• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.371-376
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• 2003

As Mobile Internet gets more popular, the switchover of E-Commerce to M-Commerce gets faster and many service providers offer diverse M-Commerce service by using mobile technology. Also, as M-Commerce makes rapid progress, the security protocol gets more widely recognized for its significance. In particular, WAKE(Wireless Authentication and Key Establishment) protocol carried out wirelessly is of great importance, since the user and service provider must get through to carry out the M-Commerce. Key recovery method is a part of the key management in order to provide an emergency recovery of key whenever necessary, like when the user lost the key or the cryptosystem was illegally used. The ASPeCT project first tried to support the key recovery function in WAKE Protocol Since then, a variety of WAKE Key Recovery protocols have been proposed. In this thesis, problems of WAKE Key Recovery protocols proposed so far are analyzed and new WAKE Key Recovery protocol is suggested to solve those problems.

• Journal of Korean Neurosurgical Society
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• v.63 no.2
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• pp.237-247
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• 2020

Objective : Fixation of the C1-2 segment is challenging because of the complex anatomy in the region and the need for a high degree of accuracy to avoid complications. Preoperative 3D-computed tomography (CT) scans can help reduce the risk of complications in the vertebral artery, spinal cord, and nerve roots. However, the patient may be susceptible to injury if the patient's anatomy does not match the preoperative CT scans. The intraoperative 3D image-based navigation systems have reduced complications in instrument-assisted techniques due to greater accuracy. This study aimed to compare the radiologic outcomes of C1-2 fusion surgery between intraoperative CT image-guided operation and fluoroscopy-guided operation. Methods : We retrospectively reviewed the radiologic images of 34 patients who underwent C1-2 fusion spine surgery from January 2009 to November 2018 at our hospital. We assessed 17 cases each of degenerative cervical disease and trauma in a study population of 18 males and 16 females. The mean age was 54.8 years. A total of 139 screws were used and the surgical procedures included 68 screws in the C1 lateral mass, 58 screws in C2 pedicle, nine screws in C2 lamina and C2 pars screws, four lateral mass screws in sub-axial level. Of the 34 patients, 19 patients underwent screw insertion using intraoperative mobile CT. Other patients underwent atlantoaxial fusion with a standard fluoroscopy-guided device. Results : A total of 139 screws were correctly positioned. We analyzed the positions of 135 screws except for the four screws that performed the lateral mass screws in C3 vertebra. Minor screw penetration was observed in seven cases (5.2%), and major pedicle screw penetration was observed in three cases (2.2%). In one case, the malposition of a C2 pedicle screw was confirmed, which was subsequently corrected. There were no complications regarding vertebral artery injury or onset of new neurologic deficits. The screw malposition rate was lower (5.3%) in patients who underwent intraoperative CT-based navigation than that for fluoroscopy-guided cases (10.2%). And we confirmed that the operation time can be significantly reduced by surgery using intraoperative O-arm device. Conclusion : Spinal navigation using intraoperative cone-beam CT scans is reliable for posterior fixation in unstable C1-2 pathologies and can be reduced the operative time.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.11
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• pp.32-41
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• 2000

A new anatomical head model was implemented based on the MR and CT images of the head of a volunteer whose head shape is close to the domestic standard. In order to compare SARs (specific absorption rates) of heads with different shapes, we calculated SARs in the two anatomical head models. The one is the new model and the other is that of the black race and was made at National Library Medicine in USA. The head model and a phone model were arranged in the computational space to be the touch or cheek position of CENELEC (European Committee for Electrotechnical Standardisation) and FCC guidelines. From the obtained results, we can see that the smaller head produces the higher whole head-averaged SAR. However, it seems that the localized SAR averaged over 1 g or 10 g is more dependent on the shape of the auricle rather than that of the head size.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.776-787
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• 1998

This paper analyzes the local specific absorption rates (SAR's) averaged over 1 g and 10 g in a human head model in contact with a mobile phone operating at 835 MHz. The used numerical method is a total field finite-difference time-domain (FDTD) technique. The phone was simulated with a conducting box, a plastic case, and a whip antennal composed of a monopole and a helix. The discrete human model of the spatial resolution 3 mm is based on Magnetic Resonance Imaging (MRI), computerized tomography (CT) and anatomical images. The near field and far field and far field patterns were analyzed for extended and retracted phone. The two methods to take the volumes of the weights, 1 g or 10 g in tissue are proposed and compared to offer a reproductive technique for SAR estimations.

