• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.150-155
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• 1997

Modelling and Simulation of the activation process for the myocardium is meaningful to understand special excitation conduction system in the heart and to study cardiac functions. In this paper, we propose two dimensional cellular automata model for the activation process of the myocardium and simulated by means of discrete time and discrete event algorithm. In the model, cells are classified into anatomically similar characteristic parts of heart; SA node, internodal tracks, AV node, His bundle, bundle branch and four layers of the ventricular muscle, each of which has a set of cells with preassigned properties, that is, activation time, refractory duration and conduction time between neighbor cell. Each cell in this model has state variables to represent the state of the cell and has some simple state transition rules to change values of state variables executed by state transition function. Simulation results are as follows. First, simulation of the normal and abnormal activation process for the myocardium has been done with discrete time and discrete event formalism. Next, we show that the simulation results of discrete time and discrete event cell space model is the same. Finally, we compare the simulation time of discrete event myocardium model with discrete time myocardium models and show that the discrete event myocardium model spends much less simulation time than discrete time myocardium model and conclude the discrete event simulation method Is excellent in the simulation time aspect if the interval deviation of event time is large.

• Journal of Gastric Cancer
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• 제19권1호
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• pp.102-110
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• 2019

Purpose: Despite an increased acceptance of laparoscopic gastrectomy (LG) in early gastric cancer (EGC), there is insufficient evidence for its oncological safety in advanced gastric cancer (AGC). This is a prospective phase II clinical trial to evaluate the feasibility of LG with D2 lymph node dissection (LND) in AGC. Materials and Methods: The primary endpoint was set as 3-year disease-free survival (DFS). The eligibility criteria were as follows: 20-80 years of age, cT2N0-cT4aN3, American Society of Anesthesiologists score of 3 or less, and no other malignancy. Patients were enrolled in this single-arm study between November 2008 and May 2012. Exclusion criteria included cT4b or M1, or having final pathologic results as EGC. All patients underwent D2 lymphadenectomy. Three-year DFS rates were estimated by the Kaplan-Meier method. Results: A total of 157 patients were enrolled. The overall local complication rate was 10.2%. Conversion to open surgery occurred in 11 patients (7.0%). The mean follow-up period was $55.0{\pm}20.4months$ (1-81 months). The cumulative 3-year DFS rates were 76.3% for all stages, and 100%, 89.3%, 100%, 88.0%, 71.4%, and 35.3% for stage IB, IIA, IIB, IIIA, IIIB, and IIIC, respectively. Recurrence was observed in 37 patients (23.6%), including hematogenous (n=6), peritoneal (n=13), locoregional (n=1), distant node (n=8), and mixed recurrence (n=9). Conclusions: In addition to being technically feasible for treatment of AGC in terms of morbidity, LG with D2 LND for locally advanced gastric cancer showed acceptable 3-year DFS outcomes.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.581-584
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• 2004

Currently, there are many subscriber access networks: PSTN, ADSL, Cellular Network, IMT200 and so on. To these service providers that provide above network service, it is important that they authenticate and authorize legal subscribers and account for their usage. At present, There exist the several protocols that Support AAA(Authentication, Authorization and Accounting) service : RADIUS, Diameter, TACACS+. Nowadays, RADIUS has used for AAA service widely. It has been extended to support other access network environment. So, we extend RADIUS to support environment of Mobile IPv6. Mobile IPv6 uses IPsec as a security mechanism, basically. But, IPsec is a heavy security technology for small, portable, mobile device. Especially, it is serious at IKE, the subset of IPsec. IKE is a key distribution protocol that distributes the key to the endpoints of IPsec. In t:lis paper, we extend RADIUS to support environment of Mobile IPv6 and simplify the IKE phase of IPsec by AAA system distributing the keys by using its security communication channel. Namely, we propose the key distribution method for IPsec SA establishment between mobile node and home agent. The suggested method was anticipated to be effective at low-power, low computing deyice. Finally, end users feel the faster authentication.

• 대한전기학회논문지:전력기술부문A
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• 제49권7호
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• pp.313-322
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• 2000

This paper presents optimal placement of minimal set of Phasor Measurement Units (PMU's) and observability analysis of the network with PMU's. In order to find a observable system, a symbolic method which directly assigns an appropriate symbol for measurement or pseudo-measurement to every entry of node-branch incidence matrix is proposed. It is much simpler and easier to analyze the observability of the network with PMU's than the conventional ones. For the optimal PMU placement problem, two approaches which are based on a modified Simulated-Annealing (SA) method and a Direct Combination method are proposed. Some case studies with IEEE sample system are made to show the performance of the proposed methods are almost alike and more effective than the conventional simulated-annealing method. It is also shown that the Direct Combination method is more effective than the modified simulated-annealing one in the sense of computation burden. The results of this study showed also that the accuracy of power system estimation and system observability can be improved the proposed PMU placements.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2000년도 추계학술대회 논문집
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• pp.81-87
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• 2000

