• The Journal of Korea Robotics Society
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• v.12 no.1
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• pp.86-93
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• 2017

The Expanded Guide Circle (EGC) method has been originally proposed as the guidance navigation method for improving the efficiency of the remote operation using the sensory information. The previous algorithm is, however, concerned only for the omni-directional mobile robot, so it needs to suggest a suitable one for a mobile robot with non-holonomic constraints. The ego-kinematic transform is a method to map points of $R^2$ into the ego-kinematic space which implicitly represents non-holonomic constraints for admissible paths. Thus, robots with non-holonomic constraints in the ego-kinematic space can be considered as "free-flying object". In this paper, we propose an effective obstacle avoidance method for mobile robots with non-holonomic constraints by applying EGC method in the ego-kinematic space using the ego-kinematic transformation. This proposed method shows that it works better for non-holonomic mobile robots such as differential-drive robot than the original one. The simulation results show its effectiveness of performance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.160-168
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• 1995

Desmutagenicities against 2-amino-1-methyl-6-phenylimidazo[4, 5-b] pyridine(PhIP) and 2-amino-3, 8-dimethylimidazo[4, 5-f]quinoxaline(MelQx) of tea extracts (steamed green tea, roasted green tea, oolong tea and black tea) were investigated. All the fractions obtained from tea extracts showed strong desmutagenic activity against PhIP and MeIQx toward S. typhimurium TA 98 in the presence of the S-9 mix. The crude catechin fraction exhibited the strongest desmutagenic activity. Among these tea extracts, black tea especially exhibited the strongest desmutagenic activity and the activity was 70.9~91.0% against PhIP and 92.2~98.8% against MelQx at a concentration(0.5~1.0mg/plate) for drinking. The activity of authentic catechins of (-)-EGC, (-)-EGCg, (-)-ECg and (-)-EC were 79.5%, 60.2%, 46.1% and 43.5% against PhIP, and were 52.3%, 11.6%, 8.2% and 22.1% against MelQx by addition of 1.0mg/plate, respectively. The desmutagenic activity was supposedly due to the (-)-EGCg, (-)-EGC and (-)-EC in tea polyphenols, and the browning materials. The desmutagenicity was stronger when mutagens were preincubated with S-9 mix after reaciton with black tea extracts than when preincubated with them after reaction with S-9 mix. The desmutagenicity of tea extracts was rather expressed by reacting directly with mutagens than by deactivating the activated forms of mutagens.

• Journal of Gastric Cancer
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• v.21 no.1
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• pp.4-15
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• 2021

Recently, endoscopic screening systems have enabled the diagnosis of gastric cancer in the early stages. Early gastric cancer (EGC) is typically characterized by a shallow invasion depth and small size, which can hinder localization of EGC tumors during laparoscopic surgery. Here, we review nine recently reported tumor localization methods for the laparoscopic resection of EGCs. Preoperative dye or blood tattooing has the disadvantage of spreading. Preoperative 3-dimensional computed tomography reconstruction is not performed in real time during laparoscopic gastrectomy. Thus, they are considered to have a low accuracy. Intraoperative portable abdominal radiography and intraoperative laparoscopic ultrasonography methods can provide real-time feedback, but these methods require expertise, and it can be difficult to define the clips in some gastric regions. Despite a few limitations, intraoperative gastrofibroscopy provides real-time feedback with high accuracy. The detection system using an endoscopic magnetic marking clip, fluorescent clip, and radio-frequency identification detection system clip is considered highly accurate and provides real-time feedback; we expect a commercial version of this setup to be available in the near future. However, there is not yet an easy method for accurate real-time detection. We hope that improved devices will soon be developed and used in clinical settings.

• Clinical Endoscopy
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• v.55 no.2
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• pp.248-255
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• 2022

Background/Aims: Endoscopic submucosal dissection (ESD) is the preferred technique for treating early gastric cancer (EGC). However, very few studies have been conducted in South America. This study aimed to assess the efficacy and safety of ESD for EGC. Methods: We analyzed data from a prospective cohort from 2013 to 2020. A total of 152 superficial gastric neoplasms that fulfilled the absolute or expanded criteria for ESD were included. Outcomes were en bloc, R0, and curative resection rates, incidence of adverse events, and length of procedure. Results: The age of the enrolled patients was 68.4±11.3 years. The number of included patients based on the absolute and expanded indications was 150 and 2, respectively. En bloc, R0, and curative resections were achieved in 98.0%, 96.1%, and 89.5% of the cases, respectively. Bleeding and perforation were reported in 5.9% and 6.6% of the cases, respectively. Histopathological examination revealed low-grade dysplasia, high-grade dysplasia, well-differentiated adenocarcinoma, and poorly differentiated adenocarcinoma in 13, 20, 117, and 2 cases, respectively. Conclusions: Our study shows that ESD performed by properly trained endoscopists in reference centers is safe and effective, with comparable therapeutic outcomes to those reported in the Eastern series.

