• Journal of electromagnetic engineering and science
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• v.7 no.4
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• pp.201-206
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• 2007

When the M-ary signal experiences the Rayleigh fading, the diversity schemes can reduce the effects of fading since the probability that all the signals components will fade simultaneously are reduced considerably. The symbol error probabilities for various M-ary signals, such as MDPSK, MPSK and MQAM, are mathematically derived for the SC-2(Selection Combining 2) demodulation system, whereby the two signals with the two largest amplitudes are coherently combined among the L branches. On the other hand, maximum ratio combining(MRC) requires the individual signals from each path to be time-aligned, cophased, optimally weighted by their own fading amplitude, and then summed. The propagation model used in this paper is the frequency-nonselective slow Rayleigh fading channel corrupted by the Additive White Gaussian Noise(AWGN). The numerical results presented in this paper are expected to provide information for the design of radio system using M-ary modulation method for above mentioned channel environment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.886-893
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• 2000

The Characteristics of dividing the dispersed bubble, plug, and slug steam-water flow in the horizontal junctions with horizontal branches have been experimentally investigated. The experimental investigation of the separation phenomena in a $45^{\circ}$ horizontal wye with equal pipe inner diameter of 25 mm is presented to provide a data base for the development and verification of the analytical models. The phase separation and pressure distribution in the three legs of each test section are obtained through the set of measurements made in the present work. And the dependence of phase separation on different parameters, such as inlet quality and mass flux, is discussed.

• Journal of Chest Surgery
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• v.21 no.1
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• pp.184-190
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• 1988

The treatment of aortic aneurysm of ascending aorta has been fraught with difficult surgical problems. For the most part, these were resolved in 1968 with the introduction of a technique of total replacement of ascending aorta and reimplantation of the coronary arteries by Bentall and De Bono. This technique however, with all of its advantages, caries a certain problems. In chronic dissecting aneurysms, there is frequently a marked disparity in circumference between the true and false lumen distally. Distal perfusion is directed into both the true and false lumens by removing segment of the septum between the two lumens and constructing the distal graft anastomosis is to the outer layer of aortic adventitia. The distal false lumen, aortic branches and fenestrations have matured and healed in most cases. And importantly, major aortic tributaries may be solely dependent on the false lumen for perfusion. We are presenting two cases of chronic dissecting aneurysm of ascending aorta with aortic regurgitation, who have good result by surgical correction of so-called Bentall procedure with maintenance of blood flow directed into both true and false lumen.

• Journal of Applied Reliability
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• v.6 no.2
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• pp.187-194
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• 2006

In this paper, We presented the algorithm for estimating a reliability between nodes in wireless communication network such as RBN and MANET To estimate the reliability between nodes, we first modeled RNB and MANET as probability graph. Branches of the graph are always reliable and the probability of node failure is independent. After all possible simple path which can be established between two nodes are examined, we perform sharp arithmetic to remove repetition event between two nodes. Using probability for each variable of the minimized Boolean equation, we present the reliability formula.

• ALGAE
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• v.35 no.1
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• pp.33-43
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• 2020

Two species of the agar-yielding genus Gelidium, G. galapagense and G. isabelae, have previously been reported from Korea but their occurrence has not been confirmed with molecular data. We intensively collected samples of Gelidium from Jeju Island, where the two species were reported, and the southern coast of Korea. Phylogenetic analyses based on cox1 and rbcL sequences revealed that only a single species occurred in Korea. The Korean species was distantly related to G. galapagense and G. isabelae from the Galápagos Islands, and formed a clade with G. microdonticum, G. millarianum, and G. pakistanicum. A new species, G. palmatum, is described for those specimens that were previously recognized as either G. galapagense or G. isabelae from Korea. G. palmatum is small in size (up to 0.7 cm), with compressed, lanceolate axes, irregular, digitate to palmate branches, abundant rhizines in the medulla, tetrasporangial sori without sterile margins, and rounded bilocular cystocarps borne subapically on palmate branchlets.

• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.5
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• pp.209-214
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• 2021

Panoptic segmentation, which is now widely used in computer vision such as medical image analysis, and autonomous driving, helps understanding an image with holistic view. It identifies each pixel by assigning a unique class ID, and an instance ID. Specifically, it can classify 'thing' from 'stuff', and provide pixel-wise results of semantic prediction and object detection. As a result, it can solve both semantic segmentation and instance segmentation tasks through a unified single model, producing two different contexts for two segmentation tasks. Semantic segmentation task focuses on how to obtain multi-scale features from large receptive field, without losing low-level features. On the other hand, instance segmentation task focuses on how to separate 'thing' from 'stuff' and how to produce the representation of detected objects. With the advances of both segmentation techniques, several panoptic segmentation models have been proposed. Many researchers try to solve discrepancy problems between results of two segmentation branches that can be caused on the boundary of the object. In this survey paper, we will introduce the concept of panoptic segmentation, categorize the existing method into two representative methods and explain how it is operated on two methods: top-down method and bottom-up method. Then, we will analyze the performance of various methods with experimental results.

