• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.217-218
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• 2010

• Journal of Korean Neurosurgical Society
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• v.47 no.1
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• pp.36-41
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• 2010

Objective: The aim of this study was to investigate the morphological characteristics of the thalamoperforating arteries that arise from the P1 segment of the posterior cerebral artery. Methods: Thalamoperforating arteries located in the interpeduncular fossa were dissected in 26 formalin-fixed human cadaver brains. We investigated the origin site of thalamoperforating arteries from the P1 segment, number and diameter. and variations in their origin. Results: Thalamoperforating arteries arose from the superior, posterior or posterosuperior surfaces of the P1 segment at the mean 1.93 mm (range, 0.41-4.71 mm) distance from the basilar apex and entered the brain through the posterior perforated substance. The average number was 3.6 (range 1-8) and mean diameter was 0.70 mm (range 0.24-1.18 mm). Thalamoperforating arteries could be classified into five different types according to their origin at the P1 segment: Type I (bilateral multiple), 38.5%; Type II (unilateral single, unilateral multiple), 26.9%; Type III (bilateral single), 19.2%; Type IV (unilateral single), 11.5%; Type V (unilateral multiple), 3.8%. In 15.4% of all specimens. thalamoperforating arteries arose from the only one side of P1 segment and were not noted in the other side. In such cases, the branches arising from the one side of P1 segment supplied the opposite side. Conclusion: Variations in the origin of the thalamoperforating arteries should be keep in mind to perform the surgical clipping, endovascular treatment or operation involving the interpeduncular fossa. In particular, unilateral single branch seems to be very risky and significant for surgical technique or endovascular treatment.

• Animal Systematics, Evolution and Diversity
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• v.39 no.4
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• pp.176-211
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• 2023

Nine copepod species of the family Artotrogidae Brady, 1880 are described or redescribed from Korea. Included new species are two in the genus Artotrogus Boeck, 1859, one each in the genera Bradypontius Giesbrecht, 1895, Cryptopontius Giesbrecht, 1899, Neopontius Scott T., 1898 and Chejupontius n. gen., and two in the genus Sewellopontius Ummerkutty, 1966. Chejupontius n. gen. resembles Ascidipontius Kim I. H., 1996, Pulicitrogus Kim I. H., 1998, and Sewellopontius in having reduced armature of leg 1, but is distinguished from these and other genera of the family by the large, mediodistally expanded protopod of leg 5 and by a combination of characters exhibited in leg 1 that the first exopodal segment lacks an inner seta, the second exopodal segment lacks an outer spine, the third exopodal segment is armed with three spines plus one to three setae, and the second endopodal segment is armed with a single inner seta. Pteropontius cristatus Giesbrecht, 1895 known previously only from the Mediterranean Sea is redescribed, based on a newly collected specimen from Korea, and P. trimerus Kim I. H., 1996 is removed to the genus Sewellopontius. A short note is given for the epibiotic suctorian Thecacineta calix (Schroder, 1907) which was found attached to the antennule of a new copepod species.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.619-631
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• 1993

Tooth movement by segment is one of the means which are frequently used in daily orthodontic practice. When we retract or intrude a tooth or teeth, we should recognize the center of resistance of the certain tooth or teeth. There have been many studies about the center of resistance of a single tooth, not so much was about the tooth-segment. At the present study the center of resistance of the maxillary anterior segment is experimentally investigated by using laser reflection technique and metal splints on the human dry skull. The variables of intrusive force magnitude are divided into two groups, 50g and 100g groups. The results were as follows ; 1. The center of resistance of the maxillary anterior segment composed of the central and lateral incisors was at the mesial portion of canine crown at the coronal level. 2. The center of resistance of the maxillary anterior segment composed of the central and lateral incisors and canines is between the canine and the 1st premolar crowns at the coronal level.

• Geomechanics and Engineering
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• v.15 no.3
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• pp.833-839
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• 2018

Dynamic behaviour of a tunnel is one of the most important issues for the safety and it is generally subjected to the seismic response of the surrounding soil. Relative displacement occurred in tunnel lining during earthquake produces severe damage. Generally, it concentrates at the connecting area when two tunnels are connected in the ground. A flexible segment is a useful device for the mitigation of seismic loads on tunnel lining. In this study, 1-g shaking table tests are performed to investigate the acceleration response for the verification of the effect of flexible segment and to determine the optimum location of the flexible segment for connected tunnels. Four different seismic waves are considered; as a result, peak acceleration is reduced to 49% in case that flexible segment is implemented adjacent to connecting area. It also exhibited that the mitigation of acceleration response is verified in all seismic waves. Additionally, 3-dimensional numerical analysis is performed to compare and verify the results. And the numerical results show good agreement to those of the experimental study.