• Journal of Gastric Cancer
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• v.8 no.2
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• pp.70-78
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• 2008

Purpose: VEGF-C and VEGF-D are angiogenetic factors, and abnormal expression of E-cadherin hasa role in the progression of gastric carcinoma. The aim of this study was to evaluate the relationship between the expression of E-cadherin, VEGF-C and VEGF-D with the presence of lymph node metastases (LNM) using cytokeratin 18 in early gastric cancer (EGC). Materials and Methods: Immunohistochemical staining for E-cadherin, VEGF-C and VEGF-D was performed in 49 EGC patients from March 1997 to December 2002. To evaluate the real extent of LNM, 1,562 lymph nodes from 49 patients were re-examined with the use of cytokeratin 18. Results: Eleven (0.7%) LNM were newly found in 12.2% (n=6) of patients. The real LNM rate was 3.6% in mucosal invasive (m) cancer and 38.1% in submucosal invasive (sm). Stage migration was seen in three patients (6.1%). Abnormal expression of E-cadherin was detected in 36.7% of the patients and expression of VEGF-C and VEGF-D was detected in 16.3% and 36.7% of the patients, respectively. Abnormal expression of E-cadherin was significantly correlated with tumor differentiation (P=0.0103) and Lauren classification (P<0.0001). There was no positive relationship of VEGF-C and VEGF-D expression with the clinicopathological findings for EGC including LNM. However, the frequency of lymph node metastases was significantly higher in patients that demonstrated abnormal expression of E-cadherin with positive immunoreactivity of VEGF-C or VEGF-D (P=0.031). Conclusion: In present study, we could not demonstrate a relationship between the presence of LNM and expression of VEGF-C and VEGF-D in EGC. However, VEGF-C or VEGF-D expression, in addition to the abnormal expression of E-cadherin, was correlated with the real extent of LNM in EGC.

• Journal of Gastric Cancer
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• v.20 no.3
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• pp.277-289
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• 2020

Purpose: To evaluate the feasibility and safety of intracorporeal overlapping gastrogastrostomy between the proximal anterior wall and antrum posterior wall (PAAP; PAAP anastomosis) of the stomach in minimally invasive pylorus-preserving gastrectomy (PPG) for early gastric cancer (EGC). Materials and Methods: From December 2016 to December 2019, 17 patients underwent minimally invasive PPG with PAAP anastomosis for EGC in the high body and posterior wall of the stomach. Intraoperative gastroscopy was performed with the rotation maneuver during proximal transection. A longer antral cuff (>4-5 cm) was created for PAAP than for conventional PPG (≤3 cm) at the point where a safe distal margin and good vascular perfusion were secured. Because the posterior wall of the proximal remnant stomach was insufficient for intracorporeal anastomosis, the anterior wall was used to create an overlapping anastomosis with the posterior wall of the remnant antrum. The surgical and oncological outcomes were analyzed, and the stomach volume was measured in patients who completed the 6-month follow-up. The results were compared to those after conventional PPG (n=11 each). Results: PAAP anastomosis was successfully performed in 17 patients. The proximal and distal resection margins were 2.4±1.9 cm and 4.0±2.6 cm, respectively. No postoperative complications were observed during the 1-year follow-up esophagogastroduodenoscopy (n=10). The postoperative remnant stomach (n=11) was significantly larger with PAAP than with conventional PPG (225.6±118.3 vs. 99.1±63.2 mL; P=0.001). The stomach length from the anastomosis to the pylorus was 4.9±2.4 cm after PAAP. Conclusions: PAAP anastomosis is a feasible alternative for intracorporeal anastomosis in minimally invasive PPG for highly posteriorly located EGC.

• Journal of Gastric Cancer
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• v.1 no.3
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• pp.161-167
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• 2001

