• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4617-4632
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• 2021

IEEE 802.11ax is a protocol being developed for high-density Wireless Local Area Networks (WLAN). Several algorithms have been proposed to improve the level of spatial reuse applied in IEEE 802.11ax. However, these algorithms are tentative and do not specify how to select the transmit power and carrier sense threshold in practice; It is unclear when and why the tuned parameters lead to better network performance. In this paper, we restricted the scale of transmit power tuning to prevent the case of backfire in which spatial reuse will result in transmission failure. If the restrictions cannot be satisfied, spatial reuse will be abandoned. This is why we named the proposed scheme as Arbitration based Spatial Reuse (ASR). We quantified the network performance after spatial reuse, and formulate a corresponding maximum problem whose solution is the optimal carrier sense threshold and transmit power. We verified our theoretical analysis by simulation and compared it with previous studies, and the results show that ASR improves the throughput up to 8.6% compared with 802.11ax. ASR can avoid failure of spatial reuse, while the spatial reuse failure rate of existing schemes can up to 36%. To use the ASR scheme in practice, we investigate the relation between the optimal carrier sense threshold and transmit power. Based on the relations got from ASR, the proposed Relation based Spatial Reuse (RSR) scheme can get a satisfactory performance by using only the interference perceived and the previously found relations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.74-74
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• 2000

This paper presents a neural network controller for a rigid-link electrically-driven robot. The proposed controller is designed in conjunction with three neural networks approximating for complicated nonlinear functions. Particularly, the fact, different from conventional schemes, is that the neural network based current observer is used. Therefore, no accurate measurement of the actuator driving current is required. In the proposed controller-observer scheme, the derived weight update rule guarantees the stability of closed-loop system in the sense of Lyapunov. The effectiveness and performance of the proposed method are demonstrated through computer simulation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.259-262
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• 2001

An improved robust hybrid control law is proposed. This law used the separated bounding function and the stiffness bound. It satisfied the performance though we don't know precise information of contact environments. It guarantees the practical stability in sense of Lyapunov. Simulation was performed to validate this law using a four-axis SCARA type robot manipulator.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.302-307
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• 1989

A pressure tracking control of hydroforming process is considered in this paper. To account for nonlinearities and uncertainties of the process, an iterative learning control scheme is proposed using Cerebellar Model Arithmatic Computer (CMAC). The experimental result shows that the proposed learning control is superior to any fixed gain controller in the sense that it enables the system to do the same work more effectively as the number of operation increases.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.161-164
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• 2000

An improved robust hybrid control law is proposed This law uses the separated bounding function: so uncertainties of each axis does not affect the others. Also, this law uses the separated $\varepsilon$, so we can take different $\varepsilon$ for each axis This law guarantees the practical stability in sense of Lyapunov. Simulation was performed to validate this law using a four-axis SCARA type robot manipulator.

• 한국융합학회논문지
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• 제9권4호
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• pp.331-339
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• 2018

본 연구는 라인댄스 수업을 통한 초등학생의 지속적 참여의사에 대한 수업몰입과 행복감에 미치는 영향을 알아보는데 목적이 있다. 연구를 위해 B광역시에 위치하고 있는 초등학교 4곳을 방문하여 271명의 자료를 수집하였다. 자료처리는 Window용 SPSS 통계 Package 22.0 Version을 이용하여 빈도분석, 탐색적 요인분석, 신뢰도 분석, 상관관계 분석 및 다중회귀분석을 실시하였다. 결과는 다음과 같다. 첫째, 몰입의 하위요인인 자기목적경험, 주의집중, 통제감, 성취감 모두 행복감 중 자신감에 대한 영향이 유의한 것으로 나타났고, 몰입의 하위요인인 자기목적경험, 통제감, 성취감이 행복감 중 자아실현감에 영향이 유의한 것으로 나타났으나 주의집중은 유의하지 않은 것으로 나타났고, 몰입의 하위요인인 자기목적경험, 주의집중, 성취감이 행복감 중 즐거움에 대한 영향이 유의한 것으로 나타났으나 통제감은 유의하지 않은 것으로 나타났다. 둘째, 몰입의 하위요인인 자기목적경험, 주의집중, 성취감은 지속적 참여의사에 대한 영향이 유의한 것으로 나타났으나 통제감은 유의하지 않은 것으로 나타났다. 셋째, 행복감의 하위요인인 자신감, 즐거움은 지속적 참여의사에 대한 영향이 유의한 것으로 나타났으나 자아 실현감은 유의하지 않은 것으로 나타났다.

