• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제11권sup1호
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• pp.55-71
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• 2008

Gastroesophageal reflux (GER) defined as passage of gastric contents into the esophagus without symptoms is a common physiologic gastrointestinal problem in infants, children and even in adults. But gastroesophageal reflux disease (GERD) defined as symptoms or complications of GER is a disease entity to find out the reason and treat. After the era of 1970 we have been studying about GERD with the development of diagnostic and therapeutic methods. I already introduced the nature and the fundamental knowledge of GERD in the opening symposium of KSPGHAN in 1998. Now, I will introduce the guidelines for evaluation and treatment of GERD which was recommended by the North American Society for Pediatric Gastroenterology and Nutrition and American Pediatric Association which was published in 2001. And I will introduce progressing subjects and the forecoming issues to be solved in near future. Those are as followings. Does GERD cause otolaryngologic symptoms such as chronic sinusitis and chronic otitis? Is GERD inherited? Can we find out the child who will become GERD in adult life and the way to reduce the incidence of Barrett's esophagus and esophageal cancer? Is long term PPI therapy safe in children?

• 정보보호학회논문지
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• 제10권1호
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• pp.89-97
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• 2000

공개키 암호 시스템 중에서 가장 널리 사용되는 RSA 암호 시스템은 키의 분배와 권리가 용이하고, 디지털 서명이 가능한 장점이 있으나, 암호화와 복호화 과정에서 512 비트 이상의 큰 수에 대한 멱승과 모듈라 감소 연산이 요구되기 때문에 처리 속도의 지연이 큰 문제가 되므로 모듈라 멱승 연산의 고속 처리가 필수적이다. 따라서 본 논문에서는 몫을 추정하여 중간 곱의 크기를 제한하는 interleaved 모듈라 곱셈 기법을 이용하여 모듈라 멱승 연산을 수행하는 고속 RSA 암호 칩을 VHDL을 이용하여 모델링하고 Faraday FG7000A 라이브러리를 이용하여 합성하고 타이밍 검증하여 단일 칩 IC로 구현하였다. 구현된 암호 칩은 75,000 게이트 수준으로 합성되었으며, 동작 주파수는 50MHz이고 1회의 RSA 연산을 수행하는데 소요되는 전체 클럭 사이클은 0.25M이며 512비트 당 처리 속도는 102.4Kbit/s였다.

• BMB Reports
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• 제40권2호
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• pp.142-150
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• 2007

Epigenetic alterations, represented by aberrant DNA methylation, are deeply involved in human cancers. In gastric cancers, tumor-suppressor genes are inactivated more frequently by promoter methylation than by mutations. We recently showed that H. pylori infection, a potent gastric carcinogenic factor, induces methylation of specific genes in the gastric mucosae. When the methylation levels were analyzed in the gastric mucosae of healthy volunteers, cases with a single gastric cancer, and cases with multiple gastric cancers, who have increasing levels of risks for gastric cancers, there was a significant increasing trend in the methylation levels among the individuals without current H. pylori infection. This finding unequivocally showed the presence of an epigenetic field for cancerization. The degree of the field defect was measured more conveniently using methylation levels of marker genes than using those of tumor-suppressor genes. The presence of an epigenetic field for cancerization has been indicated for liver, colon, Barrett's esophageal, lung, breast, and renal cancers. Since decreased transcription is involved in the specificity of methylated genes, it is likely that specific genes are methylated according to carcinogenic factors. These findings emphasize the usefulness of DNA methylation as a marker for past exposure to carcinogens and future risk of cancer development.

• 대한기관식도과학회지
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• 제9권1호
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• pp.30-38
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• 2003

Cancers of the cervical esophagus occur uncommonly, but treatment is remaining a challenging problem and surgery demands special knowledge of abdominal, thoracic, and neck surgery. The primary risk factor is chronic heartburn, leading to a sequence of esophagitis, Barrett's esophagus, reflux esophagitis and etc. Among the various treatment modalities, Surgery is still a mainstay of treatment. The main aim of surgery is not only oncologically adequate resection but also preservation or restoration of physiologic functions, such as deglutition and phonation. Surgical treatment of cervical esophageal cancer is influenced by special problems arising from tumor factors, patient factors and surgeon factors. Complete clearance of loco-regional disease and prevention of postoperative complications are of particular importance for the improvement of long-term survival in patients with these cancers. So the cervical and thoracic extension of these tumors usually required an extensive lymphadenectomy with primary resection. Radical resection of the primary site almostly include sacrifice of the larynx, but the voice could be rehabilitated with various methods, such as tracheoesophageal prosthesis or tracheoesophageal shunts, etc. Restoration of the esophageal conduit can be performed using gastric or colon interposition, radial forearm free flap or jejunum free flap, etc. Recently, the advances of radiation therapy and chemotherapy will enable less extended resections with greater rates of laryngeal preservation. At initial presentation, up to 50％ to 70％ of patients will have advanced locoregional or distant disease with virtually no chance for cure. Patients with advanced but potentially resectable esophageal cancer are generally treated by surgery with some form of neoadjuvant chemotherapy, radiotherapy, or both, with 5-year survivals in the 20％ to 30％ range. So the significant adverse factors affecting survival should be taken into account to select the candidates for surgery.

