb’s thigh, calf, and foot, and two inertial sensors were attached to the thigh and calf parts of the robotic orthotisis to measure the ankle and knee angles, respectively. The measured joint angles from the robotic orthotisis and the body limb were compared using SPM(Statistic Parameter Mapping) and trained to classify whether the stance phase or swing phase using LSTM(Long Short-Term Memory) classifier. As a result, the differences in the joint angle between the robotic orthotisis and the body limb were observed in the mid-stance and the mid-swing phase during gait. In addition, misclassification was observed during the change of stance phase and swing phase period. In particular, it was found that the number of misclassifications increased as the difference in joint angle between the robotic orthotisis and the body limb increased in the stance phase. Through this, the difference of joint angle between the robotic orthotisis and the body limb, which occurs along the ramp, affects the accuracy of gait phase detection. It is supposed to develop a phase detection and control algorism considering the effect of classification accuracy due to the difference in joint angle according to the slope change. 본 연구에서는 로봇형 보조기의 보행에서 경사로에 따른 관절각의 차이를 확인하고, 그 차이가 보행단계의 검출에 미치는 영향에 대해 분석하고자 하였다. 9명의 피험자를 모집하여 로봇형 보조기에 탑승시킨 후 각각 오르막 5회, 평지 5회, 내리막 5회의 보행을 진행하였다. 보행하는 동안 3개의 관성 센서를 신체의 대퇴, 종아리, 발에 부착하였고, 2개의 관성 센서를 로봇형 보조기의 대퇴부, 종아리부에 부착하여 로봇형 보조기와 신체의 발목 및 무릎각도를 측정하였다. 측정된 관절각도는 SPM(Statistic Parameter Mapping)을 사용하여 로봇형 보조기와 신체의 관절각을 비교하였고, LSTM(Long Short-Term Memory) 분류기를 사용하여 입각기와 유각기의 구분을 위하여 학습되었다. 그 결과, 보행을 진행하는 동안 중간 입각기와 중간 유각기에서 착용형 로봇형 보조기와 신체간의 관절각 차이가 확인되었다. 또한, 보행 단계의 검출 결과, 입각기와 유각기간 변화하는 동안 오분류가 확인되었다. 특히, 입각기 구간에서 로봇형 보조기와 신체의 관절 각 차이가 커짐에 따라 오분류의 횟수가 증가하는 것으로 나타났다. 이를 통해 본 연구에서는 경사로에 따라 발생하는 로봇형 보조기와 신체의 관절 각 차이가 보행 단계를 검출하는 데에 영향을 주는 것을 확인하였으며, 추후 보행단계 제어시 경사로에 따른 인체 분절과 유격으로 인한 분류 정확도의 영향을 고려하여 제어알고리즘을 개발할 것을 제안한다.

7상 BLDC 전동기의 고속 운전시 개선된 진상각 보상 연구

金現哲(Hyun-Cheol Kim),吳亨植(Hyung-Sik Oh),金長睦(Jang-Mok Kim),金喆遇(Cheul-U Kim) 대한전기학회 2007 전기학회논문지 Vol.56 No.11

According to previously published paper the phase advance angle is adopted to the BLDC motor drive with high speed. The report proposed describes the optimum algorism that phase current is in phase with the initial flat region of back EMF. This report studies the need of more leading phase advance angle compared with in phase concept between phase current and back EMF. In case of high reactance this report proposes the more phase advance angle than in phase. The test results more rms value of phase current and output power due to more phase advance angle than in phase. It will be helped the high power operation of BLDC motor at high speed.

Study on verification of AFE rectifier control for electric propulsion ship

윤경국 한국마린엔지니어링학회 2021 한국마린엔지니어링학회지 Vol.45 No.6

Electric propulsion ships are frequently subject to fluctuations in the generator output voltage and current due to load vari-ations from unpredictable environmental changes, including those of the maritime environment. The variation in the generator output affects the detection of the phase angle of the supply voltage, which is a key factor in the control of the active front end (AFE) rectifier of an electric propulsion system. In this study, an improved supply voltage phase-angle controller was proposed and applied to accu-rately detect the supply voltage phase angle required for the control of the AFE rectifier. The controller can be applied even under fluctuations in the output voltages of the generator owing to various circumstances that may arise in the electric propulsion ship. To demonstrate the effectiveness of the proposed improved supply voltage phase-angle controller, an irregular waveform with harmonics and zero-crossing in the output voltage of the generator was arbitrarily generated and inserted into the phase-angle detector. The pro-posed supply voltage phase-angle controller promoted a remarkable improvement in the phase-angle detection performance compared with that of the zero-crossing technique, a conventional method of phase-angle detection, even under irregular variations in the output voltage of the generator.

