性別 및 年齡에 따른 體格과 體力의 特性과 變化에 關한 縱斷的 硏究 Ⅰ : 體育專攻 大學生을 中心으로 Emphasised on College Men of Physical Education

金尙國,姜東洹,金昇一,徐再均,金耕知,孫斗玉,鮮于攝,崔榮烈,尹宇相,金亨燉,方永鎭,李錫元 慶熙大學校 體育科學大學 1988 體育科學論叢 Vol.- No.1

The purpose of this study was to compare the characterists and change in physique and physical function by college student of physical education major(287males and 40 females of age groups ranging from 18 to 26). The results were as following; 1) The characteristics of physique and physical function by sex and age. ① The male group of 18yrs old showed higher values in Height, Weight, Upper Limb Length, Strength, Flexibility, and Vital Capacity than any other groups, but female group showed lower values in Height, Weight, Chest Girth, Lower Limb Length, Thigh, Girth, Calf Girth and all of the Physical function. ② The male group of 19yrs old showed high values in power and Agility, then female group showed in Strength and Flexibility. ③ The male group of 20yrs old showed the lower values in Weight, Waist Girth, Upper Limb Length, Fore Arm Girth, Thigh Girh.Calf Girth, Vital Capacity, and female group are very lowed in Upper Arm Lenght, Fore Arm Length, Skin Fold Thickness and 5 minute Run. ④ The male group of 23yrs old showed the high values in Upper Arm Girth, Fore Arm Girth and Balance, and then female group higher in Weight, Chest Girth, Waist Girth, Upper Arm Girth, Fore Arm Girth, Thigh Girth, Power, Shuttle Run, Balance and vital capacity than any other age Groups. ⑤ In male group, Chest Girth, and Blood Pressure were significantly related, and Side Step and Trunk Extension were nagatively related to the age at 0.1% level, and then in female group, Sargent Jump, Standing Long Jump and Vital Capacity were showed a significantly related at 0.5% level. 2) The difference of physique and physical function between male and female by age. ① Everage difference in whole physique items except skinfold thickness was 9.8%, and that 21.1% in all of physical function except Trunk Flextion between male and female group subjects. ② About the ages, the 18yrs old male group showed the 22.8% higher values of 26 items, but 22yrs old male group were about 12.2% in 23 items, thus it is very lower than any other groups. 3) The difference of physique and physical function between General group and physical education group in age-matched. ① In the physique male physical education groups showed about 7% higher in Weight, Chest Girth, Upper Limb Length, Upper Arm Girth, Thigh Girth, and female group showed about 7% higher in Weight and Upper Limb Length. ② In the physical function, Trunk Flextion, 5 minute Run, and Blood Pressure(Diastolic) were about 8% high values in whole group, and female group showed about 8% higher in Standing Long Jump, Shuttle Run, and Trunk Extension. ③ In 22yrs old male and female physical education group were very dominated in physique and physical function than the other age group against the general group.

New Scaling Factors of 2-D Isotropic-Dispersion Finite Difference Time Domain (ID-FDTD) Algorithm for Lossy Media

Il-Suek Koh,Hyun Kim,Jong-Gwan Yook IEEE 2008 IEEE transactions on antennas and propagation Vol.56 No.2

<P>We modify the 2D explicit isotropic-dispersion finite-difference time-domain (ID-FDTD) scheme originally proposed for lossless media , which can drastically improve the accuracy of the 2-D ID-FDTD scheme for lossy media. The proposed scheme adopts new scaling factors for material properties such as the permittivity, permeability and conductivity. The new scaling factors can generate nearly the exact phase velocity and attenuation factor of a lossy medium for a single frequency. For the validation of the proposed scheme, two scattering problems are considered.</P>

Complete Closed-Form Expression of Dyadic Green's Function and Its Far- and Near-Field Approximations for an Impedance Half-Plane

Il-Suek Koh,Yongshik Lee IEEE 2012 IEEE transactions on antennas and propagation Vol.60 No.8

<P>A closed-form expression of the dyadic Green's function is formulated for an impedance half-plane, which is written in terms of the incomplete cylindrical function of Poisson form. Due to the branch-cut of the logarithm function that is required to calculate the input argument of the incomplete cylindrical function, the closed-form representation consists of two formulations. Since the closed-form expression contains a singularity at ρ = 0, the small argument expansion of the expression is also derived to rigorously characterize the behavior of the function at ρ ≈ 0. The previously-reported complete asymptotic expansion for the Sommerfeld integral for an impedance half-plane is not accurate for practically important cases such as near-earth propagation and/or when the surface is highly conductive. Hence, in this paper, a new complete asymptotic series of the Sommerfeld integral are derived for the case that the existing asymptotic series is not accurate. The two asymptotic series not only allow efficient numerical computation but also provide more accurate results for virtually all propagation scenarios. Based on the two asymptotic series, the complete asymptotic series of the dyadic Green's function is derived. All derived formulations are numerically verified, and their accuracies are investigated.</P>

