• Journal of Korean Clinical Health Science
• /
• v.8 no.1
• /
• pp.1362-1368
• /
• 2020

Purpose. In this study, The change of the accommodation function due to the use of a smartphone was objectively evaluated using an Auto Refractokeratometer and was to investigate the effect of accommodation response and microfluctuations of accommodation on stable fatigue. Methods. Twenty subjects (20 males, 20 females) who had no abnormalities in ophthalmic disease and strabismus, diplopia, suppression, convergence and ocular movement, and corrected visual acuity and unaided visual acuity of 0.8 or more were performed. The average age of the participants is (21.78 ± 1.78) years old. The refractive power of the eye was measured using an Auto Refractokeratometer (Speedy-i K-model, Righton Mfg Co. Tokyo Japan), and the equivalent spherical power was automatically calculated from the measured refractive power. The accommodation response amount was calculated for the accommodation stimulation amount in 8 steps in 0.5D increments from + 0.50D to -3.00D in the calculated equivalent spherical power. The microfluctuations of accommodation in the high frequency region was calculated according to the change in the amount of the accommodation stimulus. At this time, the spectral power of the microfluctuations of accommodation was analyzed by Fast Fourier Transformation (FFT). Results. After using the smartphone, it was found that the accommodation response to accommodation stimulation decreased and the microfluctuations of accommodation increased. Conclusions. It can be said that the use of a smartphone affects the accommodation response and the microfluctuations of accommodation, thereby causing a accommodative stable fatigue. Therefore, it is thought that the use of a smartphone for a long time may bring about a change in the accommodation function.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 1999.11a
• /
• pp.233-237
• /
• 1999

Aromatherapy는 향을 이용하여 생리적 및 심리적 효과를 나타내는 치료법이다. 향의 종류에 따라 여러 효과들이 나타나고 있는데 본 연구에서는 이완 유도향 제품을 개발하기 위해 자율신경계로부터의 신호인 Galvanic skin resistance(GSR), 피부온도, 심박수 등과 뇌파에서의 변화를 측정하여 이완의 정도를 측정하고자 하였다. 실험방법은 4 종류의 aromatherapy용으로 조제된 복합향(#2033, #2026, #11, #13)을 이용하고 피검자는 후각기능이 정상이며 물리적 및 심리적 stress가 없고, 음주, 담배를 3일전까지 경험이 없는 군을 택하였다. 향을 주는 시간은 1분으로 하였으며 순서에 의한 효과를 없애기 위해 4 종류를 random order에 의해 실시하였다. 대조군으로는 증류수를 이용하여 실험 전, 실험 중, 실험 후에서 각각 측정하였으며 또한 각성효과가 좋은 jasmine과 이완 효과를 보이는 lavender를 같은 protocol로 시행하여 이완의 효과를 비교하였다. 뇌파는 FFT분석에 따라 각 주파수 영역 즉 beta, alpha, theta, delta로 나누어 분석하였다. Jasmine과 lavender의 이완 효과에서는 GSR의 변화와 HRV의 변화를 보고한 바 있다(백,1998). 또한 심리불안 효과와 향 이미지 검사를 동시에 시행하여 주관적지표로 삼았다. 실험 결과에서는 이러한 4 종류의 향은 모두 GSR의 현저한 감소 효과를 보였으며, 심박수와 피부온도의 감소경향을 나타내었다. 자율신경계 반응에 따라 4 종류 향의 이완 효과의 순서를 결정할 수 있었다. 주관적 검사와의 상관관계도 잘 나타났으며 이미지는 이완 정도와 섬세하다 항목이 잘 반영되었다. 뇌파의 변화에서는 의미 있는 변화는 보이지 않았다. 결론적으로 relaxation 효과는 GSR를 비롯한 자율신경계지표에서 잘 반영되었다.^2$=.792가 되었다. 설명되는 누적분산값은 67.18%였다.주관적 평가의 결과와 객관적 평가 결과를 이용해 마직물의 태를 평가하는 산출식을 제시하였다. 태 평가치의 경우 16가지 특성치를 모두 넣는 방법과 stepwise 방법, 또 Kawabatark 사용한 순차적 군 회귀법의 세가지 방법의 회귀식 중 16가지 특성치를 모두 넣는 방법의 결정계수가 가장 높았다.tosterone농도는 107.7$\pm$12.0 pmol／l이었고, 남성의 타액내 농도는 274.2$\pm$22.1 pmol／l이었다. 이상의 결과로 보아 본 연구에서 정립된 EIA 방법은 RIA를 대신하여 소규모의 실험실에서도 활용할 수 있을 것으로 사려된다.또한 상실기 이후 배아에서 합성되며, 발생시기에 따라 그 영향이 다르고 팽창과 부화에 관여하는 것으로 사료된다. 더욱이, 조선의 ${\ulcorner}$구성교육${\lrcorner}$이 조선총독부의 관리하에서 실행되었다는 것을, 당시의 사범학교를 중심으로 한 교육조직을 기술한 문헌에 의해 규명시켰다.nd of letter design which represents -natural objects and was popular at the time of Yukjo Dynasty, and there are some documents of that period left both in Japan and Korea. "Hyojedo" in Korea is supposed to have been influenced by the letter design. Asite- is also considered to have been "Japanese Letter Jobcheso." Therefore, the purpose of this study is to look in