Beat-to-beat changes in heart period (heart period variability, HPV) are mediated by fluctuations in autonomic activity. Spectral analysis is used to quantify such fluctuations in the range of 0.15-0.40 Hz (high frequency, HF), which are influenced primarily by parasympathetic factors. These fluctuations are often referred to as RSA (respiratory sinus arrhythmia), the physiological phenomenon extracted by spectral analysis and other methods including histograms of heart rate ( HR), deviations of HR etc. Respiratory sinus arrhythmia indexing with peak-to-valley method suggested by Grossman et at., (1981) yields a simple range statistic and is quantified on breath-by-breath basis, thus being quite sensitive and less dependent on recording time as compared to spectral analysis. It is strongly recommended to use at least 1 min epoch to asses HF component of HPV and at least 2 min fer low frequency (LF) of HPV and even 5 min far valid clinical assessment. Peak-to-valley statistic is limited to RSA index only, but has its pragmatic advantages. Most important is possibility of its application far relatively small epoch analysis. We used short periods (20,30, 40 sec only) and off-line analysis of RSA using ECG and respiration curve this method of assessment and proved that this method is more practically effective. The RSA index was not so far dependent on respiration pattern differences and reflected actual vagal control of HR and were accompanied by low HR under some high stress conditions and in an aversive affective visual stimulation experiments. Another factor that might modulate cardiac chronotropic response is the interaction of sympathetic and parasympathetic inputs on sino-atrial (SA) node level, because responses to vagal influences are known to be proportional to ongoing sympathetic activity, that is so called accentuated antagonism. Since sympathetic outflow (increment of influences on SA) under negative emotions or stress was high in almost all physiological responses, vagal effects on HR could be therefore potentiated, leading to masking of output cardiac response seen in HPV, In the case of moderate sympathetic activation, on the other hand, autonomic interactions in cardiac control appear to be minimal. Thus RSA index appears to be an effective alternative method to assess and measure spectral HPV.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.772-776
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• 2004

This paper proposes an interference avoidance approach for Constraint-Based Routing (CBR) algorithm in the Multi-Protocol Label Switching (MPLS) network. The MPLS network itself has a capability of integrating among any layer-3 protocols and any layer-2 protocols of the OSI model. It is based on the label switching technology, which is fast and flexible switching technique using pre-defined Label Switching Paths (LSPs). The MPLS network is a solution for the Traffic Engineering(TE), Quality of Service (QoS), Virtual Private Network (VPN), and Constraint-Based Routing (CBR) issues. According to the MPLS CBR, routing performance requirements are capability for on-line routing, high network throughput, high network utilization, high network scalability, fast rerouting performance, low percentage of call-setup request blocking, and low calculation complexity. There are many previously proposed algorithms such as minimum hop (MH) algorithm, widest shortest path (WSP) algorithm, and minimum interference routing algorithm (MIRA). The MIRA algorithm is currently seemed to be the best solution for the MPLS routing problem in case of selecting a path with minimum interference level. It achieves lower call-setup request blocking, lower interference level, higher network utilization and higher network throughput. However, it suffers from routing calculation complexity which makes it difficult to real task implementation. In this paper, there are three objectives for routing algorithm design, which are minimizing interference levels with other source-destination node pairs, minimizing resource usage by selecting a minimum hop path first, and reducing calculation complexity. The proposed CBR algorithm is based on power factor calculation of total amount of possible path per link and the residual bandwidth in the network. A path with high power factor should be considered as minimum interference path and should be selected for path setup. With the proposed algorithm, all of the three objectives are attained and the approach of selection of a high power factor path could minimize interference level among all source-destination node pairs. The approach of selection of a shortest path from many equal power factor paths approach could minimize the usage of network resource. Then the network has higher resource reservation for future call-setup request. Moreover, the calculation of possible path per link (or interference level indicator) is run only whenever the network topology has been changed. Hence, this approach could reduce routing calculation complexity. The simulation results show that the proposed algorithm has good performance over high network utilization, low call-setup blocking percentage and low routing computation complexity.

• 대한조선학회논문집
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• 제32권1호
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• pp.42-57
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• 1995