철봉 몸 접어 앞돌며 360° 슈트 기술동작의 운동학적 분석

이용식 ( Yong Sik Lee ) 한국스포츠정책과학원(구 한국스포츠개발원) 2010 체육과학연구 Vol.21 No.4

이 연구는 체조 철봉 동작 중 슈트 동작에 대한 3차원 영상분석을 통하여 운동학적 변인들을 분석하고, 그 결과들을 통하여 체조 지도자와 슈트 기술을 습득하고자 하는 선수들에게 슈트 동작에 대한 기초자료를 제공하는데 연구의 목적을 두었다. 그에 따른 결론은 다음과 같다. 첫 번째, 슈트 동작을 수행하는데 소요된 총 시간은 1.409초였고, P4가 가장 긴 소요시간을 보였으며, P1, P2, P3 순으로 나타났다. P4에서 가장 긴 시간이 나타난 것은 신체중심이 수직으로 상승하여 한 손으로 바를 잡고 360° 회전 동작이 이루어져야 하기 때문에 많은 시간을 확보하여 수행하는 것으로 나타났다. 두 번째, 신체중심의 이동변화 및 속도의 변화는 하강구간에서는 상승구간으로의 연결을 위하여 수직속도가 가장 빠르게 나타났다. 상승구간에서는 전후 속도와 수직 속도가 빠르게 나타나 하강시 발생한 원심력을 극대화 시킨 것으로 나타났다. 연결구간에서도 회전구간으로의 연결을 위하여 수직속도가 높게 나타났다. 회전구간에서는 신체중심의 움직임을 최소화 한 상태에서 회전 동작을 수행하기 때문에 신체중심의 속도가 가능 느리게 나타났다. 세 번째, 슈트 동작을 수행하는 동안 E2에서 E4까지의 고관절각도의 변화를 살펴보면 E2에서 고관절을 최대로 굴곡 시킨 후 신체중심이 상승하면서 E4에서는 점차 신전되어 각도가 크게 나타났다. E2에서 E4까지의 구간은 상승하는 구간으로 고관절을 최대한 빨리 신전시켜 다음 동작인 회전 구간으로의 연결이 중요한 구간이므로 나타난 결과라고 판단된다. 네 번째, 슈트 동작을 수행하는 동안 E4에서 E5까지의 회전구간에서는 최대한 빨리 어깨를 회전시켜 어깨와 좌우축이 평행하도록 위치시킨 후 다음 동작으로의 연결이 자연스럽게 되도록 하는 것이 중요한 구간이다. 분석구간 중 S1의 최고각속도가 S2의 최고각속도보다 빠르게 나타났다. 위의 결과들을 종합해 볼 때, 성공적으로 철봉 슈트 동작을 수행하기 위해서는 하강구간에서 원심력을 극대화시키고, 상승구간에서는 대퇴를 빠르게 신전시켜 상승 시 최대한 빠르게 신체중심의 위치가 위쪽으로 이동할 수 있도록 해야 한다. 또한, 회전구간에서는 어깨의 회전을 최대한 빠르게 회전시켜 양손이 다시 바를 잡을 때에 어깨가 좌우축과 수평을 이룰 수 있도록 하여 다음 동작으로의 연결이 자연스럽게 이루어질 수 있도록 해야 한다. 성공적인 슈트 동작을 수행하기 위하여 지도자들이 선수들에게 지도할 때에는 위의 사항들을 고려하여 지도해야 할 것으로 생각된다. The purpose of this study was to investigate the kinematics of the horizontal bar shoot 360° turn by using 3D motion analysis so as to provide information to increase the effectiveness of training and performance of the shoot movement. The results are as follows; ① The total time for the performance of the shoot was 1.409 ± 0.11s, for P1 0.342 ± 0.01s, P2 0.275 ± 0.01s, P3 0.059 ± 0.01s and P4 0.734 ± 0.09s. The time for the rotation phase was the longest because the gymnast`s hand needed to rotate 360°. ② The highest speed and largest range of motion for the center of mass (COM) occurred at the transition phase between the descending and ascending phase. For the ascending phase the anteroposterior and vertical speed was high due to the centripetal force created by the descending phase. For the connection/transition phase the vertical speed was high. At the rotation phase the COM movement was minimized and so the speed was slower then the other phases. ③ The maximum hip flexion during the E2 phase after then during the ascending phase E4 there was a gradual increase hip extension angle. The maximum flexion occurred here to increase the resulting speed which is especially important during the rotation phase. The average maximum hip angular speed was 460.65 ± 46.03°/s. ④ At the start of E4 the average shoulder angle was 21.54 ± 2.60° and at the end of E5 the rotation phase was 336.59 ± 19.15°. It was deemed that during the rotation phase it was important to rotate the shoulder horizontally as quick as possible to ensure a smooth and natural movement. The shoulders angular rotation velocity was 858.40 ± 289.99°/s, and the at S1 this was shown to be 1063.45°/s. To summarize the above results for a successful shoot movement centripetal force must be maximized during the descending phase, and fast hip extension during the ascending phase. At the transition phase fast shoulder angular rotation is needed for the hands to grab the bar for a smooth and natural motion. While teaching the shoot movement the above suggestions should be taken into consideration.

