• Radiation Oncology Journal
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• v.11 no.1
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• pp.103-108
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• 1993

Among the patients with rectal cancer who entered Yonsei University Hospital for management from Jan. 1980 to Dec. 1990, we selected 23 subjects who were received surgical resection of tumor in rectum, and who proved to have liver metastasis during the diagnostic work-up, at the time of the operation, or within 3 months after starting definitive treatment. With those subjects, we investigated the role of radiation therapy by comparison of the treatment results of the patients without radiation therapy (S group) with those of the patients with radiation therapy to the primary site (S+R group). The local control rates of S group and S+R group were $64{\%}$ and $89{\%}$, and 2-year survival rates were $50{\%}$ and $78{\%}$, respectively. Although there was not statistically meaningful difference, local control rate and 2-year survival rate were higher in the group with radiation therapy to primary site than that without radiation therapy. The 2-year survival rates of the case with resection of the liver and the case without it were $63.6{\%}$ and $58.3{\%}$ respectively, which was not statistically significant. Also, the 2-year survival rate of the case with sustained local control was higher than that of the case with local failure, which was statistically significant ($76.5{\%}$ and $16.7{\%}$, p<0.005). From the above results, it is thought that radiation therapy to the primary site might improve the local control rate even in the patients with liver metastasis, which seems to be correlated to the higher survival rate.

• Wind and Structures
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• v.27 no.4
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• pp.223-234
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• 2018

In this study, a simplified three-dimensional calculation model is developed for the dynamic analysis of soil-pile group-supertall building systems excited by wind loads using the substructure method. Wind loads acting on a 300-m building in different wind directions and terrain conditions are obtained from synchronous pressure measurements conducted in a wind tunnel. The effects of soil-structure interaction (SSI) on the first natural frequency, wind-induced static displacement, root mean square (RMS) of displacement, and RMS of acceleration at the top of supertall buildings are analyzed. The findings demonstrate that with decreasing soil shear wave velocity, the first natural frequency decreases and the static displacement, RMS of displacement and RMS of acceleration increase. In addition, as soil material damping decreases, the RMS of displacement and the RMS of acceleration increase.

• KIEE International Transactions on Power Engineering
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• v.3A no.4
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• pp.206-213
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• 2003

The main purpose of this paper is to present a simulation model for assessing the impacts of a variable speed wind turbine (VSWT) on the distribution network and perform a simulation analysis of voltage profiles along the wind turbine installed feeder using the presented model. The modeled wind energy conversion system consists of a fixed pitch wind turbine, a synchronous generator, a rectifier and a voltage source inverter (VSI). Detailed study on the voltage impacts of a variable speed wind turbine is conducted in terms of steady state and dynamic behaviors. Various capacities and different modes of variable speed wind turbines are simulated and investigated. Case studies demonstrate how feeder voltages are influenced by capacity and control modes of wind turbines and changes in wind speed under different network conditions. Modeling and simulation analysis is based on PSCAD/EMTDC a software package.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1124-1136
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• 2017

Direct Power Control technique has become popular in the grid connected Voltage Source Converter (VSC) applications due to its simplicity, direct voltage vector selection and improved dynamic performance. In this paper, a direct method to determine the effect of voltage vector on the instantaneous active and reactive power variations is developed. An alternative Look Up Table is proposed which minimizes the commutations in the converter and results in minimum reactive power variation. The application of suggested table is established for Shunt Active Power Filter (SAPF) application. The Predictive Direct Power Control method, which minimizes apparent power variation, is further investigated to reduce commutations in converters. Both the methods are validated using 2 kVA laboratory prototype of Shunt Active Power Filters (SAPF).

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.82-88
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• 2017

This study proposes a new topology for the performance test of a valve consisting of a modular multilevel converter (MMC)-based static synchronous compensator (STATCOM). The conventional valve performance test equipment requires high-voltage AC source of several kV rating because the number of submodules to be tested in a valve should be at least six or eight. However, the power source of the proposed scheme is DC and not AC source. The DC power source voltage range of the proposed test circuit is from several volts to several tens of volts. Therefore, the size and cost for the performance test equipment can be reduced considerably compared with the conventional method. The proposed scheme satisfies the requirements of the IEC 62927 standard. Simulations are conducted for a valve of 50[MVA] MMC-based STATCOM. Experimental results with a scale-downed setup show the validity of the proposed performance test topology.

• Journal of Communications and Networks
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• v.5 no.1
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• pp.33-42
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• 2003

In this paper a two-stage maximum-likelihood (ML) detection structure for group detection in DS/CDMA systems is presented. The first stage of the receiver is a linear filter, aimed at suppressing the effect of the unwanted (i.e., out-of-grout) users' signals, while the second stage is a non-linear block, implementing a ML detection rule on the set of desired users signals. As to the linear stage, we consider both the decorrelating and the minimum mean square error approaches. Interestingly, the proposed detection structure turns out to be a generalization of Varanasi's group detector, to which it reduces when the system is synchronous, the signatures are linerly independent and the first stage of the receiver is a decorrelator. The issue of blind adaptive receiver implementation is also considered, and implementations of the proposed receiver based on the LMS algorithm, the RLS algorithm and subspace-tracking algorithms are presented. These adaptive receivers do not rely on any knowledge on the out-of group users' signals, and are thus particularly suited for rejection of out-of-cell interference in the base station. Simulation results confirm that the proposed structure achieves very satisfactory performance in comparison with previously derived receivers, as well as that the proposed blind adaptive algorithms achieve satisfactory performance.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4571-4575
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• 2012

