• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.517-531
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• 2021

The water supply facilities of Korea have achieved a rapid growth, along with the other social infrastructures consisting a city, due to the phenomenon of urbanization according to economic development. Meanwhile, the level of water supply service demanded by consumer is also steadily getting higher in keeping with economic growth. However, as an adverse effect of rapid growth, the quantity of aged water supply pipes are increasing rapidly, Bursts caused by pipe aging brought about an enormous economic loss of about 6,161 billion won as of 2019. These problems are not only worsening water supply management, also increasing the regional gap in water supply services. The purpose of this study is to classify hazard evaluation indicators and to rank the water distribution network hazard by cluster using the TOPSIS method. In conclusion, in this study, the entropy-based multi-criteria decision-making methods was applied to rank the hazard management of the water distribution network, and the hazard management ranking for each cluster according to the water supply conditions of the county-level municipalities was determined according to the evaluation indicators of water outage, water leakage, and pipe aging. As such, the hazard ranking method proposed in this study can consider various factors that can impede the tap water supply service in the water distribution network from a macroscopic point of view, and it can be reflected in evaluating the degree of hazard management of the water distribution network from a preventive point of view. Also, it can be utilized in the implementation of the maintenance plan and water distribution network management project considering the equity of water supply service and the stability of service supply.

• Journal of Gastric Cancer
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• v.23 no.4
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• pp.523-534
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• 2023

Purpose: Intra-abdominal infection is a common postoperative complication of laparoscopic pylorus-preserving gastrectomies (PPGs). Many studies have reported that intra-abdominal infectious complications after gastrectomy adversely affect patient survival outcomes. To prevent gastric fluid leakage into the abdominal cavity, we developed a novel anastomosis method in which the stomach lumen is not opened (termed the non-opened clean end-to-end anastomosis method [NoCEAM]) and evaluated its feasibility. Materials and Methods: Subsequent to lymphadenectomy, the oral and anal resection lines were sutured using an intraoperative endoscope. After closing the stomach circumferentially with clips, the specimen was rolled outward like a "donut." We resected the specimen circumferentially using a linear stapler, and anastomosis was completed simultaneously. We examined the feasibility of this procedure ex vivo, using three porcine stomachs, and in vivo, using one pig. Subsequently, we applied the procedure to 13 consecutive patients with middle-third early gastric cancer utilizing laparotomic, laparoscopic, and robotic PPG. Results: NoCEAM was completed in all porcine models and human cases. In the human cases, the mean operation time (±standard deviation) was 279±51 minutes, and mean blood loss volume was 22±45 mL. The mean number of linear staples used was 5.06±0.76. None of the patients had complications, and all were discharged on the eighth postoperative. The serum total protein, serum albumin, and hemoglobin levels did not change significantly after surgery. Conclusions: NoCEAM is feasible and safe for performing totally laparoscopic or robotic PPG. It may reduce postoperative complications, such as intra-abdominal infections.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.3
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• pp.379-392
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• 2024

With the rapid increase in data, saving storage space and improving the efficiency of data transmission have become critical issues, making the research on the efficiency of data compression technologies increasingly important. Lossless algorithms can precisely restore original data but have limited compression ratios, whereas lossy algorithms provide higher compression rates at the expense of some data loss. There has been active research in data compression using deep learning-based algorithms, especially the autoencoder model. This study proposes a new side-channel analysis data compressor utilizing autoencoders. This compressor achieves higher compression rates than Deflate while maintaining the characteristics of side-channel data. The encoder, using locally connected layers, effectively preserves the temporal characteristics of side-channel data, and the decoder maintains fast decompression times with a multi-layer perceptron. Through correlation power analysis, the proposed compressor has been proven to compress data without losing the characteristics of side-channel data.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.27 no.1
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• pp.6-19
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• 2023

A systematic review was conducted in compliance with PRISMA statement standards to identify all studies reporting outcomes of laparoscopic resection of benign or malignant lesions located in caudate lobe of liver. Pooled outcome data were calculated using random-effects models. A total of 196 patients from 12 studies were included. Mean operative time, volume of intraoperative blood loss, and length of hospital stay were 225 minutes (95% confidence interval [CI], 181-269 minutes), 134 mL (95% CI, 85-184 mL), and 7 days (95% CI, 5-9 days), respectively. The pooled risk of need for intraoperative transfusion was 2% (95% CI, 0%-5%). It was 3% (95% CI, 1%-6%) for conversion to open surgery, 6% (95% CI, 0%-19%) for need for intra-abdominal drain, 1% (95% CI, 0%-3%) for postoperative mortality, 2% (95% CI, 0%-4%) for biliary leakage, 2% (95% CI, 0%-4%) for intra-abdominal abscess, 1% (95% CI, 0%-4%) for biliary stenosis, 1% (95% CI, 0%-3%) for postoperative bleeding, 1% (95% CI, 0%-4%) for pancreatic fistula, 2% (95% CI, 1%-5%) for pulmonary complications, 1% (95% CI, 0%-4%) for paralytic ileus, and 1% (95% CI, 0%-4%) for need for reoperation. Although the available evidence is limited, the findings of the current study might be utilized for hypothesis synthesis in future studies. They can be used to inform surgeons and patients about estimated risks of perioperative complications until a higher level of evidence is available.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.172-173
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• 2012