• Fisheries and Aquatic Sciences
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• v.21 no.10
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• pp.27.1-27.5
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• 2018

During a survey of marine algal flora, two gigartinalean species were collected from Pohang and Youngdeok located on the eastern coast of Korea. They share the generic morphological features of Dumontia. One is characterized by cylindrical to complanate thallus with multi- and uniaxial structure, somewhat inflated and contorted branches, and hollow medulla and cortex consisting of progressively smaller cells outwards. The other shows basically the same features as the former species but was smaller in size, as having 4-7 cm in thallus length and 1-2 mm in branch width rather than 15 and 2-5 mm. Both species are distinguished from each other only by these morphometric features. However, it is supported by molecular analysis that both species are genetically distinct. In a phylogenetic tree based on internal transcribed spacer sequence, the two species nest in the same clade as Dumontia contorta and D. alaskana, respectively. The genetic distance between both sequences within the clade was calculated as 0.0 0.2%, considered to be intra-specific for Dumontia. Based on the morphological and molecular analyses, the two Korean species are identified as D. contorta and D. alaskana described originally from Netherlands and Alaska, respectively. This is the first record of the two Dumontia species in Korea.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.150-155
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• 2018

Two siphonous green algae were collected from the eastern coast of Korea. These species share the typical features of Derbesia sporophytes, such as erect and prostrate siphonous filaments and the presence of basal septum in lateral branches. One is characterized by the combined features of a relatively small tufted sporophytic thalli arising from a rhizoidal base, subdichotomously branched filaments with a basal septum and one pyrenoid per subspherical to lenticular chloroplast. The other shows a larger sporophytic thallus, sparsely subdichotomously branched filaments with a basal septum and one pyrenoid per spherical chloroplast. In a phylogenetic tree based on rbcL sequence, the two above-mentioned Korean algae nest in the same clades as Derbesia minima and D. indica, respectively. The genetic distance between the sequences within the clades was 0.5-0.8%, which is considered to be included in the intra-specific range for the genus. These two siphonous Korean algae are identified as D. minima and D. indica, respectively, based on the morphological and molecular analyses. These species are newly recorded in the Korean marine algal flora herein.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.267-273
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• 2012

The short-range communication module was developed in this paper which is suitable for the point-to-multipoint circumstances of 40 terminals communicating frequently in about 50 meters. The media access control layer of this communication module using asynchronous time-division multiplexing provides a fast and robust performance even in the worst case of simultaneous transmission events, and low packet error rate was measured a in LOS (Line-of-sight) circumstance by adding the function of acknowledge response to media access control layer. The difference test was carried out in order to measure the performance of point-to-multipoint communication. Two communication modules are respectively measured and graphed in 10 branches to 40 branches. The communication module developed in this paper showed a faster performance than the commercial Zigbee module in the specific case presented in this paper. Especially, in over 20 branches showed wide differences of the transmission speed. This results is caused by more network overhead of Zigbee whose wider applications needs the network layer and applicaiton layer besides media access control layer. Also, the asynchronous time-division multiplexing proposed in this paper are more suitable than CSMA-CA of Zigbee module when a lot of module ought to be frequently communicated in small area.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.11-16
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• 2012

Opportunistic transmit cooperative relaying (OTR) system has been interested for its ability to mitigate the fading in wireless channel without multiple antennas in a small terminal. In OTR system, only the relays that the received Signal-to-noise ratio (SNR) from a source is greater than the threshold transmit to the destination. However, the receiving branches of a destination in a realistic system is fixed, the excess number of signals from the transmit relays does not improve the system performance and consequently increases power consumption. In this paper, we adopt Double Opportunistic Transmit (DOT) cooperative diversity system which controls the average number of transmit relays. Although the average number of the transmit relays can be controlled by adjusting the two thresholds in DOT system, the instantaneous number of transmit relays is varying in fading channel. Thus we propose Maximal Ratio Combining (MRC) or Generalized Selection Combining (GSC) according to the number of the signals from relays at the destination. The outage probability of the proposed system is derived in closed form. The analytical results show that the system performance is improved with the number of the branches. Also it is noticed that when the number of the branches is fixed, the outage probability decreases with the increase of the average SNR of S-R path and R-D path.