Phase Plane상의 안정경계 및 횡력 포화경계를 이용한 차량 안정성 해석

홍대건(Daegun Hong),허건수(Kunsoo Huh),박장현(Jahng-hyon Park),조동일(Dong-il Cho) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

It is known that the instability of a vehicle is caused by nonlinear characteristics of a tire and depends heavily on the rear tire force saturation. In this paper, the vehicle stability is analyzed using this phase plane method and this analysis is expanded to the 3-dimension including the steering angle. As a result, the 3-D stable boundary is constructed with respect to side slip angle, rate of side slip angle and steering angle. In the lane change maneuvers of a vehicle, the stable margin is monitored by comparing the trajectory of vehicle's side slip angle and steering angle with the 3-D stable boundary. This stable margin can be utilized as an index in order to estimate a vehicles' stability. Also, the lateral tire force saturation is analyzed and the saturation boundary is determined in the phase plane. It is confirmed that this saturation boundary is located inside of the stable boundary and the non-saturation region of the lateral tire force is smaller than the vehicle stable region.

Optimal Phase Angle Design for the Lunar Lander

Dong-Hyun Cho,Hae-Dong Kim 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

To design the optimal lunar landing trajectory, the periapsis of de-orbit burn phase is usually used as a starting point of the powered descent phase. And the optimal problem is constructed based on the initial states at this point. For this optimal problem, some kinds of result trajectories have the increase in their own altitude at the early stage to earn the enough time to reduce their huge horizontal velocity for the low thrust, and this phenomenon increase the consumption of the propellant mass. For this reason, it is possible to exist another phase angle to reduce this phenomenon instead of zero for periapsis of de-orbit burn phase because the vertical velocity is not zero at this point. To find out this optimal phase angle, in this paper, the initial free state optimal problem method is applied without any additional assumption and change of hardware for the traditional optimal lunar landing problem. Using this approach, it shows that the optimal phase angle does not always equal to the periapsis for some cases, and it is possible to reduce the fuel consumption of the lunar lander.

Estimation of Optimum Flip Angle using 3D VANE XD Technique: Focused on Pre-Contrast and Hepatobiliary Phase

