• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.19 no.1
• /
• pp.52-59
• /
• 2023

The welding part of the valve needs immediate action when leakage occurs due to cracks or damage. In order to repair leakage of the welding part, the valve must be separated from the pipe or replaced with a new valve. However, it is difficult to remove the valve while operating the power plant. This study presents a method to remove leakage by precisely processing the gap between the clamp and the incision part within 0.1mm while installed in the pipe system. If the external leakage is removed using a clamp on the welding part without removing the valve during operation, the time and cost required for maintenance can be reduced.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.110-110
• /
• 2022

2011~2019년 평균 강수량은 100년 전(1912~1920) 보다 861mm 증가(7.4%)하였으며, 2020년 서울, 부산, 대전 등 대도시 지역에서 침수로 인한 인명피해가 발생하는 등 기후변화로 인한 강우량, 집중호우의 발생 빈도와 강우강도 증가 및 지속적인 도시침수로 인한 인명·재산 피해를 지속적으로 발생하고 있다. 이와 같이 도시침수는 단기간 집중호우에 의해 발생하고 좁은 범위에 발생하지만 건물, 인구 등 밀집도가 높은 지역에 발생하여 피해가 크게 발생한다. 또한 우수관 개선, 배수 펌프장 등 구조적인 대책만으로는 한계가 있으며, 예 경보 등 비구조적인 대책과 합께 이루어져야 한다. 이에 본 연구에서는 과거침수피해이력자료와 강우자료를 이용하여 해당 행정동에 대해 침수발생 한계강우량을 추정하였으며, 침수피해이력이 없는 행정동에 대해서는 유역특성과 한계강우량과의 관계를 이용하여 한계강우량을 예측하는 모델을 개발하였다. 3,344개 행정동에 대해 한계강우량을 추정하였으며, 이를 활용하여 2021년 침수 예·경보에 시범적용하였다. 6월~9월 까지 운영한 결과를 대상으로 강우자료와 비교하여 정확성을 검토하고 오차가 10% 이상인 행정동에 대해서는 개선하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2023.05a
• /
• pp.17-18
• /
• 2023

Since March 15, 2022, the korea coast guard has revised the qualification standards for VTSO so that they can take the VTSO recruitment test under the korea coast guard without boarding experience to diversify their recruitment routes. By this study, we looked into VTS working circumstances and reviewed important provisions about enactment and revision of VTS regulations and VTS certificate system so far to compare and analyze pros and cons of each control task performance method by illustrations which are occasions in both home and foreign control operation. And also, I suggest ways to improve VTSO task in future make a VTSO credential demonstration system settle down successfully.

• Journal of Digestive Cancer Research
• /
• v.5 no.1
• /
• pp.50-54
• /
• 2017

Pancreatic neuroendocrine tumors are rare pancreatic neoplasms comprising 1-2% of all pancreatic tumors and typically present high attenuating mass on arterial and venous phase images, due to their rich capillary network. A 70-year-old South Korean female visited our hospital presenting with jaundice and dark urine color. She had received an operation for treatment of small bowel perforation seven years ago. On physical examination, icteric sclera was observed but otherwise unremarkable. Laboratory tests were abnormal liver function test and suspected obstructive jaundice. Computed tomography revealed 4 cm sized cystic mass lesion with homogeneous low attenuation in the head of pancreas and distal common bile duct was compressed by the mass. During review of past medical records, we found that the mass was observed and measured about 1.7 cm seven years ago. To resolve obstructive jaundice, pylorus preserving pancreaticoduodenectomy was performed and diagnosed with well differentiated pancreatic neuroendocrine carcinoma with intermediate grade.

• Korean Journal of Childcare and Education
• /
• v.19 no.5
• /
• pp.65-79
• /
• 2023

Objective: The purpose of this study was to identify the importance and performance of the evaluation indicators of the childcare center evaluation system among childcare center staff and to find ways to improve the evaluation indicators of the childcare center evaluation system. Methods: A survey was conducted among 296 directors and teachers of childcare centers located in Busan and Gyeongnam. The collected data were analyzed using a paired sample t-test and an IPA analysis with SPSS 23.0 and Excel 2010. Results: There was a difference between the perceived importance and performance of childcare staff for the overall evaluation indicators, and significant differences were found in all areas and nine evaluation indicators except for "childcare environment and operation management". According to the IPA analysis, Health and Safety fell into quadrant 1, Staff into quadrant 2, and Child Care Process, Interaction, Child Care Environment, and Operations into quadrant 3. This distribution resulted in 6 indicators in quadrant 1, 4 in quadrant 2, 7 in quadrant 3, and 1 in quadrant 4. Conclusion/Implications: This study provides essential data for exploring ways to enhance the evaluation indicators of the childcare center evaluation system, with the goal of improving the quality of childcare services. Additionally, it offers policy implications.

