• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.678-684
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• 2018

In order to broaden the indication of middle ear implant, research has been actively conducted on the reverse output method that stimulates the round window. However, it is very difficult to transmit the vibration output effectively because the indivisual anatomical difference of the round window niche is very large and also the visual field is not secured even by a skilled otolaryngologic surgeon. In this paper, we propose a new reverse stimulation method of middle ear implants that transmits energy to the inner ear by using air as a medium. This can compensate for the disadvantages of the conventional method of transmitting vibration energy and minimizes the energy transfer efficiency interference due to the combination of the excitation point and the output device. It was shown that forward and backward transfer characteristics were obtained by cadaveric experiments, and it was shown that it can overcome the acoustical impedance of high round window and transmit energy to inner ear. The receiver, which is the output device of the conventional hearing aids, can generate a constant volume velocity, so it can have a high output at a limited volume, such as a round window niche. So, suggested method can overcome the high acoustical impedance of the round window and deliver acoustic energy to the inner ear.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1976.06a
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• pp.87.1-87
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• 1976

Bekesy measured the sound transformation system of the middle ear 49 years ago. According to his reports, a ratio between the size of ear drum and the size of oval window is 17 : 1, and the lever function of the ossicles is physiologically 1.3 : 1. Therefore, the hearing might be aggravated to 27.5㏈ in the case of the vanishment of 3 ossicles. In 1952, Wullstein reported 5 types of tympanop-lasty and the fourth type among them was especially named for the sound-protection. The oval window is only exposed by the sound pressure and the round window is not exposed. According to the application by this idea, the post-operative hearing might be improved until 27.5㏈. Mean while, in 1942, Onchi verified through his experiment that the results of Bekesy's measurement was not completely conformed to Onchi result. Bekesy measured the sound pressure on the stapes plate of the oval window, on the other hand, Onchi measured the sound pressure on the surface of the perilymph of the oval window after removing the stapes plate(Fig. 1).(Figure omitted) The difference of their experiment is recognized that the impedance of the stapes plate exists or not (Fig. 1). Both Audiogrums are compared as Fig. 2. The result of IV type of tympanoplasty is success ful in 54% as the Table 1. (Table Omitted) The reason of unsatisfactory is caused by the thick and unmovable window-membrane and by the closing of air passage to the round window. The closing of the air passage to the round window is occurred by the adhesion between the grafting membrane and the surface of promontorium. In order to preserve this adhesion, I produce to transplantate the mucous membrane of the lip to the bone surface of tympanic cavity after removing the granulation tissue of the tympanic cavity and to form a membranous canal for the sake of air passage (Fig. 3). (Figure Omitted) The post-operative hearing by this method is shown as Fig. 4, 5. In other words, the post-operative sound pressure entered into the cochlea directly, by way of the oval window only, not by way of the round window, as a theorie of the sound protection. (Figure omitted)

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.113-119
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• 2004

Exponentiation is widely used in practical applications related with cryptography, and as the discrete log is easily solved in case of a low exponent n, a large exponent n is needed for a more secure system. However. since the time complexity for exponentiation algorithm increases in proportion to the n figure, the development of an exponentiation algorithm that can quickly process the results is becoming a crucial problem. In this paper, we propose a parallel exponentiation algorithm which can reduce the number of rounds with a fixed number of processors, where the field elements are in GF($2^m$), and also analyzed the round bound of the proposed algorithm. The proposed method uses window method which divides the exponent in a particular bit length and make idle processors in window value computation phase to multiply some terms of windows where the values are already computed. By this way. the proposed method has improved round bound.

• Journal of Information Processing Systems
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• v.2 no.1
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• pp.34-38
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• 2006

In the wireless network, TCP performs poorly because it was originally designed for wired networks and does not take into consideration wireless characteristics such as mobility, high-loss probability, and hidden-terminal problems. In particular, in the wireless multi-hop networks, a large congestion window increases the probability of contention and packet losses, and TCP performance is degraded severely as a result. So, it is necessary to limit the TCP congestion window size in order keep the probability of contention loss in the system to a minimum. In this paper, we propose a new scheme for determining the maximum congestion window size based on the measured bandwidth and Round-Trip-Time (RTT). Using ns-2 simulation, we show that the proposed scheme reduces the probability of packet contention and improves TCP performance.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.189-199
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• 2016

Many implantable hearing aids are being developed as alternatives to conventional hearing aids which has inconveniences for use and social stigma that make hearing-impaired people avoid to wear it. Particularly, the fully-implantable middle ear hearing devices (F-IMEHD) are being actively studied for mixed or sensorineural hearing impaired people. In development of F-IMEHD, the most difficult problem is improving the performance of implantable microphone. Recently, Cho et al. have studied the tympanic membrane installed microphone which has better sensitivity and is easier to operate on patient than the microphone implanted under the skin. But, it may cause howling problem due to the feedback signal via oval window and ossicle chain from the transducer on round window in the middle ear cavity, therefore, a feedback canceller is necessary. In this paper, we designed NLMS (normalized least mean square) adaptive feedback canceller for F-IMEHD with tympanic membrane installed microphone and a transducer implemented at round window, and computer simulation was performed to verify its operation. The designed adaptive feedback canceller has a delay filter, a 64 point FIR fixed filter and a 8-tap adaptive FIR filter. Computer simulation of the feedback path is modeled by using the data obtained through human cadaver experiment.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.330-341
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• 2007

This work analyzes the performance of the parallel packet switch (PPS) with a sliding window (SW) method. The PPS involves numerous packet switches that operate independently and in parallel. The conventional PPS dispatch algorithm adopts a round robin (RR) method. The class of PPS is characterized by deployment of parallel low-speed switches whose all memory buffers run more slowly than the external line rate. In this work, a novel SW packet switching method for PPS, called SW-PPS, is proposed. The SW-PPS employs memory space more effectively than the existing PPS using RR algorithm. Under identical Bernoulli and bursty data traffic, the SW-PPS provided significantly improved performance when compared to PPS with RR method. Moreover, this investigation presents a novel mathematical analytical model to evaluate the performance of the PPS using RR and SW method. Under various operating conditions, our proposed model and analysis successfully exhibit these performance characteristics including throughput, cell delay, and cell drop rate.