• Imaging Science in Dentistry
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• v.31 no.3
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• pp.175-179
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• 2001

Cystic lymphangioma is an uncommon benign developmental tumor of the lymphatic system, seen rarely in adults. A 23-year-old man visited DKUDH complaining of the painless swelling in the right submandibular area. It was reported that swelling had increased since 5 months ago. Clinically, fltriangle uctuant and mobile mass was palpated at the right submandibular area. CT scan showed a large, well-defined, homogenous low density mass, measuring 5.0 × 2.5 × 4.0 cm. T1W MRI scan demonstrated a large, multiseptated homogenous low signal mass with septum and rim enhancement. Proton-density and T2W MRI scan showed mass of high signal intensity. MRI scan was able to delineate better the enhanced multi septation and extent of the lesion. Histopathologically, a lobulated cystic mass lined by a layer of flattened endothelium was observed.

• Imaging Science in Dentistry
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• v.34 no.2
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• pp.111-116
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• 2004

Rhabdomyosarcoma, when it occurs in the head and neck, is primarily found in children. Alveolar rhabdomyosarcoma is rarely seen in the oral lesion, comparing to the embryonal and the pleomorphic variants. This is a report of a case of alveolar rhabdomyosarcoma in the mandible in a ten-year old girl who complained of a non-painful swelling on the right cheek. The right lower 1st molar was mobile. Her radiographs revealed an extensive radiolucency with somewhat irregular border on the right mandibular ramus. The right mandibular 1st and 2nd molars lost their lamina dura and were floating. CT images revealed smooth-outlined soft tissue mass occupying the pterygomandibular space, the infratemporal space, and the masseteric muscle with thinning and perforation of the right mandibular angle and ramus. Histopathological and immunohistochemical findings established the final diagnosis of alveolar rhabdomyosarcoma.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.407-410
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• 2000

본 연구에서는 UMTS[1]에서의 보안 서비스를 실험하고 검증하기 위한 ASPeCT[2]에서 제시한 AIP[3,4] 프로토콜을 위한 개선된 키 복구 프로토콜을 제안한다. AIP 프로토콜은 사용자와 VASP 간에 이루어지는 인증과 지불 초기화를 위한 프로토콜이며 이를 기반으로 하여 이동 통신 기반의 전자상거래가 실현될 수 있다. 제안된 키 복구 프로토콜은 검증 가능한 비밀 공유 프로토콜[5,6,7]을 기반으로 하여 다수의 키 복구 기관과의 연관을 통하여 개선된 안전성을 제공하고 악의적인 사용자가 잘못된 비밀 정보를 키 복구 기관(KRA)에게 위탁하는 것을 방지한다.

• Advances in pediatric surgery
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• v.16 no.1
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• pp.43-48
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• 2010

Gastric trichobezoars are commonly observed in young women with trichotillomania and trichophagia. We encountered an 8-year-old girl who had trichotillomania and trichophagia with abdominal pain and a mass, which was diagnosed as a large gastric trichobezoar. On physical examination, a huge, firm nontender mobile mass was palpated in her epigastrium. An upper gastrointestinal series and abdominal computed tomography (CT) scan showed a large mass in the stomach. Endoscopic removal was tried but failed. Laparoscopic removal was therefore performed. The trichobezoar was successfully retrieved through a gastrotomy and removed through an extended umbilical trocar incision. This case demonstrates that laparoscopic removal of large gastric trichobezoars is feasible and safe without a large abdominal incision.

• The Journal of the Korea Contents Association
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• v.12 no.3
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• pp.480-486
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• 2012

There has been an increasing interest in new industry and demand creations by the convergence and integration between IT and infrastructure and BT, NT, and CT and the convergence of IT and spread of cloud computing have changed the IT service environment. Even in the educational field, the convergence and integration of contents with various IT have rapidly emerged and learning equipments for the educational purpose have expanded to the mobile media platform from PCs so that learning without limitations to time, place and equipment has become possible. Contents necessary for the smart education are under way by research development utilizing cyber reality and simulation, and 3D technologies. The purpose of this study is to propose marine contents use and service plans for the educational purpose in order to produce various types of contents for the marine life and environment, to improve the school achievement by stimulating interest and to provide individually customized learning.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.542-558
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• 2023

A digital focus index (DFI) is a value used to determine image focus in scientific apparatus and smart devices. Automatic focus (AF) is an iterative and time-consuming procedure; however, its processing time can be reduced using a general processing unit (GPU) and a multi-core processor (MCP). In this study, parallel architectures of a minimax search algorithm (MSA) are applied to two DFIs: range algorithm (RA) and image contrast (CT). The DFIs are based on a histogram; however, the parallel computation of the histogram is conventionally inefficient because of the bank conflict in shared memory. The parallel architectures of RA and CT are constructed using parallel reduction for MSA, which is performed through parallel relative rating of the image pixel pairs and halved the rating in every step. The array size is then decreased to one, and the minimax is determined at the final reduction. Kernels for the architectures are constructed using open source software to make it relatively platform independent. The kernels are tested in a hexa-core PC and an embedded device using Lenna images of various sizes based on the resolutions of industrial cameras. The performance of the kernels for the DFIs was investigated in terms of processing speed and computational acceleration; the maximum acceleration was 32.6× in the best case and the MCP exhibited a higher performance.