• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.73-89
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• 1991

Impression ragistration is an improtant and difficult phase of prosthodontic treatment procedures and a tray of appropriate size and shape is essential to obtain the accurate impression. Particularly, in edentulous patients, the size and forms of their residual alveolar ridges are different from one another. Therefore, in this study, various measurements were taken on the edentulous models. And the measurements were analyzed and compared with one another. The results were as follows ; 1. The mean of denture bearing area was $32.86cm^2$ in the upper jaws, $24.20cm^2$ in the lower jaws and the variation of denture bearing area was greater in the upper than in the lower jaws and in males than in females. 2. The mean of A-P(anteroposterior) ridge length was 48.72mm in the upper jaws, 53.05mm in the lower jaws and that of males was longer than that of females. 3. The mean of most posterior ridge width was 47.23mm in the upper jaws, 58.03mm in the lower jaws and the difference of that between males and females was least in both jaws. 4. In the upper jaws, the mean of ridge width was 29.66mm on anterior 1/4, 42.79mm on middle, 48.95mm on posterior 1/4 line and the mean of palatal height was 4.56mm on anterior 1/4, 10.01mm on middle, 10.84mm on posterior 1/4 line. 5. In the lower jaws, the mean of ridge width was 33.24mm on anterior 1/4, 50.19mm on middle, 59.16mm on posterior 1/4 line and the mean of lingual ridge height was 5.49mm on anterior 1/4, 9.16mm on middle, 16.72mm on posterior 1/4 line. 6. The correlation coefficient(=r) between denture bearing area and A-P ridge length was 0.83 in the upper jaws and 0.75 in the lower jaws. The corelation between denture bearing area and AP ridge length was statistically significant, but, between denture bearing area and A-P ridge length and between A-P ridge length and the most posterior ridge width was not statistically significant in both jaws. 7. Alveolar ridge forms were classified into three(ovoid, "u" shape, and "v"shape) categories. In the upper jaws, ovoid was 66%, "u" shape was 24%, and "v" shape was 10%, in the lower jaws, ovoid was 66.7%, "u" shape was 20%, and "v" shape was 13.3%.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.19-24
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• 2024

In this paper, in order to realize lower cut-off frequency of the waveguide, the folded Ridge waveguide (FRWG) is suggested by alternating T-shape structure in the conventional folded waveguide with Y-shape structure. Suggested FRWG can be equivalent by the reverse Ridge waveguide. As the height of side of the FRWG is lower, the width of side is increased. Therefore, the cut-off frequency of the FRWG can be decreased more than half compared with conventional waveguide. The FRWG is designed with the length, height, and width of Y-shape structure of 40mm, 20mm, and 2mm, respectively. Designed FRWG has the cut-off frequency of the 1.996GHz. Also, the transition between the FRWG and SMA connector is designed. The transition is optimized by the capacitance of the signal line of the connector. Its result shows the VSWR under 2:1 in the band of 2.064 ~ 3.050 GHz. Suggested FRWG can be applied with miniaturization of various waveguide devices.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.2
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• pp.67-73
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• 2005

Recently, the social requirement of personal identification techniques has been increasing. Fingerprint recognition is one of the biometries methods that has been widely used for this requirement. This paper proposes the fingerprint matching algorithm that uses the information of the ridge shapes of minutiae. In which, the data of the ridge shape are expressed in one-dimensional discrete-time signals. In our algorithm, we obtain one-dimensional discrete-time signals for ridge at every minutiae from input and registered fingerprints, and find pairs of minutia which have the similar ridge shape by comparing input fingerprint with registered fingerprint, thereafter we find candidates of rotation angle and moving displacement from the pairs of similar minutia, and obtain the final rotation angle and moving displacement value from those candidates set by using clustering method. After that, we align an input fingerprint by using obtained data, and calculate the matching rate by counting the number of corresponded pairs of minutia within the overlapped area of an input and registered fingerprints. As a result of experiment, false rejection rate(FRR) of $18.0\%$ at false acceptance rate(FAR) of $0.79\%$ is achieved.

• The Journal of the Korean dental association
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• v.57 no.12
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• pp.768-777
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• 2019

Alveolar bone resorption are unpredictable and always occur after tooth extraction. Such bone resorption causes insufficient alveolar ridge which make implant placement difficult. There are many techniques to increase the alveolar ridge. Representative procedures include ridge split, guided bone regeneration, bone graft using autogenous block bone, and alveolar distraction. In each procedure, there are indications and complications. Depending on the shape and the width of bone defects, we can choose procedures for horizontal bone augmentation and vertical bone augmentation.