Purpose: Although gastric carcinomas occur throughout the world and the incidence is on the decrease, they remain the most common type of carcinoma in Korea. Significant advancements in the diagnostics and the surgical treatment of gastric carcinomas have been achieved during the last three decades. The present retrospective study was undertaken to investigate the chronological changes in the clinical features, including clinicopathological findings, operative treatment, and prognosis of gastric carcinomas. Materials and Methods: A total of 1973 patients with a primary gastric adenocarcinoma who had been treated surgically during the period from 1983 to 1998 at the Department of Surgery, Korea University College of Medicine, were divided into two groups to evaluate chronological changes: 1007 patients had been treated during the period from 1983 to 1992 (early period) and 966 patients during the period from 1993 to 1998 (late period). Chronological changes in age, sex, ratio of early gastric cancer (EGC), and resectability were analyzed in all 1973 cases. For the 1755 resected cases, we also studied the chronological changes in the clinicopathological and treatment factors between the early-period (n=894) and the late-period (n=867) groups. Results: There were significant differences between the two periods with regard to age and ratio of EGC: EGC was more frequent in the late period. Univariate analysis of resected cases showed that gross type, tumor size, depth of invasion, UICC stage, and histological type were statistically significant. The analysis of the treatment factors revealed that total gastrectomies and extended lymphadenectomies were more frequent during the late period. The number of lymph nodes dissected was $26.0\pm12.7$ in the early period and $33.4\pm14.1$ in the late period (p<0.01). The 5-year survival rate in all cases was $51.4\%$ in the early period and $55.9\%$ in the late period. The stage-related survival rates (UICC 4th Ed., 1987) in the early vs. the late periods were $92.9\%\;vs.\;95.5\%$ in stage IA, $82.1\%\;vs.\;91.1\%$ in stage IB, $76.5\%\;vs.\;73.1\%$ in stage II, $46.5\%\;vs.\;52.1\%$ in stage IIIA, $14.5\%\;vs.\;33.6\%$ in stage IIIB, and $2.8\%\;vs.\;8.8\%$ in stage IV. There was a statistically significant difference in survival between stage IIIB and IV. Conclusion: These results suggest that the differences in the clinicopathological findings are related primarily to the increased number of early gastric cancer cases in the late period and that the improved survival noted during the late period for in stage IIIB and IV cancers might be related to extended surgery.

• Korean Journal of Food Science and Technology
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• v.47 no.4
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• pp.419-424
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• 2015

The objective of this study was to investigate the physicochemical and antioxidant properties of a variety of commonly consumed commercial green tea. Green tea samples with the same commercial name produced at different regions were analyzed. High-grade tea samples showed higher values of lightness (L) and greenness (-a). Additionally, compared to other varieties of teas, high-grade tea samples showed higher levels of catechin, gallocatechin gallate (GCg), epicatechin gallate (ECg), theanine, and methylxanthines and a lower level of epigallocatechin (EGC). The antioxidant activity of green tea was also investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical assays. High-grade teas were observed to have higher antioxidant activities. The results of this study indicate that the catechin content, such as EGCg, GCg, and ECg levels, was found to positively influence the total antioxidant activity of green tea.

• Korean Journal of Plant Resources
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• v.23 no.4
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• pp.386-392
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• 2010

This study was done to measure the color and catechins contents in processed teas using the whole bands (400~2500 nm) with near-infrared spectroscopy(NIRS). The powder colors of 109 processed teas were measured with a colorimeter. The a/b ratios in Hunter color scale in processed teas accounted for about 98.9% of the variation in the fermentation degree(FD), indicating that the a/b ratio was a very useful trait for assessing fermentation degree. Also tea powders were scanned in the visible bands used with NIRSystem. The calibration equations for powder colors were developed using the regression method of modified partial least squares(MPLS) with the internal cross validation. The equations had low SECV (standard errors of cross-validation), and high $R^2$ (coefficient of determination in calibration) values with 0.996~1.00, indicating that the visible bands(400~700 nm) with NIRS could be used to rapidly measure the variables related to powder color and fermentation degree. Also another powders of 137 processed teas were scanned at 780~2500 nm bands in the reflectance mode. The calibration equations were developed using the regression method of MPLS with the internal cross validation. The equations had low SECV, and high $R^2$ (0.896~0.983) values, showing that NIRS could be used to rapidly discriminate the contents of EGC($R^2$=0.919), EC(0.896), EGCg(0.978), ECg(0.905) and total catechins(0.983) in processed teas with high precision and ease.

• Journal of Gastric Cancer
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• v.1 no.2
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• pp.83-91
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• 2001

Purpose: This study was to observe whether the apoptotic function of tumor-infiltrating lymphocytes (TIL) is induced in human gastric epithelial dysplasia and gastric adenocarcinoma according to the role of FasL expression. Materials and Methods: A total of 56 gastric epithelial dysplasia and gastric adenocarcinoma patients were enrolled in this study: 9 cases of gastric epithelial dysplasia, 18 cases of early gastric carcinomas (EGC) and 29 cases of advanced gastric carcinomas (AGC). Immunohistochemical staining was performed for FasL and CD45, and the terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) method was used to detect cell death in tumor-infiltrating lymphocytes. Results: 1) Positive reactions of FasL to neoplastic cells were $88.9\%$ (8/9) in gastric epithelial dysplasia, $83.3\%$ (15/18) in EGC, and $75.9\%$ (22/29) in AGC. 2) Expression of TIL was decreased in the FasL positive region and was increased in the FasL negative region, and significant expression of TIL was observed in the AGC group (P=0.001). 3) Expression of apoptotic TIL was very similar to the FasL expression, and $100\%$ expression was observed in gastric epithelial dysplasia group. 4) Expression of apoptotic TIL was increased in the FasL positive region and decreased in the FasL negative region, and significant apoptotic expression was observed in the gastric epithelial dysplasia and EGC groups (P=0.0420, P=0.0263, respectively). Conclusion: These results suggest that FasL is a prevalent mediator of immune privilege in epithelial dysplasia and cancer of the stomach.