Eun-Hoe Goo 한국자기학회 2022 Journal of Magnetics Vol.27 No.2

To investigate the optimum flip angle that can enhance image quality, SNR (signal to noise ratio), and CNR (contrast to noise ratio), comparing the images obtained, applying flip angles, 11°, 14°, 17°, 20°, and 23° in getting Liver Hepatobiliary Phase image using 3D VANE XD(3D Multivane mDixon, Philips Healthcare) technique. Experiments were conducted on a total of 30 outpatients and inpatients to our hospital (HCC:10, Metastasis:10, Abscess:10). As for the equipment used in the experiments, Philips Ingenia 3.0T CX was used, and all parameters other than the flip angle were set the same to conduct the tests. As for the image analysis method, using the Image-J program (National Institutes of Health and LOCI), the SNR of the liver, kidney, and pancreas obtained from the images by flip angle before the contrast medium injection and the CNR between the lesion and the normal tissue after the contrast medium injection were measured to conduct comparative analysis. As a result of a comparison of images before and after the contrast medium injection by disease, when the flip angle of 17° was applied, SNR and CNR were measured higher than in the images of other flip angles (p<0.05). In the comparisons of the images taken before and after the injection of contrast medium by disease, when a flip angle of 17° was applied, the SNR before contrast medium injection was 28-29 % higher, and the SNR after the injection of contrast medium was 11 % up to 49 % higher than that at other flip angles. There was a difference in CNR before contrast medium injection of 30-43 % and CNR after contrast medium injection of 58-68 %. The measured value increased up to 17° and then decreased after that. Additionally, in the qualitative evaluation, Lesion Conspicuity (p=0.003), Image Artifact (p=0.0001), Lesion Delineation (p=0.0002), and Vascular Anatomy (p=0.0002) received the most excellent evaluations at 17°. In conclusion, in this study, the flip angle of 17° provided the highest SNR and CNR values when the tests were conducted using the free breath hold technique, 3D VANE XD Sequence. Thus, in liver MRI protocol tests, the overall diagnostic information was provided, including hypervascular tumor.

Band-Selective Simulation of Photoelectron Intensity and Converging Berry Phase in Trilayer Graphene

Hayoon Im,Sue Hyeon Hwang,Minhee Kang,Kyoo Kim,Haeyong Kang,Choongyu Hwang 한국진공학회(ASCT) 2024 Applied Science and Convergence Technology Vol.33 No.4

The Berry phase is one of the key elements to understand quantum-mechanical phenomena such as the Aharonov-Bohm effect and the unconventional Hall effect in graphene. In monolayer and bilayer graphene the Berry phase has been manifested by an anisotropic distribution of photoelectron intensity along a closed loop in the momentum space as well as its rotation by a characteristic angle upon rotating light polarization. Here we report a band-selective simulation of photoelectron intensity of trilayer graphene to understand its Berry phase within the tight-binding formalism. ABC- and ABA-stacked trilayer graphene show characteristic rotational angles of the photoelectron intensity distribution, as predicted from their well-known Berry phases. Surprisingly, however, in ABA-stacked trilayer graphene, the rotational angle changes upon approaching the band touching point between the conduction and valence bands, suggesting that the Berry phase changes as a function of the binding energy. The binding energy-dependent Berry phase is attributed to enhanced hybridization of the two electron bands of ABAstacked trilayer graphene that merge at the band touching point, resulting in a converging Berry phase. These findings will provide an efficient way of tuning the Berry phase and hence exotic phenomena stemming from the Berry phase.

진공청소기용 유니버셜모터의 고조파전류 저감 위상각제어기 설계

임홍우,장용해,백형래 전력전자학회 2002 전력전자학회 논문지 Vol.7 No.3

단상 위상각제어시스템의 경우 제어기의 구조상의 단순함과 저가격화로 인해 많은 노이즈가 발생함에도 불구하고 트라이액 교류 위상각제어기를 속도제어기로 사용하고 있다. 시판되는 진공청소기의 경우 트라이액의 위상각을 조절하여 속도를 제어하고 있는데 고조파전류의 발생을 최소화로 하기 위해서 속도의 선형성을 고려하지는 않고 제작하고 있는 경우가 대부분이다. 본 논문에서는 진공청소기용 위상각 제어기에 파라미터 추정에 의한 실제작 시스템으로 고조파가 많이 발생되는 특정 트라이액 트리거 위상각에서도 고조파전류가 효과적으로 감소되고 부수적으로 지연각이 없어지는 고조파전류 감쇠용 위상제어기의 설계 및 제작하여 실험을 통해 입증하였다. The single phase angle control system may become noisy when speed Is modulated with a conventional TRIAC AC controller. But this system is widely used despise of occurring sub-harmonic current because of its simply structure and low cost. Most of the vacuum cleaner drive control system regulates TRIAC's phase angle, so that it is controlled the speed. In the case of marketing product, it is not considered linearity of the speed to minimize occurring harmonic current. The sub-harmonic current reduces effectively in regulating specification TRIAC trigger phase angle. In this paper, we examined about characteristics of phase angle controller and parameter of parallel coil for eliminating sub-harmonic current.