• Journal of Gastric Cancer
• /
• v.15 no.1
• /
• pp.29-38
• /
• 2015

Purpose: Before expanding our indications for laparoscopic gastrectomy to advanced gastric cancer and adopting reduced port laparoscopic gastrectomy, we analyzed and audited the outcomes of laparoscopy-assisted distal gastrectomy (LADG) for adenocarcinoma; this was done during the adoptive period at our institution through the comparative analysis of short-term surgical outcomes and learning curves (LCs) of two surgeons with different careers. Materials and Methods: A detailed comparative analysis of the LCs and surgical outcomes was done for the respective first 95 and 111 LADGs performed by two surgeons between July, 2006 and June, 2011. The LCs were fitted by using the non-linear ordinary least squares estimation method. Results: The postoperative morbidity and mortality rates were 14.6% and 0.0%, respectively, and there was no significant difference in the morbidity rates (12.6% vs. 16.2%, P=0.467). More than 25 lymph nodes were retrieved by each surgeon during LADG procedures. The LCs of both surgeons were distinct. In this study, a stable plateau of the LC was not achieved by both surgeons even after performing 90 LADGs. Conclusions: Regardless of the experience with gastrectomy or laparoscopic surgery for other organs, or the age of surgeon, the outcome was quite acceptable; the learning process differ according to the surgeon's experience and individual characteristics.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.4
• /
• pp.135-143
• /
• 2005

This paper presents a case history of a geosynthetics-reinforced segmental retaining wall, which collapsed during a severe rainfall immediately after the completion of the wall construction. In an attempt to identify possible causes for the collapse, a comprehensive investigation was carried out including physical and strength tests on the backfill, stability analyses on the as-built design based on the current design approaches, and slope stability analyses with pore pressure consideration. The investigation revealed that the inappropriate as-built design and the bad-quality backfill were mainly responsible for the collapse. This paper describes the site condition including wall design, details of the results of investigation and finally, lessons learned. Practical significance of the findings from this study is also discussed.

• Journal of the Korean Society of Safety
• /
• v.35 no.4
• /
• pp.84-91
• /
• 2020

The Korean nuclear industry developed the SPACE (Safety and Performance Analysis Code for nuclear power plants) code and this code adpots two-phase flows, two-fluid, three-field models which are comprised of gas, continuous liquid and droplet fields and has a capability to simulate three-dimensional model. According to the revised law by the Nuclear Safety and Security Commission (NSSC) in Korea, the multiple failure accidents that must be considered for accident management plan of nuclear power plant was determined based on the lessons learned from the Fukushima accident. Generally, to improve the reliability of the calculation results of a safety analysis code, verification work for separate and integral effect experiments is required. In this reason, the goal of this work is to verify calculation capability of SPACE code for multiple failure accident. For this purpose, it was selected the experiment which was conducted to simulate a Multiple Steam Generator Tube Rupture(MSGTR) accident with Passive Auxiliary Feedwater System(PAFS) operation by Korea Atomic Energy Research Institute (KAERI) and focused that the comparison between the experiment results and code calculation results to verify the performance of the SPACE code. The MSGR accident has a unique feature of the penetration of the barrier between the Reactor Coolant System (RCS) and the secondary system resulting from multiple failure of steam generator U-tubes. The PAFS is one of the advanced safety features with passive cooling system to replace a conventional active auxiliary feedwater system. This system is passively capable of condensing steam generated in steam generator and feeding the condensed water to the steam generator by gravity. As the results of overall system transient response using SPACE code showed similar trends with the experimental results such as the system pressure, mass flow rate, and collapsed water level in component. In conclusion, it could be concluded that the SPACE code has sufficient capability to simulate a MSGTR accident.

• Nuclear Engineering and Technology
• /
• v.53 no.10
• /
• pp.3236-3246
• /
• 2021

Lessons learned from the Fukushima Daiichi nuclear power plant accident directed that multiple failures should be considered more seriously rather than single failure in the licensing bases and safety cases because attempts to take accident management measures could be unsuccessful under the high radiation environment aggravated by multiple failures, such as complete loss of electric power, uncontrollable loss of coolant inventory, failure of essential safety function recovery. In the case of the complete loss of electric power called station blackout (SBO), if there is no mitigation action for recovering safety functions, the reactor core would be overheated, and severe fuel damage could be anticipated due to the failure of the active heat sink. In such a transient condition at CANDU-6 plants, the seal failure of the primary heat transport (PHT) pumps can facilitate a consequent increase in the fuel sheath temperature and eventually lead to degradation of the fuel integrity. Therefore, it is necessary to specify the regulatory guidelines for multiple failures on a licensing basis so that licensees should prepare the accident management measures to prevent or mitigate accident conditions. In order to explore the efficiency of implementing accident management strategies for CANDU-6 plants, this study proposed a realistic accident analysis approach on the SBO transient with multiple-failure sequences such as seal failure of PHT pumps without operator's recovery actions. In this regard, a comparative study for two PHT pump seal failure modes with and without coolant seal leakage was conducted using a best-estimate code to precisely investigate the behaviors of thermal-hydraulic parameters during transient conditions. Moreover, a sensitivity analysis for different PHT pump seal leakage rates was also carried out to examine the effect of leakage rate on the system responses. This study is expected to provide the technical bases to the accident management strategy for unmitigated transient conditions with multiple failures.