• 정보학연구
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• 제6권1호
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• pp.49-63
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• 2003

21세기 들어 e-비즈니스의 확산과 더불어 인터넷이라는 개방형 커뮤니케이션구조를 기반으로하는 네트워크기술의 도약적 발전으로 인해 수많은 중개형 e-마켓플레이스들이 등장하였다. 하지만, 이와같은 중개형 e-마켓플레이스들을 통한 기업간 전자상거래를 규모가 예상과 달리 저조함에 따라 현재 인지도가 높은 사이트들조차도 사업을 정리하거나 전환하고 있는 실정이다. 본 연구에서는 기업내부 혹은 기업간 e-비즈니스의 핵심거래기반으로서 논의되어왔던 e-마켓플레이스를 기업에서의 정보기술활용이라는 역사적 관점에서 재조명해보았다. 이를 통해 기업의 e-비즈니스 거래기반으로서의 중개형 e-마켓플레이스들의 위상과 갖추어야 할 비즈니스적 특성을 제시하였다.

• Clinical Endoscopy
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• 제56권6호
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• pp.681-692
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• 2023

In general, gastroesophageal reflux disease (GERD) is diagnosed clinically based on typical symptoms and/or response to proton pump inhibitor treatment. Upper gastrointestinal endoscopy is reserved for patients presenting with alarm symptoms, such as dysphagia, odynophagia, significant weight loss, gastrointestinal bleeding, or anorexia; those who meet the criteria for Barrett's esophagus screening; those who report a lack or partial response to proton pump inhibitor treatment; and those with prior endoscopic or surgical anti-reflux interventions. Newer endoscopic techniques are primarily used to increase diagnostic yield and provide an alternative to medical or surgical treatment for GERD. The available endoscopic modalities for the diagnosis of GERD include conventional endoscopy with white-light imaging, high-resolution and high-magnification endoscopy, chromoendoscopy, image-enhanced endoscopy (narrow-band imaging, I- SCAN, flexible spectral imaging color enhancement, blue laser imaging, and linked color imaging), and confocal laser endomicroscopy. Endoscopic techniques for treating GERD include esophageal radiofrequency energy delivery/Stretta procedure, transoral incisionless fundoplication, and endoscopic full-thickness plication. Other novel techniques include anti-reflux mucosectomy, peroral endoscopic cardiac constriction, endoscopic submucosal dissection, and endoscopic band ligation. Currently, many of the new endoscopic techniques are not widely available, and their use is limited to centers of excellence.

• Journal of Gastric Cancer
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• 제8권4호
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• pp.210-216
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• 2008

목적: 위식도접합부선암의 임상병리학적 특성은 서구와 아시아 간의 많은 차이를 보인다고 알려져 있다. 그러나, 한국의 경우 위식도접합부선암의 유병율이 매우 낮고 이에 대한 연구 또한 부족하다. 따라서 저자들은 우식도접합부선암의 Siewert 분류에 따른 임상병리학적 특성을 조사하여 서구와 다른 국내 위식도접합부선암의 특성을 연구하고자 하였다. 대상 및 방법: 2004년 5월부터 2008년 2월까지 본원에서 위암으로 수술을 시행 받은 환자들을 대상으로 수술소견 및 병리 사진을 토대로 Siewert 분류법에 따라 위식도접합부선암을 분류하고, 의무기록을 바탕으로 환자들의 임상병리학적 특성들을 조사하였다. 결과: 위식도접합부선암은 전체 1,778예 중 70예(3.9%)였다. Siewert 1형은 3예(4.3%)로 매우 드물었으며, 2형과 3형이 각각 30예(42.8%) 37예(52.8%)였다. 2형이 3형에 비하여 평균연령이 높았으나(64세 vs 59세, P=0.049), 남녀비에는 차이가 없었다. 2형과 3형간에 Barrett 식도의 발현 정도나 Lauren 분류의 차이는 없었으나, 저분화암의 빈도는 3형에서 유의하게 높았다(P=0.045). 68예(97.1%)에서 근치적 절제가 시행되었으며, 각 아형간에 TNM 병기의 차이는 없었다. 결론: 국내의 위식도접합부선암은 매우 드물며 특히 1형의 유병율이 매우 낮다. 본 연구에서 서구의 보고와 부분적으로 일치하지 않는 병리학적 특성을 보였다. 향후 보다 많은 환자들을 대상으로 한국인의 위식도접합부선암의 특성을 연구할 필요가 있다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권5호
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• pp.873-887
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• 2015