• Physical Therapy Korea
• /
• v.6 no.2
• /
• pp.16-31
• /
• 1999

The purpose of this study was to assess the fatigue in lumbar and abdominal muscles in patients with chronic low back pain compared with normal subjects using spectral analysis with mean power frequency and median power frequency. The experimental group consisted of twenty subjects who had experienced chronic low back pain for over one year after the onset day. A control group consisted of twenty normal subjects with no history of low back pain. All subjects stood in an apparatus to perform sustained contraction in the lumbar and abdominal muscles for 30 seconds with 60% maximal voluntary isometric contraction (MVIC). The resulting electromyographic (EMG) recorded time serial data were transformed into frequency serial data by Fast Fourier Transformation (FFT). The results were as follows: 1) lumbar muscles measured, the frequency change ratio of both median power frequency and mean power frequency was significantly greater for experimental group compared with control group group (p<0.05). In measured two abdominal muscles (inferior rectus abdominis, obliquus externus abdominis) except superior rectus abdominis, the frequency change ratio of both median power frequency and mean power frequency was significantly greater for experimental group compared with control group (p<0.05). 2) In all three (longissimus thoracis, iliocostalis lumborum, multifidus) lumbar muscles measured, the initial frequency value of both median power frequency and mean power frequency was significantly lower for the experimental group compared with the control group (p<0.05). In the two (inferior rectus abdominis, obliquus externus abdominis) abdominal muscles measured (superior rectus abdominis not included), the initial frequency value of both median power frequency and mean power frequency was significantly lower for the experimental group compared with the control group (p<0.05). These results suggest that in patients with chronic low back pain there is a trend for more fatigue to occur in both lumbar and abdominal muscles than in the normal control group. This would seem to suggest that in treatment programs for patients with chronic low back pain, improvement of endurance in all trunk muscles should be considered.

• KIPS Transactions on Software and Data Engineering
• /
• v.7 no.3
• /
• pp.113-120
• /
• 2018

In this study, we proposed a monitoring system for identifying and handling faulty sensing stream data on manufacturing equipments where low-cost sensors can be safely used. Low cost sensors will lessen the cost of implementing distributed monitoring system, but suffer from sensor noises and inaccurate sensed data. Therefore, a distributed monitoring system with low cost sensors should identify faulty signal data as either of sensor fault or machine fault, and filter out faulty signals from sensing fault. To this end, we adopted a fourier transform based diagnostic approach mixed with a weighed moving averaging method, in order to identify faulty signals. We measured how effective our approach is and found out our approach can filter out one-third faulty signals from our experimental environment. In addition, we attached wireless communication modules to reduce sensor and network installation cost. To handle massive sensor data efficiently, we employed unstructured data format with NoSQL based database.