IPO(Iterative PO)를 이용한 Ka 대역 Von Karman 레이돔 방사 특성 해석

고일석(Il-Suek Koh),박창현(Changhyun Park),선웅(Woong Sun) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.12

본 논문에서는 IPO 방법을 사용하여 Ka-band Von Karman 레이돔을 해석한다. Ka-band에서 레이돔같은 큰 물체를 해석하기 위해서는 보통의 수치 방법을 사용하기 힘들다. 그리고 PO(Physical Optics) 방법은 다중 반사(multiple reflection)를 고려할 수 없어 레이돔 해석에서 중요한 파라미터인 부엽(sidelobe level) 해석의 정확도에 한계를 갖는다. 그러므로 본 논문에서는 Nystrom 기반 PO 방법을 사용하는 IPO 방법을 사용하여 Ka-band 레이돔 해석 방법을 제안하고, 정확도 검증을 위해 Ku-band 실험 데이터와 IPO 결과를 비교한다. 또 Ka-band 시뮬레이션을 통해 높은 주파수에도 제안된 IPO 방법이 사용할 수 있음을 수치적으로 보인다. In this paper, the radiation properties of a Ka-band Von Karman radome are analyzed by using an IPO(Iterative PO) scheme. Since the operating frequency is very high, and the size of the considered radome is large, a numerical method cannot be directly applied to calculate the properties of the radome such as transmission loss, radome pattern, boresight error, etc. Hence, in this paper, an IPO scheme is used, which can efficiently consider the multiple interaction inside the radome. Also, the IPO scheme is based on the PO scheme, which is efficient and fast in a numerical point of view. The proposed scheme is verified based on Ku-band measurement data, and its feasibility for applicability to a higher frequency simulation is addressed through a simulation at the Ka-band.

Rayleigh와 Ricean 채널 환경에서 동작하는 시역전 통신 채널 용량

고일석(Il-Suek Koh) 한국통신학회 2009 韓國通信學會論文誌 Vol.34 No.3

본 논문에서는 협대혁 시 역전 통신 시스템의 이론적 ergordic 채널 용량의 수식을 closed-form으로 구한다. 시역전 통신 방식은 송신단에서 보낸 신호를 시 역전 어레이들이 받아 이를 시간 축에서 역전시켜 데이터와 함께 보내는 통신 방식이다. 본 논문에서는 송신단은 하나의 안테나로 구성되어 있고 시 역전 어레이는 여러 안테나로 구성되어 있고 안테나사이의 간격이 넓어 수신 신호는 독립적이라 가정한다. 또 채널의 변동이 충분히 느려 시역전과정 동안 채널의 변화는 없다고 가정한다. 그리고 채널 페이딩 특성을 Rayleigh와 Ricean이라 가정한다. 수치 해석을 통해 시 역전 통신 방식과 기존의 통신 방식을 비교해서 시 역전 통신의 장, 단점을 논한다. In this paper, a closed-form expression of the ergodic channel capacity for a narrow-band time-reversal comm unication scheme is analytically formulated. In the time-reversal communication scenario, a transmitter sends a si gnal and a so-called time-reversal array receives the signal. Then, the received signal is reversed in the time do main and resent to the original transmitter. Here, one transmitter and an antenna array for the time-reversal array are assumed. Since the spacing between the array elements is large, the signals received by each antenna elemen t can be considered independent. For simplicity, the communication channel is assumed stationary, whose properti es are not changed for the time-reversal process. Based on the obtained formulation, the channel capacities for th e time-reversal and the conventional channels are compared.

딥러닝 기반 교재 문항 검출 실험 연구

김태종 ( Kim Tae Jong ),한태인 ( Han Tae In ),박지수 ( Ji Su Park ) 한국정보처리학회 2021 정보처리학회논문지. 소프트웨어 및 데이터 공학 Vol.10 No.11

최근 학습, 교육 및 훈련으로 일컫는 이러닝 분야에서 교육(education)과 기술(technology)이 접목된 에듀테크(edutech)에 대한 연구가 활발하게 진행되고 있다. 그러나 디지털 기기에서 자동으로 수집이 가능한 학습활동 데이터를 기반으로 학습자 개개인에게 맞춤형 학습을 제공하는 연구는 많으나, 오프라인 학습에서 추출하고 활용해야 할 데이터의 수집 연구는 적다. 이에 본 연구는 데이터 수집 연구를 위해 인공지능 컴퓨터 비전 기술을 이용하여 교재 또는 문제지의 문항 검출 방법을 연구한다. 이는 교재 또는 문제지에 대한 디지털로의 변환작업 없이도 오프라인 학습활동 데이터를 수집·저장·분석하여 지능화 교육 서비스와 연계를 통해 오프라인 학습에서도 학습자의 개인 맞춤형 학습 서비스 제공한다. Recently, research on edutech, which combines education and technology in the e-learning field called learning, education and training, has been actively conducted, but it is still insufficient to collect and utilize data tailored to individual learners based on learning activity data that can be automatically collected from digital devices. Therefore, this study attempts to detect questions in textbooks or problem papers using artificial intelligence computer vision technology that plays the same role as human eyes. The textbook or questionnaire item detection model proposed in this study can help collect, store, and analyze offline learning activity data in connection with intelligent education services without digital conversion of textbooks or questionnaires to help learners provide personalized learning services even in offline learning.