• Journal of the Korean Society of Safety
• /
• v.37 no.5
• /
• pp.80-88
• /
• 2022

The Korean nuclear industry had developed the SPACE (Safety and Performance Analysis Code for nuclear power plants) code, which adopts a two-fluid, three-field model that is comprised of gas, continuous liquid and droplet fields and has the capability to simulate three-dimensional models. According to the revised law by the Nuclear Safety and Security Commission (NSSC) in Korea, the multiple failure accidents that must be considered for the accident management plan of a nuclear power plant was determined based on the lessons learned from the Fukushima accident. Generally, to improve the reliability of the calculation results of a safety analysis code, verification is required for the separate and integral effect experiments. Therefore, the goal of this work is to verify the calculation capability of the SPACE code for multiple failure accidents. For this purpose, an experiment was conducted to simulate a Control Element Drive Mechanism (CEDM) break with a safety injection failure using the ATLAS test facility, which is operated by Korea Atomic Energy Research Institute (KAERI). This experiment focused on the comparison between the experiment results and code calculation results to verify the performance of the SPACE code. The results of the overall system transient response using the SPACE code showed similar trends with the experimental results for parameters such as the system pressure, mass flow rate, and collapsed water level in component. In conclusion, it can be concluded that the SPACE code has sufficient capability to simulate a CEDM break with a safety injection failure accident.

• Information Systems Review
• /
• v.20 no.1
• /
• pp.81-98
• /
• 2018

ERP supports the automation and integration of business processes of enterprises and records voluminous data about the business activities of enterprises. The academe and business enterprises are focusing on process mining, which improves the performance of business processes and strengthens compliance. However, these studies focused on analysis of the business process of large companies, which adopts foreign ERP, such as SAP ERP or Oracle ERP. In comparison with foreign ERP, domestic ERP lags behind in terms of logging and managing of event data. Therefore, the application of process mining to domestic ERP is a challenging task. The present study aims to analyze domestic ERP based on process mining to overcome this challenge. This study discusses the lessons learned from a case study in a Korean cosmetics manufacturing company. Our results are expected to strengthen the competitiveness of Korean small and medium-sized enterprises that adopt domestic ERP and realize the outcomes of the large investment of the Korean government on the ERP implementation of enterprises.

• Communications of Mathematical Education
• /
• v.27 no.3
• /
• pp.283-299
• /
• 2013

Mathematics textbooks based on storytelling in elementary schools started to apply a new method of teaching math to the first and second grade students from this year. By surveying the actual responses of both in-service and pre-service teachers, this study aimed to find out critical opinions to assist future math teachers. The survey was conducted among 124 in-service teachers and 112 pre-service teachers, asking what they needed for the understanding of the storytelling theory and for the preparation of actual lessons. After analyzing data, we concluded that in-service teachers have more positive opinion about the efficiency of teaching and learning mathematics based on storytelling, but more negative opinion about the appropriateness of storytelling as a means for teaching and learning mathematics than the pre-service teachers in elementary school. The in-service elementary teachers also want to have well-organized teaching resources for storytelling and development. Through a lot of training, more and more creative ways of applying the storytelling method can be learned and concrete presentations of real lessons need to be shared. Approximately 87% of pre-service teachers believe the storytelling method is a necessity in teaching math.

• Journal of Energy Engineering
• /
• v.25 no.1
• /
• pp.43-47
• /
• 2016

KHNP CRI has developed APR+ nuclear power plant since 2007, which is GEN III+ model with 1500 MWe capacity. To develop safer nuclear power plant than APR1400, we investigated advanced design features of ALWR being constructed in Korea and being developed/constructed in foreign countries. We applied the advanced design features and lessons learned from Fukushima accident to develop APR+ standard design suitable for both domestic construction and overseas construction business. One economic assessments have performed during safety design improvement phase(2013.1 ~ 2015.12) of APR+. The result of the economic analysis for APR+ safety inhancement design showed that APR+ N-th plant is about 39.2% more economical than coal-fired 1,000MW power plant. Also APR+ plant is more cost advantage over foreign advanced nation ALWRs.

• Communications of Mathematical Education
• /
• v.25 no.1
• /
• pp.119-145
• /
• 2011

We study on the Connected Mathematics Project(CMP), one of the American mathematics education reform projects which have been promoted since the 1990s, so that we can provide some suggestions for the recent research of developing the 2009 Korean Mathematics Curriculum. In this paper, we examine the background of the CMP, the controversies over the textbooks [CMP1 textbooks] developed by CMP[CMP1] implemented from 1991 till 1996, and the curriculum of the CMP[CMP2] revised from CMP1 and carried from 2000 till 2006. Through the literature study, we can see that the CMP2 curriculum has reflected some of those controversies of the CMP1 textbooks by introducing procedures for students' acquiring basic skills, reducing the number of lessons and the contents supposed to be learned in each lesson, putting more stress on algebra and adding data analysis contents more.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.398-401
• /
• 2003

Along with rapid changes and increasing competitions of the global market, a country with advanced technology can gain competitiveness edges. The Korean government recently announced 'Strategic Plan for the Next Generation Driving Forces Industry' in order to respond this global challenges. However, it appears that the construction industry has been put out from the discussions. It can be argued that considering the size and contributions of the industry to the national economy, driving engines for the industry should be considered and identified. The objective of this paper is to propose the criteria of driving engines for the construction industry based on the analysis of the common characteristics of 6T industries' driving forces as recently announced.