• Proceedings of the KSME Conference
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• 2001.06b
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• pp.313-318
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• 2001

A haptic hand controller operated by the user's hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. This paper presents a design method for KU-HHC, 6 DOF Korea University-haptic hand controller, which allows separation of workspace from linkage mechanism in consideration of the efficient user operation. First, the 3 DOF mechanism in which all the actuators are mounted on the fixed base is developed by combining a 5-bar linkage and gimbal mechanism. Then, the 6 DOF HHC is designed by connecting the two 3 DOF devices through a handle. This paper presents the forward and inverse kinematics for this device and Jacobian analysis. Improvement of the kinematic characteristics using performance index is also discussed. The hand controller KU-HHC based on this design concept and kinematic analysis was manufactured and shows excellent performance.

• ETRI Journal
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• v.38 no.1
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• pp.62-69
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• 2016

In this paper, we propose two novel user selection algorithms for multiuser multiple-input and multiple-output downlink wireless systems, in which both a base station (BS) and mobile stations (MSs) are equipped with multiple antennas. Linear transmit beamforming at the BS and receive combining at the MSs are used to avoid interference between users and find a better sum-rate capacity performance. An optimal technique for selecting users would entail an exhaustive search, which in practice becomes computationally complex for a realistic number of users. Suboptimal algorithms with low complexity are proposed for a coordinated beamforming scheme. Simulation results show that the performance of the proposed algorithms is better than that provided by previous algorithms and is very close to an optimal approach with reduced complexity.

• Journal of Broadcast Engineering
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• v.22 no.5
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• pp.570-577
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• 2017

Recently, with the development of broadcasting communication, users expect to receive high quality and various broadcasting services anytime, anywhere. In the case of terrestrial broadcasting, HD broadcasting and mobile broadcasting are provided at different frequencies. In the case of terrestrial UHD, which recently started trial broadcasting, 700MHz frequency is used which is different from the existing one. If the contents of the same contents are transmitted at different frequencies, it can be considered ineffective in terms of the use efficiency of the terrestrial broadcast frequency. As a method to solve this problem, a transmission system model and a service have been proposed for transmitting the hierarchical encoded UHD contents by SHVC on the basis of the multimedia transmission technology MMT in a heterogeneous network environment combining broadcast network and communication network. However, it is still in the initial stage of study the receiving model that can reliably receive various quality UHD contents in various environments such as mobile and fixed environment. Therefore, in this paper, we propose a receive buffer model that can reliably receive UHD contents layered on SHVC based on MMT.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.835-842
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• 2004

In this paper, we have analyzed the MC-DS/CDMA system with input signal synchronized completely through adjustment of the gain in the PLL loop, by using the hybrid SC/MRC-(2/3) technique, which is said to one of the optimal diversity techniques under the multi-path fading environment, assuming that phase error is defined to the phase difference between the received signal from the multi-path and the reference signal in the PLL of the receiver. Also, assuming that the regarded radio channel model for the mobile communication is subject to the Nakagami-m fading channel, we have developed the expressions and performed the simulation under the consideration of various factor, in the MC/DS-CDMA system with the hybrid SC.MRC-(2/3) diversity method, such as the Nakagami fading index(m), $the\;number\;of\;paths\;(L_p),$ the number of hybrid SC.MRC-(2/3) $diversity\;branches\;(L,\;L_c),$ the number of users (K), the number of subcarriers (U), and the gain in the PLL loop. As a result of the simulation, it has been confirmed that the performance improvement of the system can be achieved by adjusting properly the PLL loop in order for the MC/DS-CDMA system with the hybrid SC/MRC-(2/3) diversity method to receive a fully synchronized signal. And the value of the gain in the PLL loop should exceed 7dB in order for the system to receive the signal with prefect synchronization, even though there might be a slight difference according to the values of the fading index and the spread processing gain of the subcarrier.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.95-103
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• 2009

In this paper, a generation method of transmit and receive beamforming vectors based on base station cooperation is proposed which maximizes the user SINR in mobile cellular multi-user MIMO systems. There are two main sources of interference which deteriorate the performance of the system, i.e. the inter-user interference caused by the usage of the same radio resource for multiple users in the system, and the inter-cluster interference from neighboring base stations which are not participating in cooperative transmission. The proposed scheme cancels out the inter-user interference by using the block diagonalization(BD) method, and mitigate the inter-cluster interference by using optimal transmit and receive beamforming vectors based on optimal combining(OC) with the statistic information of inter-cluster interference. We perform computer simulations to verify the performance of the proposed scheme, and compare the result to the conventional performance obtained from utilizing the receiver side information only or utilizing the information from neither sides. The performance evaluations are conducted not only over the independent MIMO channels, but over correlated MIMO channels to demonstrate the robustness of the proposed scheme over the channels with correlation among antennas.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1519-1525
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• 2006