• Journal of Astronomy and Space Sciences
• /
• v.14 no.2
• /
• pp.275-285
• /
• 1997

We have investigated Pi 2 pulsations which were observed both on ground magnetometer array and by satellites. On November 9th in 1994, Pi 2 pulsations appeared globally on the 190/210 magnetometer chain and Hermanus station when two satellites(EXOS-D and ETS-VI) were located near the magnetic meridian of the 210 array. The local time of measurements covers from morning(LT=8.47hr) to afternoon(LT=20.3hr) and the bandwidth of peak frequency is found relatively small. The signals of the electric field are highly coherent with ground-based observations with the out of phase oscillations. However, the magnetic field measurement on the ETS-VI in the outer magnetosphere(L=6.60) shows no signature of Pi 2 pulsations over the same time interval and the correlation with any of the ground-based stations is found to be very weak, even through both satellites and magnetometer chain are located close to each other in local time. We suggest that this event may be a direct evidence of Pi 2 pulsations as virtual resonant modes which are localized in the plasmasphere(Lee 1996). The results show that the cavity mode oscillations can occur in the inner magnetosphere with less spectral noise compared to the outer magnetospheric case.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.306-307
• /
• 2011

Franz Keldysh Oscillation (FKO)은 p-n 접합 구조의 공핍층(depletion zone)에서 전기장(electric field)에 의해 발생되며, Photoreflectance (PR) spectroscopy를 통하여 관측된다. InAs/GaAs 양자점 태양전지(Quantum Dot Solar Cells, QDSCs)에서 PR 신호에 대한 Fast Fourier Transform (FFT)을 통하여 FKO 주파수들을 관측할 수 있고, 각각의 FKO 주파수들은 태양전지 구조에 대응하는 표면 및 내부전기장(internal electric field) 들로 분류할 수 있다. InAs/GaAs 양자점 태양전지에서 AlGaAs potential barrier의 두께에 따른 내부전기장의 변화를 조사하기 위해, GaAs-matrix에 8주기의 InAs 양자점 층이 삽입된 태양전지를 molecular beam epitaxy (MBE) 방법으로 성장하였다. 양자점의 크기는 2.0 monolayer (ML)이며, 각 양자점 층은 1.6 nm에서 6.0 nm의 AlGaAs potential barrier들로 분리되어 있다. 또한 양자점 층의 위치에 따라 내부전기장 변화를 조사하기 위해, p-i-n 구조에서 양자점 층이 공핍층 내에 위치한 경우와 p+-n-n+ 구조에서 양자점 층이 공핍 층으로부터 멀리 떨어진 n-base 영역에 삽입하여 실험결과를 비교분석하였다. PR 실험결과로부터, p-i-n 구조에서 InAs 양자점 태양전지의 내부전기장 변화는 potential barrier 두께에 따라 다소 복잡한 변화를 보였으며, 이는 양자점 층이 공핍층 내에 위치함으로써 격자 불일치(lattice mismatch)로 발생된 응력(strain)의 영향으로 설명할 수 있다. 이러한 결과들을 각각의 태양전지 구조에서 표면 및 내부전기장에 대해 계산된 값들에 근거하여, p+-n-n+ 구조에서 양자점 층이 공핍 층으로부터 멀리 떨어진 영역에 삽입된 경우의 결과와 비교해 보면 내부전기장의 변화는 더욱 분명해진다. 즉, 양자점 층의 potential barrier의 두께를 조절하거나, 양자점 층의 위치를 변화시킴으로써 양자점 태양전지의 내부전기장을 조작할 수 있으며, 이는 PR 실험을 통해 FKO를 관측함으로써 확인할 수 있다.