• 한국전문물리치료학회지
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• 제20권3호
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• pp.45-53
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• 2013

The purpose of this study was to examine the differentiation of proprioception, invertor and evertor muscle strength, and time to peak torque at a velocity of $300^{\circ}/sec$ of the ankle joint in people with or without functional ankle instability (FAI). Nineteen subjects with a history of ankle sprain participated. All subjects were divided into FAI group ($n_1=9$, Cumberland ankle instability tool (CAIT)${\leq}24$) and a control group ($n_2=10$) based on their CAIT scores. Isokinetic dynamometer was used to measure the sense of active joint position of the ankle at mid-range and end-range of an inversion motion and invertor as well as the evertor muscle strength and time to peak torque at $300^{\circ}/s$. The FAI group showed a statistically reduction in invertor and evertor muscle strength and time to peak torque when compared to the control group (p<.05). Muscle strength and time to peak torque of the invertor and evertor, as well as the sense of active joint position at end-range were also lower in the FAI group than in the control (p<.05). Correlations between CAIT score and position sense at end-range (r=-.577) and invertor muscle strength (r=.554) were statistically significant (p<.05). Individuals with FAI showed reduction in invertor and evertor muscle strength and recruitment time as well as in proprioception of the ankle joint. Thus, proprioception and invertor and evertor muscle strength of the ankle joint at fast angular velocity may be investigated when examining and planning care for individuals with FAI.

• 한국정밀공학회지
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• 제28권5호
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• pp.638-647
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• 2011

Various approaches directly using vibrations of speakers have been suggested to effectively display the aural information such as the music to the hearing-impaired or the deaf. However, in these approaches, the human can't sense the frequency information over the maximum perceivable vibro-tactile frequency (around 1kHz). Therefore, in this study, an approach via spectral modulation of compressing the high frequency audio information into perceivable vibro-tactile frequency domain and outputting the modulated signals through the designated speakers is proposed. Then it is shown, through simulations of using Short-Time Fourier Transform (STFT) with Hanning windows and through preliminary experiments of using the vibro-tactile display testbed which is built and interfaced with a notebook PC, that the modulated signal of a natural sound composing sounds of a frog, a bird, and a water stream could produce the noise-free signal suitable enough for vibro-tactile speakers without causing Significant interfering disturbances, Lastly, for three different combinations of information provided to the subject, that is, i) with only video image, ii) with video image along with the modulated vibro-tactile stimuli as proposed in this study to the forearm of the subject, and iii) with video image along with full audio information, the effects to the human sense of reality and his emotion to given audio-video clips including various sounds and images are investigated and compared. It is shown from results of those experiments that the proposed method of providing modulated vibro-tactile stimuli along with the video images to the human has very high feasibility to transmit pseudo-aural sense to the human.

• 한국도서관정보학회지
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• 제44권3호
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• pp.125-152
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• 2013

본 연구는 근거이론 방법을 적용하여 임신부들이 경험하는 정보추구의 독특함을 총체적으로 반영한 정보추구의 실체이론을 개발하였다. 이론적 표집에 의하여 산전진료에 참여하고 있는 16명의 임신부를 대상으로 심층적인 면담을 수행하였다. 자료 분석은 근거이론 절차에 따라 자료수집과 자료 분석을 동시에 수행하였고, 지속적인 비교분석을 하였다. 임신기의 정보추구의 맥락, 구조, 과정의 분석 결과, 임신부의 정보추구 경험을 통합하는 핵심범주는 '임신에 대한 자아통제감 향상하기'로 도출하였다. 즉, 임신의 과정동안 임신부들의 의도적이고 일상적인 정보추구행위는 합맥락적이고 합리적으로 임신상황에 대처해 나갈 수 있는 능력을 향상해 나가는 과정이라는 것이다. '임신에 대한 자아통제감 향상하기'의 경험 유형은 '필사적 추구형', '적극적 추구형', '무관심 추구형', '체념적 추구형'으로 나타났다. 또한, 본 연구결과의 특징 및 선행 정보추구 모형과의 비교 및 임신부들을 위한 정보서비스 개발을 논하였다.

• 대한통합의학회지
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• 제8권4호
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• pp.265-275
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• 2020

Purpose : In this study, we would like to apply oral sensory play therapy program to children with cerebral palsy who have sensitive oral senses to find out the effect on oral sensory ability, oral function, performance ability and sociality. Methods : The subjects of this study were 20 children diagnosed with cerebral palsy, and 10 experimental groups and 10 control groups. Oral sensory play therapy programs, including oral sensory programs, were conducted in the experimental group, while only oral sensory programs were conducted in the control group. Oral Sensory Treatment Level was used to identify the sensory profile and the overall oral function of the oral function was used, and the performance and satisfaction of Canadian occupational performance measure (COPM) were examined to find out the performance of the work, and social skills were examined for social skills (SMS). Results : The level of oral sensory treatment, overall oral function, work performance and sociality all increased significantly in the experimental group, but the oral sense and oral function in the control group were significantly increased, but not significantly in the case of work performance and sociality. Conclusion : Through this study, we confirmed that oral sensory play therapy program is an effective arbitration method for oral sensation, oral function, work performance and social enhancement of children with cerebral palsy. Based on the results of this study, the study of arbitration protocols for children with cerebral palsy with oral sensory problems will have to be more active.