• Ocean Systems Engineering
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• v.6 no.2
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• pp.143-159
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• 2016

Cargo, such as a Tension Leg Platform (TLP), Semi-submersible platform (Semi), Spar or a circular Floating Production Storage and Offloading (FPSO), are frequently dry-transported on a Heavy Lift Vessel (HLV) from the point of construction to the point of installation. The voyage can span months and the overhanging portions of the hull can be subject to frequent wave slamming events in rough weather. Tie-downs or sea-fastening are usually provided to ensure the safety of the cargo during the voyage and to keep the extreme responses of the cargo, primarily for the installed equipment and facilities, within the design limits. The proper design of the tie-down is dependent on the accurate prediction of the wave slamming loads the cargo will experience during the voyage. This is a difficult task and model testing is a widely accepted and adopted method to obtain reliable sea-fastening loads and extreme accelerations. However, it is crucial to realize the difference in the inherent stiffness of the instrument that is used to measure the tri-axial sea fastening loads and the prototype design of the tie-downs. It is practically not possible to scale the tri-axial load measuring instrument stiffness to reflect the real tie-down stiffness during tests. A correlation method is required to systematically and consistently account for the stiffness differences and correct the measured results. Direct application of the measured load tends to be conservative and lead to over-design that can reflect on the overall cost and schedule of the project. The objective here is to employ the established correlation method to provide proper high-frequency responses to topsides and hull design teams. In addition, guidance for optimizing tie-down design to avoid damage to the installed equipment, facilities and structural members can be provided.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.3
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• pp.9-18
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• 1985

The numerical calculation for solving boundary-value problem related to potential flows with a free surface is carried out by application of the localized finite element method. Only forced motion of 2-D body in infinitely deep fluid is considered, although this schemes is equally applicable to any first order time-harmonic problems of similar nature. The infinite domain of the fluid is separated into the inner flow field and the outer flow field with common inter-surface boundary. The finite element method is applied to obtain the solution in the inner flow field and the Green functions are utilized to represent the solution in the outer flow field. At the inter-surface boundary, the continuity of the value of potential and the normal derivative of the potential(i.e. matching condition) is conserved. The present method has better computational efficiency than the previous LFEM and the integral equation method of Frank. This enhanced computational efficiency is presumably due to the fact that the present method gives a symmetric coefficient matrix and requires less computational time in calculating the influence coefficient matrix of Green function than the integral equation method. And the irregular frequency desen't exist because the uniqueness of the solution is assured by the such that the exact free surface condition is satisfied on the boundary of the localized finite element region(i.e. inner region). As an example of the above method, the hydrodynamic forces for the circular cylinder and the rectangular cylinders are calculated. In the computed results, the small number of singularity distribution segments($3{\sim}6$) give good result relative to Ursell's and Vugts'.

• Journal of the Korea Computer Graphics Society
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• v.7 no.2
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• pp.29-35
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• 2001

In general, image-based virtual environment is represented by panoramic images created by image mosaic algorithm. The cylindrical panoramic image supports the fixed-viewpoint navigation due to the constraints of construction. Shum proposed concentric mosaics to allow users to navigate freely within a circular area[10]. It is constructed by a sequence of images which is acquired from a regularly rotating camera. Concentric mosaics technique, proposed by Shum, is considered as 3D plenoptic function which is defined three parameters : distance, height and angle. In this paper, we suggest an effective method for creating concentric mosaics, in which we first align a set of strip images on the cylinder plane and stitch the aligned strips to build a panoramic image. The proposed method has no constraints such as regular panning motion of camera. Furthermore, our proposed method minimizes the use of interpolation image to create a novel view images from the concentric mosaics. It allows the result image on a novel view to have better quality with respect to the number of input images.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.66-78
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• 2002

In this paper, we propose a new symbol offset estimation technique for an orthogonal frequency-division multiplexing (OFDM)-based wireless LAN. When both inter-symbol interference (ISI) and inter-channel interference (ICI) do not exist in an OFDM symbol, symbol offsets cause circular shifts in the estimated channel impulse response (CIR) by the amount of symbol offset. Also, the power delay profile of a typical multipath wireless channel can be modeled by exponentially decaying function, and most energy of multipath channel is concentrated at the beginning part of the CIR. Based on these properties, the proposed symbol offset estimation technique estimates the CIR, which is circularly shifted by the amount of symbol offset, and then calculates the partial mean power from the estimated impulse response by using a moving window with a finite length. And, symbol offset can be estimated from the index of a moving window having the maximal partial mean power. The proposed technique can reduce noise effect in the process of the CIR estimation, and remove ISI and ICI using repetitive training symbol structure in time-domain for minimum training overhead. The performances of the proposed symbol offset estimation technique in typical indoor channels are demonstrated by computer simulation.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.2
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• pp.69-74
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• 2003

The purpose of this study was to obtain the color change information for natural tooth of all age groups. Fifty Korean subjects(25 men and 25 women) were randomly selected for this study. They were ranged in age from 24 to 67 years old and were classified into 5 age groups for each sex: 20 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 69 years. Maxillary central incisor of each subject free from obvious discoloration and restorations on the sites to be measured was selected. Three sites on the labial surface, incisal, middle, cervical area were measured and a circular area of 1.0mm in diameter was measured at each site by the spectrophotometer. The obtained results of this study were as follows: 1) Natural tooth color showed a significant decrease in linghtness($L^*$) at the cervical site(P<0.05). 2) Red/green chromaticity($a^*$) showed a significant increase at all sites(P<0.01). But it was not enough to have a statistic significance among three sites by aging. 3) Yellow/blue chromaticity($b^*$) showed an increase at all sites(P<0.05). But it didn't change significantly among three sites by aging.