• 대한공업교육학회지
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• v.32 no.2
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• pp.199-216
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• 2007

Stream Control Transmission Protocol(SCTP) is a transport layer protocol to support the data transmission. SCTP is similar to Transmission Control Protocol(TCP) in a variety of aspects. However, several features of SCTP including multi-homing and multi-streaming incur the performance difference from TCP. This paper highlights the data transfer during the initial slow start phase in SCTP congestion control composed of slow start phase and congestion avoidance phase. In order to compare the mean transfer time between SCTP and TCP, we experiment with different performance parameters including bandwidth, round trip time, and data length. By varying data length, we also measure the corresponding initial window size, which is one of factors affecting the mean transfer time. For the experiment, we have written server and client applications by C language using SCTP socket API and have measured the transfer time by ethereal program. We transferred data between client and server using round-robin method. Analysis of these experimental results from the testbed implementation shows that larger initial window size of SCTP than that of TCP brings the reduction in the mean transfer time of SCTP compared with TCP by 15 % on average during the initial slow start phase.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.91-100
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• 2004

This paper presents a receiver-driven TCP flow control mechanism, which is adaptive to the wireless condition, for memory constrained mobile receiver. A receiver-driven TCP flow control is, in general, achieved by adjusting the size of advertised window at the receiver. The proposed method constantly measures at the receiver both the available wireless bandwidth and the packet round-trip time. Depending on the measured values, the receiver adjusts appropriately the size of advertised window. Constrained by the adjusted window which reflects the current state of the wireless network, the sender achieves an improved TCP throughput as well as the reduced round-trip packet delay. Its implementation only affects the protocol stack at the receiver and hence neither the sender nor the router are required to be modified. The mechanism has been implemented in real environments. The experimental results show that in CDMA2000 1x networks the TCP throughput of the proposed method has improved about 5 times over the conventional method when the receiver's buffer size is limited to 2896 bytes. Also, with 64Kbytes of buffer site, the packet round-trip time of the proposed method has been reduced in half, compared the case with the conventional method.

• Journal of Biomedical Engineering Research
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• v.39 no.5
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• pp.183-187
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• 2018

In this paper, we investigated the efficiency according to the output transmission method of the round window driving type AMEIs (active middle ear implants) through the cadaveric experiment. For the experiment, we fabricated DRT (direct rod transducer) and FMT (floating mass transducer) type vibrational transducers based on our previous studies and conducted their output characteristics were measured. TCBT (tri-coil bellows transducer) and DFMT (differential floating mass transducer) were implemented with the same driving force and electrical characteristics as one of DRT and FMT, respectively. In the experiment using three human temporal bone, normal stapes vibration was measured with 1 Pa in front of tympanic membrane, and then was compared with each output of transducers. From the comparison, the DRT type vibration transducer was superior in overall energy transfer efficiency, especially in the low frequency range. There was no difference in implantation difficulty between the two transducers. The results of this study suggest that the DRT type vibrational transducer is more efficient and needs further study to overcome the low frequency degradation in round window approaching with FMT.

• Korean Journal of Agricultural Science
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• v.39 no.2
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• pp.271-277
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• 2012

Dimensions, operation conditions and improvement items for round roof windows were investigated in arch shape single-span plastic greenhouse with roof vents, and natural ventilation performance was analyzed based on the ventilation theory. Diameter of round roof windows was mostly 60 cm, and chimney height projected on roof was average 30 cm. Installation space was mostly 5 to 6 m but farmhouse of 10 m and over was 16.7% also. A round roof window which has 60 cm diameter was installed to 6 m space generally and 80 cm diameter was installed to 10 m space, but correct standards did not exist. There were a lot of opinions that ventilation effect of round roof windows is fairly good and user satisfaction is generally excellent. It is problem that there is few effects in summer and that vinyl around each vent tears well and rainwater leaks, and improvement hope item required development of automatic control system. In the wind speed of 0.3 m/s, it was estimated that natural ventilation rates were 0.69, 0.55, 0.50 and 0.48 volumes per minute in case of 2, 4, 6 and 8 m installation space for round roof windows, respectively. It was analyzed that the ratio of ventilation due to buoyancy out of total ventilation were 65.2, 41.9, 29.9 and 22.8% in case of 2, 4, 6 and 8m installation space, respectively. By the round roof windows installed at space of 6 m, ventilation rate was estimated to 0.5 volumes per minute, and we can expect the increase in ventilation rate of 30%. In order to meet the recommended ventilation rate for summer season, we have to install the round roof windows at space of 1 to 2 m. However, it is difficult to apply those installation space because of falling productivity due to lower light transmittance as well as rising costs. It is estimated that the installation space of 6m is appropriate for spring or fall season. Therefore it is necessary to encourage installing the roof windows in single-span plastic greenhouses.