자유표면의 유동문제는 저항추진성능과 내항성능이 우수한 선박과 파랑중 작업성능이 우수한 해양구조물의 설계와 관련되어 조선해양공학분야에서 지속적으로 관심의 대상이 되어온 연구분야이다. 본 논문에서는 선체주위 유동을 정확하고 효율적으로 해석하기 위한 3차원 수치해법의 개발을 목적으로 하였다. 수치해법으로 경계요소법을 사용하였으며, 그린함수는 간단한 랜킨소오스를 사용하였다. 전 경계요소면은 8점 경계요소로 표시하여 기하학적 특성을 정밀하게 반영하고자 하였다. 자유표면에서 속도포텐셜의 변화를 정규화된 8점 경계요소에서 이중 2차 스플라인함수(bi-quadratic spline function)로 표시함으로써 자유표면에서의 수치감쇠 및 분산오차를 개선하였다. 한편 물체표면에서의 물리량은 8점 경계요소의 특성을 살려 이중 2차 다항식(bi-quadratic function)으로 근사하였다. 이와같이 계산영역에 따라 해의 특성에 부합하는 수치방법을 채택함으로써 수치해의 정확성과 효율성이 향상되도록 하였다. 개발한 수치해법의 효능을 검증하기 위해 계산예로서 정상유동 및 비정상유동의 경우 Neumann-Kelvin문제를 다루었다. 본 방법에 의한 몰수 타원체 및 Series 60선에 대한 조파저항 계산결과는 적은 파넬수를 사용하고도 기존의 계산치는 물론 실험치와 좋은 일치를 보였다. 변형된 Wigley선형에 대한 동유체력 계산결과도 기존의 실험치 및 계산치와 비교적 잘 일치하였다. 비정상 유동의 경우 랜킨소오스법에서 일반적으로 적용하는 상류방사조건은 무차원주파수가 1/4보다 큰 경우에만 유효하므로, 본 논문에서는 파동방정식 연산자를 이용하여 무차원주파수가 1/4보다 작은 경우에 적용할 수 있는 상류방사조건을 유도하였다. 수면하에서 전진하며 동요하는 소오스에 대하여 적용한 결과 본 논문에서 유도한 방사조건이 유효함을 입증하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제17권sup3호
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• pp.179-183
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• 2016

Breast cancer is the most prevalent type of cancer among women around the world, and mortality is primarily caused by micro-metastatic disease. The complex mechanisms of breast cancer invasion and metastasis are intrinsically related to the malignant cell type so that early detection of micro-metastases can help prolongation of survival for patient. The aim of the present research work was evaluation of the expression status of mammoglobin protein as a candidate molecular marker in the negative sentinel lymph node (SLN). Fifty tumor specimens, and 50 normal adjacent breast tissue samples from the same patients were selected on the basis of having more than 10% tumor content for RNA extraction from SLNs. Tumor samples and normal adjacent breast tissue were archived in the form of frozen fresh tissue in liquid nitrogen. Real-time PCR was performed on a Bioner life express gradient thermal cycler system. Mammoglobin gene overexpression in breast cancer metastasis was investigated. Single marker results were mammaglobin 66.7% and CK19 50.0%, with 58.3% for the two in combination. Due to improved outcome with at least 3 genes (83.3%), it seems, triple marker evaluation will be most likely useful for detecting micro-metastases instead of studying separate genes.

• Journal of Gastric Cancer
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• 제21권2호
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• pp.169-178
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• 2021

Purpose: The aim of this study was to investigate the oncologic safety and identify potential candidates for proximal gastrectomy (PG) in upper third advanced gastric cancer (AGC) and esophagogastric junction (EGJ) cancers. Materials and Methods: Among 5,665 patients who underwent gastrectomy for gastric adenocarcinoma between January 2011 and December 2017, 327 patients who underwent total gastrectomy with standard lymph node (LN) dissection for upper third AGC and Siewert type II EGJ cancers were enrolled. We analyzed the correlation between the metastatic rates of distal LNs (No. 4d, 5, 6, and 12a) around the lower part of the stomach and the clinicopathological characteristics. We identified subgroups with no metastasis to the distal LNs. Results: The metastatic rate of distal LNs in proximal AGC and Siewert type II EGJ cancers was 7.0% (23 of 327 patients). On multivariate analysis, pathological T stage (P=0.001), tumor size (P=0.043), and middle third invasion (P=0.003) were significantly associated with distal LN metastases. Pathological 'T2 stage' (n=88), or 'T3 stage with ≤5 cm tumor size' (n=87) showed no metastasis in distal LNs, regardless of middle third invasion. Pathological T3 stage with tumor size > 5 cm (n=61) and T4 stage (n=91) had metastasis in the distal LNs. Conclusions: In the upper third AGC and Siewert type II EGJ cancer, pathological T2 and small-sized T3 stage groups are possible candidates for PG in cases without distal LN metastasis. Further validation studies are required for clinical application.

• Tuberculosis and Respiratory Diseases
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• 제71권6호
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• pp.464-469
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• 2011

Adalimumab is a full human monoclonal antibody that inhibits tumor necrosis factor-alpha (TNF-${\alpha}$). This has recently been shown to be effective in the treatment of rheumatoid arthritis (RA), ankylosing spondylitis, and other conditions. Sacoidosis is known to be the target for adalimumab but we describe a patient who has developed sarcoidosis with lung involvement during adalimumab therapy for RA. A 48-year-old woman, who was treated with adalimumab for 5 months, was admitted because of chronic cough and both hilar lymphadenopathy on chest radiography. Chest computed tomography revealed the enlargement of multiple lymph nodes in the right supraclavicular, subcarinal, both hilar and right axillary area. She was diagnosed with sarcoidosis based on the biopsy of supraclavicular lymph node, skin and lung through video-associated thoracoscopic surgery, which was non-caseating epitheloid cell granuloma and excluded from a similar disease. She was treated for sarcoidosis with prednisolone and methotrexate instead of adalimumab.