• Economic and Environmental Geology
• /
• v.18 no.4
• /
• pp.309-320
• /
• 1985

The crustal structure of the southern part of the Korean peninsula has been investigated based on the results of processing and anlaysis of gravity data. The processing techniques involve i) seperation of regional and residual anomalies by polynomial fittings, ii) power spectral analyses to determine the mean depth to the crustal base, iii) a filtering operation called "high-cut filtering and resampling," and iv) downward continuation to determine the undulation of the crustal base. The Bouguer anomalies show a lineation in the NE-SW direction which is the same as that of most mountains and tectonic lines of this area. The mean crustal depth is found to be 34km. The depth of the crustal base is varying in the estimated range of 26km to 36km with a thinner crust below the east coast than that of the west coast. The relief of the crustal base is appeared to be correlated with the regional surface topography. The linear regression relations computed between elevations and gravity anomalies indicate that the crust of this area seems to be not in perfect isostatic equilibrium but a little undercompensated state.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2002.11a
• /
• pp.233-244
• /
• 2002

The purpose of this study is to assess the ability of balance control in moving surround using head mount device and force platform and to examine the clinical usefulness of COP parameters. Fifteen patients with stroke and healthy persons were participated. COP parameters were obtained as total path distance, frequency of anterior-posterior and medial-lateral component by FFT analysis, weight-spectrum analysis in the two different conditions; (1) in comfortable standing with opened or closed eyes, (2) in virtual moving surround delivered using HMD to four different moving pattern. In virtual moving surround setting, moving pattern was composed of close-far, superior-inferior tilting(pitch), right-left tilting(roll) and horizontal rotation(yaw) movement. In all parameters, the reliebility of COP analysis system was significantly high. Also, the construct validity compared between fifteen patients with stroke and normal persons was excellent in virtual moving surround condition(p

• Physical Therapy Korea
• /
• v.8 no.2
• /
• pp.41-54
• /
• 2001

Fatigue is the decline in force produced as a result of prolonged muscle activity. Localized muscle fatigue can be identified by a shift toward low in the frequency components of the EMG signal, typically represented by a fall in the median frequency. Previous studies show that a shortened muscle develops a higher fatigue than elongated muscles. The purpose of this study was to investigate the time-related change of median frequency and torque during maximal isometric back extension exercises at different exercise angles ($0^{\circ}$, $12^{\circ}$, $36^{\circ}$, $72^{\circ}$). Twenty healthy subjects (mean age = $24.35{\pm}2.70$) were evaluated in this study. Median frequency was extracted from the EMG signals by fast Fourier transform (FFT). Initial median frequency and the slope of median frequency change over time were computed from linear regression analysis. Pearson's product moment correlation was used to quantify the relationship between slope of median frequency and torque. The results were as follows: 1) Significant differences in y-intercepts of torque regression equation with respect to exercise angle were shown. However, there were no differences in the slopes of the median frequency and torque, and y intercept of the median frequency among exercise angles. 2) There was no significant correlation between slope of median frequency and torque. 3) But there was moderate correlation between median frequency and torque at each exercise angle. In conclusion, the exercise angle during maximal isometric back extension exercise is not a direct effect on slope of median frequency and torque. But results showed that median frequency and torque shift were highly correlated in all subjects.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.12
• /
• pp.2755-2760
• /
• 2010

The moxibustion therapy of orient medical is well known. Moxibustion method is used to burning moxibustion. The variation factors of the moxibustion stimulation for body can be applied to the electronic moxibustion method. This study is to analyze and examine the electroencephalogram(EEG) variations for moxibustion stimulation. In experiment, we divided six healthy male subjects into two same sized groups : with and without stimuli. The given stimuli are the moxibustion for CV4(Kwan-Won), CV8(Shin-Guel), and CV12(Jung-wan) acupuncture points. We have analyzed the power spectrum for ${\alpha}$, ${\beta}$, ${\delta}$, ${\Theta}$ waves and the average EEG variation level and each channels variation level of EEG. The result was that the moxibustion stimulation decreased the EEG levels of parietal lobe(ch 2, 3, 6, 7) according to the somatosensory system. And the apparent different points are that mild-heat($42{\sim}44^{\circ}C$) stimulation generating ${\alpha}$-wave is increased and ${\beta}$-wave is decreased, also slight-hot($45{\sim}48^{\circ}C$) stimulation made ${\alpha}$-wave decrease and ${\beta}$-wave increase for occipital lobe(ch 4,8) on the simulation group.