This paper proposes the U-healtcare middleware that is based on mininumCORBA. Ubiquitous healthcare system is generated by combining the technologies of computer system and medical system. This makes available that the person can receive medical treatment anywhere, anytime at on-line. The Healthcare devices are connected to network system as wire or wireless internet. So, the computer system can gather the vital information from the person at the real time and transfers the information to the server system that processes the medical information. When a medical doctor makes a diagnosis they can get more information about the patient by using the information within the server. Users would like to receive more services in the ubiquitous healthcare system than the traditional medical system. And in U-healthcare system, every healthcare devices and the users have to be connected to network system and the information from them has to be integrated. U-Home Healthcare middleware I proposed in this paper will do everything that I mentioned above.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.949-956
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• 2016

By recent development of wired and wireless communication technology, any service can be delivered through broadcasting networks or communication networks. So contents consumers want to receive broadcasting program via any accessible network. Network independent broadcasting system can receive optimized multimedia contents by combining the high-quality multimedia contents transmitted through broadcasting network and the additional contents delivered through communication network. Additional contents can be other multimedia contents, URL of contents, some texts for indicating information of received multimedia, etc. Network independent broadcasting system is in early stage of development, and receivers and the monitoring system for hybrid broadcast are under development. Thus the multiplexing method and demultiplexing method to perform hybrid broadcasting is on study. In this paper, we designed the demultiplexing algorithm to perform hybrid broadcasting system and implemented demultiplexer system based on modulator interface system standard T2-MI of DVB-T2.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1037-1040
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• 2005

In this paper, we analyze the performance of high data rate wireless personal area network (HDR-WPAN) system using multiple antenna scheme, space-time block code in fading channel. Multiple antenna technique is used to improve the error performance by combining the receive signal through multiple receive antenna. Space-time block code is a space-time diversity scheme which can obtain the maximum space diversity gain and easily implements a ML receiver via a simple process. HDR-WPAN system using space-time block code obtain about 14dB diversity gaint at BER 10$^{-5}$ in multipath fading channel. From the simulation result, We confirm that HDR-WPAN system adopting space-time block code has reliable communication even low power.

• Journal of Biomedical Engineering Research
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• v.19 no.2
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• pp.129-132
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• 1998

A new one-channel phased-array quadrature RF coil is developed for spine MR imaging. Quadrature RF coils for MRI have been used to improve the signal-to-noise ratio (SNR) by$"\squt{2}"$ using two orthogonal RF coils in combination. More recently, the phased-array RF coil has been proposed for more improvement of SNR by using an array of reduced-size RF coil elements. Two schemes proposed for the new phased-array quadrature RF coil are:(1) Proper overlapping of two quadrature RF coils thus removing the mutual inductance and (2) Attaching preamplifiers right after the coil section and combining the signal with proper phase delays. The coil has been implemented for receive-only mode, and tested by phantom and volunteer imaging. The experimental results show the utility of the proposed RF coil.d RF coil.

• Journal of Acupuncture Research
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• v.41 no.2
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• pp.107-114
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• 2024

Background: Low back pain (LBP) is a common musculoskeletal disorder worldwide, with a lifetime prevalence of up to 80%. Among nonsurgical treatments for chronic LBP, Korean medicine treatments are highly preferred, and pharmacopuncture therapy combining acupuncture and herbal medicine is widely used. However, no evidence-based study has focused on the use of various types of pharmacopuncture. Methods: The pragmatic randomized controlled clinical trial will include 44 participants; recruitment will start in July 2023. All participants will receive integrated Korean medicine treatment including acupuncture, cupping, and infrared therapy, and the intervention group will also receive pharmacopuncture. After 16 treatment sessions, twice a week for 8 weeks, follow-up assessments will be performed at week 9. As a pragmatic randomized controlled clinical protocol, the type, dose, and acupoints of acupuncture and pharmacopuncture are not determined in advance but are selected and recorded according to the clinical judgment of the Korean medicine doctor. Results: The primary outcome will be measured using a visual analog scale score, and the secondary outcomes include the Oswestry disability index, patient global impression of change, no worse than mild pain, and range of motion. Safety will be assessed by examining participants' self-reported adverse events and vital signs and conducting blood tests before and after the test. Conclusion: This study aims to provide clinical evidence of the effectiveness and safety of pharmacopuncture for chronic LBP.