Introduction and Purpose: The frequency of bilateral breast cancer is 1.4-11.0% among all breast cancers. It can present as synchronous (SC) or metachronous (MC). Data regarding clinical course of bilateral breast cancer are scarce. In this study, we therefore evaluated demographic, pathological and clinical characteristics, treatments and responses in bilateral breast cancer cases; making distinctions between metachronous-synchronous and comparing with historic one-sided data for the same parameters. Materials and Methods: One hundred fifty bilateral breast cancer cases from ten different centers between 2000 and 2011 were retrospectively scanned. Age of the cases, family history, menopausal status, pathological features, pathological stages, neoadjuvant, surgery, adjuvant and palliative chemotherapy/radiotherapy were examined in the context of the first and second occurrence and discussed with reference to the literature. Results: Metachronous and synchronous groups showed similar age, menopausal status, tumor type, HER2/neu expression; the family history tumor grade, tumor stage, ER-negativity rate, local and distant metastases rates, surgery, adjuvant chemotherapy application rates were identified as significantly different. Palliative chemotherapy response rate was greater in the metachronous group but median PFS rates did not differ between the groups. Conclusion: Although bilateral breast cancer is not frequent, MC breast cancer is different from SC breast cancer by having more advanced grade, stage, less ER expression, more frequent rates of local relapse and distant metastasis and better response to chemotherapy in case of relapse/metastasis.

• Journal of Gastric Cancer
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• v.4 no.4
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• pp.277-281
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• 2004

Early gastric cancer (EGC) is defined as a carcinoma confined to the mucosa or submucosa of the stomach, with or without lymph-node metastasis. Synchronous liver metastasis is 5. $12.8\%$ in advanced gastric cancer, but is very low in EGC. A 64-year-old woman was admitted to St. Vincent's Hospital with a complaint of epigastric pain. Gastrofiberscopic examination showed a polypoid mass on the gastric antrum. Abdominal computed tomography demonstrated an intraluminal polypoid mass in the gastric antrum, but no tumor mass in the liver. A laparotomy revealed a solitary liver metastasis, we performed a distal partial gastrectomy with a group-2 lymph-node dissection and resection of metastatic liver tumor. Histologic examination showed a tubular adenoma with a focal carcinomatous change, Which was confined to the gastric mucosa and to the metastatic adenocarcinoma in the liver. We present a case of early gastric mucosal cancer associated with synchronous liver metastasis, along with a review of the literature.

• Journal of Gastric Cancer
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• v.3 no.3
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• pp.139-144
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• 2003

Purpose: Because of an improving gastric cancer detection program and treatment methods, we can expect improved survival of patients with gastric cancer. Given the longer survival times, the chance of an occurrence of multiple primary malignant tumors other than stomach is increased in the same patients. The purpose of this study is to analyze the clinical characteristrics and the survival of patients with gastric cancer and other malignancies. Materials and Methods: A retrospective study of 3669 patients with gastric cancer observed at our department between January 1994 to December 2002 was conducted. Associated tumors were diagnosed using the Warren and Gates criteria, and included tumors that were not considered to be a metastasis, invasion, or recurrence of the gastric cancer. Results: Of all 3669 patients, $2.07\%$ (n=76) had primary tumors other than gastric cancer, $63\%$ of which were synchronous (n=48) and $37\%$ metachronous (n=28). The mean age of the study group was 64.9 (65.5 in males, 61.8 in females), and the male-to-female ratio was 4.8 : 1. The most common cancer associated with gastric cancer was a hepatocellular carcinoma ($23.7\%$), followed by colorectal cancer ($17.1\%$), esophageal cancer ($10.5\%$), breast cancer ($6.6\%$). Of the 45 patients who had undergone a resection, 14 were in stage I, 12 in stage II, 13 in stage III, and 6 in stage IV. No statistically significant differences were found between the synchronous and the metachronous groups with regard to age, sex ratio, differentiation, and stage. The 5-year survival rates of the metachronous and the resected patients were significantly higher than those of the synchronous and the non resected patients, respectively. Conclusion: Due to increasing length of the follow-up period for patients with gastric cancer, another malignancy may develop in other organs. Therefore, physicians should pay attention to detect other cancers early in these patients, and a surgical resection is recommended as the treatment of choice in the management of multiple primary cancer associated with gastric cancer.

• Proceedings of the KSRS Conference
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• v.1
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• pp.79-81
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• 2006

Geostationary ocean satellite, unlike other sun-synchronous polar-orbit satellites, will be able to take a picture of a large region several times a day (almost with every one hour interval). For geostationary satellite, the target region is fixed though the location of sun is changed always. Thus, the ocean signal of a given target point is largely dependent on time. In other words, the ocean signal detected by geostationary satellite sensor must translate to the signal of target when both sun and satellite are located in nadir, using another correction model. This correction is performed with a standardization of signal throughout relative geometric relationship among satellite - sun - target points. One signal value of a selected pixel point of the target region of Geostationary Ocean Colour Imager (GOCI) would be set up as a standard, and the ratio of all remained pixel point can be calculated. This relative ratio called bidirectional factor, the result of modelling of spatiotemporal variation of bidirectional factor is shown.