• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.230-233
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• 2003

In this paper, it is shown that, in DS/CDMA mobile systems, halving or doubling the spreading factor (HSF or DSE) when retransmission is requested possibly improves the throughput. Given transmit power, DSF essentially decreases probability of packet error (PPE) by increasing the signal energy per information bit. It, however, doubles the time duration needed for transmitting the original packet. On the other hand, HSF increases PPE. It, however halves the time duration required to carry the original packet. Thus, the efficiency of HSF or DSF as a retransmission strategy depends on the amount of increased or reduced PPE after HSF or DSF is selected. With achieving given residual error probability (REP) in CDMA systems, the effective throughput is evaluated in this paper to find conditions with which HSF or DSF achieves better performance than using the original one. Analytic results show that HSF or DSF performs better when relatively small or big changes in their PPE's are present, respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.6
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• pp.563-567
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• 2001

We generalize the widebane P0-weyl symbol (P0WS) and the widebane spreading function (WSF) using the generalized warping function . The new generalized P0WS and WSF are useful for analyzing system and communication channels producing generalized time shifts. We also investigated the relationship between the affine Wey1 symbol(AWS) and the P0WS. By using specific warping functions, we derive new P0WS and WSF as analysis tools for systems and communication channels with non-linear group delary characteristics. The new P0WS preserves specific types of changes imposed on random processes. The new WSF provides a new interpretation of output of system and communication channel as weighted superpositions of non-linear time shifts on the input. It is compared to the conventional method obtaining output of system and communication channel as a convention integration of the input with the impulse response of the system and the communication channel. The convolution integration can be interpreted as weighted superpositions of liner time shifts on the input where the weight is the impulse response of the system and the communication channel. Application examples in analysis and detection demonstrate the advantages of our new results.

• Journal of the Korean Wood Science and Technology
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• v.17 no.2
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• pp.20-25
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• 1989

This study was carried out in order to investigate the treatment effect of PEG soln which is a common dimensional stabilizer to green log. sawing panel etc, on bonding product including plywood widely-used in secondary processing unit. The 30% concentration of aqueous PEG soln. with molecular weight of 400, 1.000 and 4,000 were prepared respectively, and also dipping the veneer in the PEG soln. spreading the PEG soln. on veneer and mixing the PEG soln. in the adhesive were allowed. Then the ratio of PEG impregnation on veneer, the adhesive strength of plywood were epitomized as follows: The ratio of impregnation by PEG 4,000 at dipping condition was highest. while that by PEG 400 at same condition was lowest. However, the effect of PEG molecular weight on the ratio of impregnation at spreading condition did not occur. 2. The adhesive strength was great in the order of 4,000>400>1,000 in molecular weight of PEG at dipping and spreading conditions. In case of mixing the PEG soln. in the adhesive, the adhesive strength was great in the order of 400>1,000>4,000 in molecular weight of PEG. Throughout three treatment conditions, PEG 400 was relatively favourable with about 10kg/$cm^2$ dry strength. 3. The adhesive strength was great 10 the order of spreading >dipping >mixing condition. 4. Although adhesive strength with the 30% concentration of aqueous PEG soln. was decreased by 35% and over, compared to control (non-treatment) adhesive strength, all types of PEG treatment except mixing the PEG soln. in the adhesive exceeded the standard dry strength for common use panel. 7.5kg/$cm^2$. 5. In warm water-proof test, the adhesive strengths by all PEG treatment conditions were less than the standard wet strength, 7.5kg cot, and also delamination of glue line occured mostly in mixing in the PEG soln. in the adhesive condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.11
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• pp.969-975
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• 2002

Thin film transistors(TFT) were made based on the polycrystalline Si (poly-Si) crystallized by sequential lateral solidification(SLS) method. The electrical characteristics of the devices were analyzed. n-type TFTs did not show a superior characteristics compared to p-type TFTs. We analyzed the causes of the failure by focused ion beam(FIB) analysis and automatic spreading resistance(ASR) measurement, to study the structural integrity and the doping distribution, respectively. FIB showed no structural problems but it revealed a non-intermixed layer in the contact holes between the polysilicon and the aluminum electrode. ASR analyses on poly-Si layer with various doping concentrations and activation temperatures showed that the inadequately doped areas were partially responsible for the inferior behavior of the whole device.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.1
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• pp.13-18
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• 2019

This paper analyzes the signal acquisition performance of the legacy GNSS spreading codes and a polyphase code. The code length and chip rate of a polyphase code are assumed to be same as those of the GPS L1 C/A and Galileo E1C codes. The autocorrelation and cross correlation characteristics are analyzed. In addition, a way to calculate a more accurate probability of false alarm for a code with sidelobe non-zero auto-correlation function is proposed. Finally, we estimate the probability of detection and the mean acquisition time for a given signal strength and the probability of false alarm.