• Journal of IKEEE
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• v.13 no.3
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• pp.72-79
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• 2009

This paper describes a compact microstrip active antenna with dual polarization. The antenna, receiving both a left-hand circularly polarized wave and a right-hand circularly polarized wave, has a function of polarization diversity. A square-shaped empty room is located on the inside of the microstrip radiator so that the size has been reduced. And slots are added around feeding point to improve input matching. Also, amplifier and switching circuitry are placed at the empty room to increase antenna gain and to select one of the circular polarizations, respectively. The proposed antenna has been applied to GPS(global positioning system). The measurement results show that it has 10dB-impedance bandwidth, 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 90degree, and gain of 13dBi, respectively, for RHCP. Also, it has 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 84 degree, and gain of 12dBi, respectively, for LHCP.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.4
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• pp.69-76
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• 2005

In this paper, a 2 stage 6-pole bandpass filter(BPF) is designed and implemented by using triple-mode cavity for satellite payload system. The BPF has a 100MHz bandwidth at the center frequency of 14.5GHz(Ku-band) and the response of the filter is the Chebyshev function. The cavity filter uses two orthogonal $TM_{113}$ modes and one $TM_{012}$ mode. The coupling between the adjacent cavityes(intercavity coupling) results in a Chebyshev response and is accomplished by only H-filed component of If modes. The size and location of intercavity slot is determined by the coupling equation from E-and H-field of TE and TM resonant modes in circular cavity. The 2-stage 6-pole triple-mode cavity BPF has the insertion loss of 2.4dB and the reflection loss of 15dB in the passband. The triple-mode BPF proposed in this thesis can be used as channel filters for satellite payload system and can minimize filter assembly in general wireless communication system.

• Journal of Gastric Cancer
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• v.20 no.1
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• pp.72-80
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• 2020

Purpose: Proximal gastrectomy (PG) is a function-preserving surgery in cases of proximally located early-stage gastric cancer. Because gastroesophageal reflux is a major pitfall of this operation, we devised a modified esophagogastrostomy (EG) anastomosis to fix the distal part of the posterior esophageal wall to the proximal part of the anterior stomach wall to produce an anti-reflux mechanism; we named this the SPADE operation. This study aimed to show demonstrate the clinical outcomes of the SPADE operation and compare them to those of previous PG cases. Materials and Methods: Case details of 56 patients who underwent PG between January 2012 and March 2018 were retrospectively reviewed: 30 underwent conventional esophagogastrostomy (CEG) anastomosis using a circular stapler, while 26 underwent the SPADE operation. Early postoperative clinical outcome-related reflux symptoms, endoscopic findings, and postoperative complications were compared in this case-control study. Results: Follow-up endoscopy showed more frequent reflux esophagitis cases in the CEG group than in the SPADE group (30% vs. 15.3%, P=0.19). Similarly, bile reflux (26.7% vs. 7.7%, P=0.08) and residual food (P=0.01) cases occurred more frequently in the CEG group than in the SPADE group. In the CEG group, 13 patients (43.3%) had mild reflux symptoms, while 3 patients (10%) had severe reflux symptoms. In the SPADE group, 3 patients (11.5%) had mild reflux symptoms, while 1 had severe reflux symptoms (absolute difference, 31.8%; 95% confidence interval, 1.11-29.64; P=0.01). Conclusions: A novel modified EG, the SPADE operation, has the potential to decrease gastroesophageal reflux following a PG.

• BMB Reports
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• v.41 no.5
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• pp.369-375
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• 2008

Polygonatum cyrtonema Lectin (PCL), which is classified as a monocot mannose-binding lectin, has received great regards for its uniquely biological activities and potentially medical applications in cancer cells. This paper was initially aimed to study apoptosis of PCL on Hela cells. Thus, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) method was carried out. Through observation of cell morphologic changes and Lactate dehydrogenase (LDH) activity-based cytotoxicity assays, PCL induced HeLa cell apoptosis in a dose-dependent manner. To further gain structural basis, multiple alignments, homology modeling and docking experiments were performed to analyze the correlation between its biological activities and mannose-binding sites. Eventually, considering docking data, chemical modification properties on the three mannose-binding sites were analyzed by a series of biological experiments (e.g., hemagglutinating and mitogenic activity assays, fluorescence and Circular Dichrosim (CD) spectroscopy) to profoundly identify the role of some key amino acids in the structure-function relationship of PCL.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.183-188
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• 1997

A method for designing a broadband transducer was investigated experimentally. Control of the resonance frequency of a Piezoelectric circular transducer with two pairs of electrodes was achieved by varying the inductance of external coil connected across the terminal of one pair of electrodes of transducer. The conductance curves of transducer in water were obtained as a function of the inductance value in mH of the coil used in the tuning. As the tuning inductance is increased in value, the resonance frequency is reduced toward the fundamental frequency of 50 kHz. This interesting result suggest that it is possible to produce a continuously tunable transducer covering a frequency range between 61.3 kHz and 121.7 kHz by varying the inductance value of external coil from 2.7 mH to 15.0 mH. One of other problems in the design and construction of such broadband transducer is the transducer efficiency, but this will be the subject of our future work.