• The Transactions of the Korea Information Processing Society
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• v.6 no.8
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• pp.2213-2221
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• 1999

A line segment has a symmetrical property about its midpoint. With this symmetrical property for a line segment we have proposed a variant of Bresenham's line drawing algorithm that selects two pixels at the same time. It implies that bi-directional line drawing toward the midpoint of line segment from each-end be possible. Besiders, it can select two pixels using only one decision parameter, instead of two different parameters for each pixel. We also present a theoretical proof for the correctness of such a selection. Thus, we can reduce the time of generating line segment by approximately less than 5% compared to the Bresenham's method. Also, our experimental results show that the shape of line segment generated by the proposed approach is the exactly same as that of Bresenham's method.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.26 no.1
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• pp.37-45
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• 2024

Objective: To review the characteristics of distal middle cerebral artery (MCA) aneurysm treated by microsurgery, the detailed surgical options, and the clinical result. Methods: We retrospectively reviewed cerebral aneurysm in the M2 and M3 segments of the MCA surgically treated between January 2015 and December 2022. The demographic data, aneurysm-related findings, type of surgical approach, surgical technique, and clinical outcomes of the enrolled patients were analyzed. Results: Sixteen distal MCA aneurysms were treated with microneurosurgery (incidence, 1.0%; female, 12; mean age, 58.1 years; ruptured, three). Twelve aneurysms were in the M2 segment (insular segment), two aneurysms at the M2-M3 junction, and two aneurysms in the M3 segment (opercular segment). Twelve aneurysms were saccular (average size, 4.9 mm; multiplicity, 50%; average aneurysms, 3.0; partially thrombosed, 1; sidewall aneurysm, 2). Three aneurysms were fusiform, of which two were ruptured. Of the ruptured aneurysms, one was a ruptured dissecting aneurysm. The trans-sylvian and trans-sulcal approaches were used in fourteen and two patients, respectively. Neck clipping, wrap clipping, and surgical trapping were performed in twelve, one, and one patient, respectively. Proximal occlusion was performed in one patient. Bypass technique was required in two patients (neck clipping and proximal occlusion). The modified Rankin Score was 6 in the two patients with ruptured aneurysms. The remaining patients did not show further neurological deterioration after microneurosurgery. Conclusions: Distal MCA aneurysms had a high incidence of being diagnosed with multiple other aneurysms and were relatively non-saccular.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.503-515
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• 2017

Underground structures that have recently become larger are required to be stable not only during normal times but also during earthquakes. Especially, it is very important to maintain the stability of the subsea tunnels during the earthquake. The objective of this paper is to verify the effectiveness of the flexible segment, which is one of the breakthrough facilities to maintain the stability of the subsea tunnel during the earthquake using the shaking table test. Another goal of this paper is to propose the optimum position of the flexible segment through 3D dynamic numerical analysis based on the verified results from shaking table tests. The 1g shaking table test considering the similarity ratio (1:100) to the cross section of the selected artificial subsea tunnel was carried out considering the Geongju and Artificial seismic waves, longitudinal and lateral wave, and with/without flexible segments eight times or more. As a result of the shaking table test, it was confirmed that the flexible segment is effective in improving the seismic performance of the undersea tunnel in all the experimental results. In addition, 3D dynamic numerical analysis was performed to select the optimum position of the flexible segment which is effective for improving seismic performance. As a result, it was confirmed that the seismic acceleration is attenuated when the flexible segment is installed adjacent to the branch section in subsea tunnel.

• Animal Systematics, Evolution and Diversity
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• v.23 no.2
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• pp.127-133
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• 2007

A new genus Goodingius is proposed to incorporate Hemicyclops adhaerens(Williams), H. arenicolae Gooding, H. elongatus Wilson and H. subadhaerens Gooding, all of which bear the six-segmented female urosome, three mandibular elements (or three elements plus one rudimentary setule), five setae on the first antennular segment, and no inner coxal seta of leg 4. The genus Giardella Canu, a sister taxon of Goodingius, is redefined as possessing eight elements on the third exopodal segment of leg 3, only a single inner seta on the second endopodal segment of leg 4, four spines on the third endopodal segment of leg 4. To the genus Giardella, Hemicyclops caissarum Kihara and Rocha and H. carinifer Humes are assigned, in addition to Giardella ricoensis n. sp., Giardella callianassae Canu, and G. thompsoni A. Scott. Keys to the species of both genera are provided.

• Geomechanics and Engineering
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• v.29 no.4
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• pp.471-486
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• 2022

The effect of segmental joints is one of main importance for the segmental lining design when tunnels are excavated by a mechanized process. In this paper, segmental tunnel linings are analyzed by two numerical methods, namely the Beam-Spring Method (BSM) and the Solid-Interface Method (SIM). For this purpose, the Tehran Subway Line 6 Tunnel is considered to be the reference case. Comprehensive 2D numerical simulations are performed considering the soil's calibrated plastic hardening model (PH). Also, an advanced 3D numerical model was used to obtain the stress relaxation value. The SIM numerical model is conducted to calculate the average rotational stiffness of the longitudinal joints considering the joints bending moment distribution and joints openings. Then, based on the BSM, a sensitivity analysis was performed to investigate the influence of the ground rigidity, depth to diameter ratios, slippage between the segment and ground, segment thickness, number of segments and pattern of joints. The findings indicate that when the longitudinal joints are flexible, the soil-segment interaction effect is significant. The joint rotational stiffness effect becomes remarkable with increasing the segment thickness, segment number, and tunnel depth. The pattern of longitudinal joints, in addition to the joint stiffness ratio and number of segments, also depends on the placement of longitudinal joints of the key segment in the tunnel crown (similar to patterns B and B').