• Journal of the Korean earth science society
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• v.44 no.6
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• pp.643-654
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• 2023

The West Philippine Basin, an oceanic basin half the size of the Philippine Sea Plate, lies in the western part of the plate and south of the Korean Peninsula on the Eurasian Plate. It subducts beneath the Eurasian Plate and the Philippine Islands bordering the Ryukyu Trench and the Philippine Trench with 25-50% of this basin already consumed. However, the history of the opening of the basin's southern region has been a topic of debate. The non-transform discontinuity formed during the seafloor spreading is similar to the transform fault boundaries normally perpendicular to mid-ocean ridge axes; however, it was created irregularly due to ridge propagations caused by variations of mantle convection attributable to magma supply changes. By analyzing high-resolution multi-beam echo-sounding data, we confirmed that the non-transform discontinuity due to the propagating rift evolved in the entire basin and that the abyssal hill strike direction changed from E-W to NNW-SSE from the fossil spreading center. In the early stage of basin extension, the Amami-Sankaku Basin was rotated 90 degrees clockwise from its current orientation, and it bordered the Palau Basin along the Mindanao Fracture Zone. The Amami-Sankaku Basin separated from the Palau Basin while the spreading of the West Philippine Basin began with a counter-clockwise rotation. This indicates that the non-transform discontinuities formed by a sudden change in magma supply due to the drift of the Philippine Sea Plate and simultaneously with the rapid changes in the spreading direction from ENE-WSW to N-S. The Palau Basin was considered to be the sub-south of the West Philippine Basin, but recent studies have shown that it extends into an independent system. Evidence from sediment layers and crustal thickness hints at the possibility of its existence before the West Philippine Basin opened, although its evolution continues to be debated. We performed a combined analysis using high-resolution multi-beam bathymetry and satellite gravity data to uncover new insights into the evolution of the West Philippine Basin. This information illuminates the complex plate interactions and provides a crucial contribution toward understanding the opening history of the basin and the Philippine Sea Plate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.400-403
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• 2004

A non-heat기leafed steel does not need quenching and tempering processes that are called a heat treatment differently from conventional steel. Since the tensile strength of this steel is higher than 900MPa, a conventional forming process should be changed to incremental forming process such as a cross wedge rolling that requires lower load capacity than conventional ones. In this paper, the cold cross wedge rolling (CWR) die has been designed using CAD/CAE In order to produce near-net-shaped component of ball stud of non-heat-treated cold steel. Finite element analyses were applied in order to investigate process parameters of CWR. Results provide that the stretching angle and the forming angie at knifing zone in CWR process is important parameter to be the stable process under the low friction coefficient condition.

• Korean Journal of Cognitive Science
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• v.16 no.1
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• pp.17-27
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• 2005

After prolonged viewing of a moving pattern, a stationary pattern can appear to move in the opposite direction, a phenomenon known as motion aftereffect (MAE). Unlike the classical explanation MAE was not confined to an adapted region; instead it can spread to an adjacent region, which was not adapted previously. In order to examine the relative locus of the mechanism responsible for MAE spreading, a rotating harmonic spiral pattern was presented as an adapting stimulus within an annulus window, and then the duration of MAE was measured in both the adapted annulus region and the non-adapted inner region. Two different kinds of test patterns were used: the same and mirror images of the original adapting pattern. An interesting characteristic of a harmonic spiral is that the orientation of a contour at a given location is different from thar of its mirror image by 90 degrees, and consequently the adapting effect of local motion detector is not expected to occur in the mirror image. The results showed that MAE duration in an adapted region was longer in the same image condition than in its mirror image condition, while MAE duration in an non-adapted region was not found to be different between those two different image conditions. These results suggest that MAE spreading might be produced by the adaptation of global motion detectors, not by local motion detectors.

• Journal of Korean Association for Spatial Structures
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• v.19 no.4
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• pp.77-84
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• 2019

This study introduces a newly developed PC non-bearing wall system to prevent the damage of RC wall-type apartments that have been heavily damaged by the 2017 Pohang Earthquake. In order to evaluate the performance of the developed PC non-bearing wall system, a static cyclic test is conducted. The prototype of test specimen is from the RC wall-type apartment which has been severely damaged by the 2017 Pohang Earthquake. The specimen with the conventional non-bearing wall system showed the similar damage of RC wall type apartment suffered from the Pohang Earthquake. In case of the specimen with the developed PC non-bearing wall system, cracks and damages were not transmitted between the walls due to the seismic slit and there were almost no cracks in the non-bearing walls. Therefore, the proposed non-bearing wall system, separated from the structural walls, could prevent spreading cracks to bearing walls and make it possible to effectively control damage due to earthquake loads.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.44-50
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• 2014

Chaos communication system is one of the security algorithms that is applied to improve the security. Chaos signal is non-linear, and it is generated randomly according to the initial conditions. Also, chaos communication system has characteristics such as non-periodic, wide-band, non-predictability of signals and easy implementation. So, security of chaos communication system is superior, and it has low interception probability and good anti-jamming characteristic. However, BER performance is worse than digital communication system, because it has many self interference signal in case of CDSK system. To improve these disadvantages, we analyze the PDF trend which can improve the BER performance in existing study, and we proposed a chaos map. And, proposed chaos map was defined as the 'Boss map'. Generally, BER performance is changed according to initial values, parameters and spreading factors. Therefore, in this paper, we will introduce PDF trends which can improve the BER performance, and will describe about Boss map. Also, characteristics of Boss map is analyzed by evaluating the BER performance of Boss map according to initial values, parameters and spreading factors. As a result, while maintaining the similar BER performance, initial value of Boss map can be selected from 0 to 1.2, and BER performance is best when parameter alpha is 2.5. Also, BER performance is best when spreading factor is 50.