• Korea Trade Review
• /
• v.45 no.6
• /
• pp.55-75
• /
• 2020

This study examines factors that influence organizational identification of employees who work for foreign multinational corporations in Korea. First, we test whether employee perceptions on leader-member exchange, trust in CEO, and career growth opportunity can influence their organizational identification. second, we also investigate moderation effects of employee perception on subsidiary level factors such as co-operation between the subsidiary and its HQ, firm reputation of the subsidiary, and opportunity to work overseas. 391 survey results from 350 subsidiaries of multinational corporations in Korea has been collected for this study. We found that leader-member exchange, trust in CEO and career growth opportunity had a positive effect on organizational identification of employees who work for foreign subsidiaries of multinational corporations in Korea. We also found partial support for the moderation effects of HQ-subsidiary interrelationship and opportunity to work overseas in the relationship between predictors and organizational identification. With this in mind, I hope this help to reconsider competitiveness of global companies in Korea by increasing organizational identification.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.6
• /
• pp.1291-1298
• /
• 2023

Surveillance reconnaissance sensor network is used for surveillance in wartime and area of operation. In this paper, we propose a target localization method using the detection signal strength of seismic sensors. Relay equipment calculates the target location using coordinate information and detection signal strength of the seismic sensors. Target localization error deviation due to environmental factors was minimized by subtracting the dynamic offset when calculating the target location. Field test shows improvement of target localization through reduction of errors. The average error was decreased to 3.62m. Up to 62% improved result was obtained compared to weighted centroid localization method.

• Journal of Drive and Control
• /
• v.20 no.4
• /
• pp.100-106
• /
• 2023

We developed a crawler-based driving platform that can perform harvesting, transportation, pest control, and rotary operation by equipping it with various implements, and analyzed its performance. This single platform was developed to perform as pepper harvester, peanut harvester, and transporter with a 46-kW engine. A simulation model was developed to study the specifications of the platform, and the accuracy was also analyzed. The absolute percentage error ranged from 0.2 to 5.9%, which made it possible to predict the platform performance using simulation model. In T-test, both torque and speed on field and asphalt showed a significant difference (1%). Driving torque required differed depending on the nature of the field, and the speeds also changed based on soil load. The developed platform has the advantage of being equipped with a variety of working tools, expected to be used to harvest root crops in the future.

• Journal of Drive and Control
• /
• v.20 no.4
• /
• pp.17-26
• /
• 2023

A forklift is an industrial vehicle that lifts or transports heavy objects using a hydraulically operated fork, and is equipped with an automatic transmission for the convenience of repetitive transportation, loading, and unloading work. The Transmission Control Unit (TCU) is a key component in charge of the shift control function of an automatic transmission. It consists of an electric circuit with an input/output signal interface function and firmware running on a microcontroller. To develop TCU firmware, the development process of shifting algorithm design, firmware programming, verification test, and performance improvement must be repeated. A simulator is a device that simulates a mechanical system having dynamic characteristics in real time and simulates various sensor signals installed in the system. The embedded transmission simulator is a simulator that is embedded in the TCU firmware. information related to the mechanical system that is necessary for TCU normal operation. In this study, an embedded transmission simulator applied to the originally developed forklift TCU firmware was designed and used to verify various forklift shift control algorithms.

• International Journal of Computer Science & Network Security
• /
• v.24 no.3
• /
• pp.182-188
• /
• 2024

Hardware components are an integral part of Hardware Define Radio (HDR) for seamless operations and optimal performance. On the other hand, Software Define Radio (SDR) is a program that does not rely on any hardware components for its performance. Both of the latter radio programmers utilize modulation functions to make their core components from signal processing viewpoint. The following paper concentrates on SDR based modulation and their performance under different modulations. The bit error rate (BER) of modulations such as PSK, QAM, and PSAM were used as indicators to test channel quality estimation in planar Rayleigh fading. Though it is not commonly used for channel fading, the method of the adder determines the regionally segmented channel fading. Thus, the estimation error of the channel change substantially reduces the performance of the signal, hence, proving to be an effective option. Moreover, this paper also elaborates that BER is calculated as a function of the sample size (signal length) with an average of 20 decibels. Consequently, the size of the results for different modulation schemes has been explored. The analytical results through derivations have been verified through computer simulation. The results focused on parameters of amplitude estimation error for 1dB reduction in the average signal-to-noise ratio, while the combined amplitude deviation estimation error results are obtained for a 3.5 dB reduction