• Journal of the Korean Institute of Navigation
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• v.22 no.4
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• pp.37-44
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• 1998

This paper presents a procedure for automated extraction of ridge shadows in noisy gray images. This procedure mainly consists of 1) a deformable model which is designed basing upon the knowledge about the shape of shadows and is expected to be useful in extracting ridge shadows especially located in low signal to noise ratio background, and 2) the scale space scheme which is also useful even if there is less information about the size and the positions of ridge shadows in advance. This procedure is applied to artificial images and its performance is evaluated experimentally.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.100-100
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• 2022

This study was conducted in 2021 using Kwangpyeongok and Gangdaok, that showed good yield performance both under upland and lowland conditions in the previous year. The experiments were carried out by sowing on April 22, May 14, May 30, June 19, and July 10, with aim to determine optimum sowing date in central region of Korea. The growing degree days (GDD) required to read the flowering stage were 1375.5-1725.3℃ for upland and 1582.7-1982.4℃ for lowland condition. The lowest GDD was observed in July 10 sowing regardless of ridge formation both under lowland and upland conditions for Kwangpyeongok. However, Gangdaok showed the lowest GDD under no-ridge in lowland and high-ridge in upland, both of which were sown on June 19. The difference in GDD between no-ridge and high-ridge treatment was little depending on the sowing date. In both lowland and upland, there was no significant difference between no-ridge and high-ridge treatments in stover dry matter, ear dry matter, and TDN between no-ridge and high-ridge treatments. Under upland condition, no significant difference in biomass and TDN was observed among sowing date treatments and between varieties. Under lowland condition, biomass production was severely reduced in May 30 sowing treatment, whereas no varietal difference was observed. Reduced biomass in May 30 sowing treatment may be due to excess waterlogging and lodging by rainfall.

• Journal of the korean society of oceanography
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• v.32 no.4
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• pp.181-190
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• 1997

A large subtidal sand ridge (Jungang Satoe) in Asan Bay, on the west coast of Korea, was studied in order to understand the morphology and sediment transport trend in a macrotidal setting, by means of analyzing sediment samples, current data, side-scan sonographs and seismic profiles. The ridge is about 15 km long and 2-5 km wide, with a relief of about 15 m. It is elongated in the flow direction of flood (SE) and ebb (NW) tidal currents, but asymmetrical in cross section. The western and southwestern side of the ridge is characterized by relatively gentle slopes averaging 0.4$^{\circ}$, whereas on the northeastern side, relatively steep slopes were mapped with 1.6$^{\circ}$ slope angles. Tidal currents associated with the ridge are very strong; maximum surface velo-cities range from neap values of 50 cm/s to spring values of 130 cm/s. The shear velocities during flood and ebb are strong enough to erode and transport sands on the ridge. Sand waves and megaripples (dunes) are the most common bedforms produced by the tidal currents, which show regional differences in shape and size on the ridge. The distribution pattern of these bedforms in-dicates that the flood tidal currents are dominant on the offshore (northwest) side of the ridge, whereas the onsho.e (southeast) side of the ridge is ebb-dominated. The sand transport path as inferred from bedform orientations is directed toward the ridge crest on the flanks, whereas on the crest, it is near-longitudinal to the ridge axis. The convergent, upslope movement of sands on the ridge flanks appears to be important in sand ridge building and maintenance. A significant ridge migration toward the northeast can be suspected on the basis of the ridge morphology, which may cause offshore hazards for navigation.

• Journal of Ocean Engineering and Technology
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• v.16 no.1
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• pp.27-35
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• 2002

The interaction of grounded ice ridges with underlying seabed is one of the major considerations in the design of Arctic pipeline system. Previously several ice scour models were developed by researchers to describe the ice scour-seabed interaction mechanism. In view of possible improvements, a comparative study of those ice scour models is performed and their limitation in modeling is discussed. Simple laboratory tests are carried out and then the shape pattern of deposited soil around the ice model is newly defined. Unlike the rectangular idealization of an ice block, in this modified ice scour model, trapezoidal cross sections are assumed to represent the typical shape of an ice ridge based on the field observation data. With the horizontal and vertical motion of ice model, the ice scour depth and soil reacting forces on seabed are calculated with varying the keel angle of an ice ridge.

• 한국해양학회지
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• v.29 no.3
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• pp.278-286
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• 1994

Tidal sand ridges, which develop in Kyeonggi Bay generally parallel to the direction of tidal current on the sea bottom are also well shown in seismic profiles, surface and core samples were obtained from sand ridge field near the Palmi Do for the study of origin and sedimentary environments of these sand ridges. Sand ridge field near Palmi Do can be divided into 3 seismic units(unit A, B, C), and each unit has one sand ridge(ridge A, B, C), Ridge A that shows clinoform prograding southeastwards is generally parallel with tidal current trending northeast to southwest(40$^{\circ}$). It means that sand ridge is migrating to southward. Unit B includes a sand ridge and a channel fill structure in seismic profiles. Compared with ridge A, ridge B has similar direction, magnitude and internal reflectors. So ridge B developed in the similar sedimentary environments to ridge A about 10 m lower than present sea level. As the rise of sea level, channel fill structure formed as the deposit of fine sediments with the shape of conformable bedding or horizontal bedding.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.628-631
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• 1988

This paper describes a fingerprint classification on the basis of feature points(whorl, core) and feature vector and uses a syntactic approach to identify the shape of flow line around the core. Fingerprint image is divided into 8 by 8 subregions and fingerprint region is separated from background. For each subregion of fingerprint region, the dominant ridge direction is obtained to use the slit window quantized in 8 direction and relaxation is performed to correct ridge direction code. Feature points(whorl, core, delta) are found from the ridge direction code. First classification procedure divides the types of fingerprint into 4 class based on whorl and cores. The shape of flow line around the core is obtained by tracing for the fingerprint which has one core or two core and is represented as string. If the string is acceptable by LR(1) parser, feature vector is obtained from feature points(whorl, core, delta) and the shape of flow line around the core. Feature vector is used hierarchically and linearly to classify fingerprint again. The experiment resulted in 97.3 percentages of sucessful classification for 71 fingerprint impressions.