Simple Expression of Ergodic Capacity for Rician Fading Channel

KOH, Il-Suek,HWANG, Taewon The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.6

<P>In this letter, a new exact expression of the ergodic channel capacity for a Rician fading channel is provided that is written in terms of exponential integral and incomplete gamma function. Also, a good approximation of the Rician fading channel capacity is derived from the exact expression and its accuracy is numerically verified.</P>

An Approximate Formulation for Scattering by Very Thin Dielectric Scatters

Koh, Il-Suek The Korean Institute of Electromagnetic Engineerin 2004 한국전자파학회논문지 Vol.15 No.8

본 논문에서 얇은 균질 유전체의 산란해석을 위한 근사식이 유도된다. 이 해는 volumetric integral equation을 바탕으로 Fourier transform형식으로 나타내어진다. 얇은 무한 평면구조에서는 구한 식은 정확한 해로 떨어지며 다른 2D 또는 3D 구조에 대해서는 수치해석 결과와 비교하여 구한 식의 유용성을 보였다. 특히 TM파가 edge-on 방향으로 입사할 경우 반 무한 평면 구조에서의 산란에 대한 closed-form식을 구했다. 구한 식은 넓은 범위의 유전률에 대해 정확한 결과를 예측한다. In this paper, a novel approximate solution for scattering by a very thin planar homogeneous dielectric scatterer with an arbitrary shape is formulated. This solution is based on a volumetric integral equation and is expressed in terms of Fourier transform. It is shown that the obtained solution is reduced to an exact solution for an infinite dielectric slab. For 2D, or 3D scatterers, the formulation is verified numerically. Especially fur edge-on TM polarized wave incidence a closed-form solution of backscattering from a thin dielectric half-plane is formulated, which is very accurate for wide range of normalized surface impedance except very low impedances(│η│〈0.5).

A Uniform Formulation for Scattering by Very Thin Dielectric Strips for TM Wave Incidence

Koh, Il-Suek The Korean Institute of Electromagnetic Engineerin 2004 한국전자파학회논문지 Vol.15 No.8

본 논문에서 TM 파가 입사할 때 얇은 유전체 strip의 산란특성에 대한 새로운 근사식을 구했다. 구한 식은 uniform하다. 즉 이 식은 어떠한 입사각 또는 관측점, 유전률, strip의 두께 등 모든 경우에 사용할 수 있고 다른 수치해석 방법, MoM을 이용하여 구한 식의 정확도를 여러 경우에 관해 검사해 보았다. In this paper a new approximate formulation for bistatic scattering by a thin dielectric strip for TM wave incidence is obtained. This formulation is uniform which is valid for any incident angles, observation points, and any properties of the skip such as dielectric constants, width, and thickness. The accuracy of the proposed solution is examined by comparisons with a method of moments(MoM) for various situations.

Scattering Model for Hard Target Embedded inside Forest Using Physics-based Channel Model Based on Fractal Trees

고일석,Koh Il-Suek The Korean Institute of Electromagnetic Engineerin 2005 한국전자파학회논문지 Vol.16 No.2

In this paper, a hybrid model is developed, which can estimate scattering properties of a target embedded inside a forest. The model uses a physic-based channel model for a forest to accurately calculate the penetrated field through a forest canopy. The channel model is based on a fractal tree geometry and single scattering theory. To calculate scattering from the target physical optics(PO) is used to compute an induced current on the target surface since the dimension of the target is generally very large and the shape is very complicated. Then using reciprocity theorem, scattering generated by the PO current is calculated without an extra computational complexity. 이 논문에서는 숲 속에 숨어있는 타겟의 산란 특성을 계산할 수 있는 효율적인 모델을 계발한다. 이 산란모델은 숲의 산란 특성을 계산하기 위해 프랙탈 기하학과 single scattering 이론을 사용하는 channel model과 타겟 자체의 산란 특성을 계산하기 위해 physical optic(PO) 근사법을 사용하는 hybrid 모델이다. 그리고 전체 모델의 계산량을 줄이기 위해 가역정리를 사용하여 간단하게 타겟과 숲 사이의 상호 작용을 계산한다.