The springing response of a large blunt ship was considered to be influenced by a second order interaction between the incoming irregular wave and the blunt geometry of the forebody of the ship. Little efforts have been made to simulate this complicated fluid-structure interaction phenomenon under irregular waves considering the second order effect; hence, the above mentioned premise still remains unproven. In this paper, efforts were made to quantify the second order effect between the wave and vibrating flexible ship structure by analyzing the experimental data obtained through the model basin test of the scaled-segmented model of a large blunt ship. To achieve this goal, the measured vertical bending moment and the wave elevation time history were analyzed using a higher order spectral analysis technique, where the quadratic interaction between the excitation and response was captured by the cross bispectrum of two randomly oscillating variables. The nonlinear response of the vibrating hull was expressed in terms of a quadratic Volterra series assuming that the wave excitation is Gaussian. The Volterra series was then orthogonalized using Barrett's procedure to remove the interference between the kernels of different orders. Both the linear and quadratic transfer functions of the given system were then derived based on a Fourier transform of the orthogonalized Volterra series. Finally, the response was decomposed into a linear and quadratic part to determine the contribution of the second order effect using the obtained linear and quadratic transfer functions of the system, combined with the given wave spectrum used in the experiment. The contribution of the second order effect on the springing response of the analyzed ship was almost comparable to the linear one in terms of its peak power near the resonance frequency.

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1437-1443
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• 2018

In this work, $SnO_2$ modified with reduced graphene oxide (rGO) and carbon nanotubes (CNTs) separately and combined sensitized by using the co-precipitation method and their sensing behavior toward ethanol vapor at room temperature were investigated. An interdigitated electrode (IDE) gold substrate is very expensive compared to a fluorine doped tin oxide (FTO) substrate; hence, we used the latter to reduce the fabrication cost. The structure and the morphology of the studied materials were characterized by using differential thermal analyses (DTA) and thermogravimetric analysis (TGA), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller surface area and Barrett-Joyner-Halenda (BJH) pore size measurements. The studied composites were subjected to ethanol in its gas phase at concentrations from 10 to 200 ppm. The present composites showed high-performance sensitivity for many reasons: the incorporation of $SnO_2$ and CNTs which prevents the agglomeration of rGO sheets, the formation of a 3D mesopourus structure and an increase in the surface area. The decoration with rGO and CNTs led to more active sites, such as vacancies, which increased the adsorption of ethanol gas. In addition, the mesopore structure and the nano size of the $SnO_2$ particles allowed an efficient diffusion of gases to the active sites. Based on these results, the present composites should be considered as efficient and low-cost sensors for alcohol.

• Journal of Digestive Cancer Research
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• 제4권1호
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• pp.1-9
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• 2016

The abundance of multi-drug resistance ATPase binding cassette and deranged self-renewal pathways shown in cancer stem cells (CSCs) played a crucial role in tumorigenesis, tumor resistance, tumor recurrence, and tumor metastasis. Therefore, elucidation of CSCs biology can improve diagnosis, enable targeted treatment, and guide the follow up of GI cancer patients. In order to achieve chemoquiescence, seizing cancer through complete ablation of CSCs, CSCs are rational targets for the design of interventions that will enhance responsiveness to traditional therapeutic strategies and contribute in the prevention of local recurrence as well as metastasis. However, current cancer treatment strategies fail to either detect or differentiate the CSCs from their non-tumorigenic progenies mostly due to the absence of specific biomarkers and potent agents to kill CSCs. Recent advances in knowledge of CSCs enable to produce several candidates to ablate CSCs in gastrointestinal (GI) cancers, especially cancers originated from inflammation-driven mutagenesis such as Barrett's esophagus (BE), Helicobacter pylori-associated gastric cancer, and colitis-associated cancer (CAC). Our research teams elucidated through revisiting old drugs that proton pump inhibitor (PPI) and potassium competitive acid blocker (p-CAB) beyond authentic acid suppression, chloroquine for autophage inhibition, sonic hedgehog (SHH) inhibitors, and Wnt/β-catenin/NOTCH inhibitor can ablate CSCs specifically and efficiently. Furthermore, nanoformulations of these molecules could provide an additional advantage for more selective targeting of the pathways existing in CSCs just like current molecular targeted therapeutics and sustained action, while normal stem cells intact. In this review article, the novel approach specifically to ablate CSCs existing in GI cancers will be introduced with the introduction of explored mode of action.