Currently GaN based LED is known to show high internal or external efficiency at low current range. However, this LED operation occurs at high current range and in this range, a significant performance degradation known as 'efficiency droop' occurs. Auger process, carrier leakage process, field effect due to lattice mismatch and thermal effects have been discussed as the causes of loss of efficiency, and these phenomena are major hindrance in LED performance. In order to investigate the main effects of efficiency loss and overcome such effects, it is essential to obtain relative proportion of measurements of internal quantum efficiency (IQE) and various radiative and nonradiative recombination processes. Also, it is very important to obtain radiative and non-radiative recombination times in LEDs. In this research, we measured the IQE of InGaN/GaN multiple quantum wells (MQWs) LEDs with PSS and Planar substrate using modified ABC equation, and investigated the physical mechanism behind by analyzing the emission energy, full-width half maximum (FWHM) of the emission spectra, and carrier recombination dynamic by time-resolved electroluminescence (TREL) measurement using pulse current generator. The LED layer structures were grown on a c-plane sapphire substrate and the active region consists of five 30 ${\AA}$ thick In0.15Ga0.85N QWs. The dimension of the fabricated LED chip was $800um{\times}300um$. Fig. 1. is shown external quantum efficiency (EQE) of both samples. Peak efficiency of LED with PSS is 92% and peak efficiency of LED with planar substrate is 82%. We also confirm that droop of PSS sample is slightly larger than planar substrate sample. Fig. 2 is shown that analysis of relation between IQE and decay time with increasing current using TREL method.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.113-118
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• 2016

In this paper, a read-in integrated circuit (RIIC) for IR scene projectors (IRSPs) adopting a sub-frame control technique is proposed, which minimizes the reduction of the apparent temperature of the IR images projected from IRSPs operating at a frame rate of 30 Hz. The proposed sub-frame control technique significantly reduces the amount of scene data loss on capacitors, which is caused by leakage currents flowing through MOSFET switches during holding periods, by dividing a unit frame into 8 sub-frames and refreshing the same scene data for each sub-frame. A current-drive RIIC was designed for the higher apparent temperature of IR radiated from the emitter, and it receives the scene data as a form of analog voltages from an external DAC. A prototype chip with a $64{\times}32$ RIIC array was fabricated using Magnachip/SKhynix $0.35{\mu}m$ 2-poly 4-metal CMOS process, and the measured maximum output data current is $230.3{\mu}A$. This amount of current ensures the projection of IR images whose maximum apparent temperature is $366.2^{\circ}C$ in the mid-wavelength IR (MWIR) when applied to a prototype emitter having a resistance of $15k{\Omega}$.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.762-774
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• 1984

A clinical analysis was performed on 49 cases of the benign esophageal diseases experienced at Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital during 7 year period from 1977 to 1983. Of 49 cases Of the benign esophageal diseases, there were 19 patients of esophageal stricture, 11 of achalasia, 6 of perforation, 3 of bronchoesophageal fistula, 3 of esophageal perforation, 3 of esophageal leiomyoma and one of esophageal foreign body. Twenty three patients were male and 26 were female. Ages ranged from 4 years to 74 years with the average age of 34.7 years. Of 19 patients of esophageal strictures, 7 patients were male and 12 were female and ages ranged from 6 years to 74 years with the average being 33.8 years. Causes of esophageal strictures were corrosive of esophageal strictures were dysphagia, vomiting, general weakness, weight loss and pain that order and developed on several different parts of esophagus. Operations were performed in 18 cases, of whom 7 patients were performed by esophagocologastrostomy, 4 gastrostomy, 4 esophagogastrostomy, 1 esophageal resection and esophagoesophagostomy, 1 esophagotomy and dilatation and 1 scar revision. Five patients had one or two complications; 2 anastomotic leakage, 1 wound infection, 1 localized empyema, 1 bilateral pneumothorax and 1 respiratory failure. One patient expired due to respiratory failure arising from aspiration pneumonia. The average age of achalasia patients was 33.1 years and symptom durations were from 2 months to 10 years with the average of 3.3 years. Main symptoms were dysphagia, vomiting, weight loss, pain and cough in that order. Modified Hellers myotomy was performed in 11 patients with one complication of restenosis. One patient was operated on by using longitudinal incision and transverse sutures with good result. Of 6 patient of esophageal diverticulum, 2 patients were traction diverticulum on the midesophagus, 2 were pulsion diverticulum on the midesophagus and 2 were pulsion diverticulum on the lower esophagus. Diverticulectomy was performed on 2 cases of traction diverticulum and esophagocardiomyotomy with or without diverticulectomy was erformed on 4 cases of pulsion diverticulum with good results. Of 5 patients of congenital bronchoesophageal fistula, the chief complaints were productive cough in 4 patients and hematemesis without respiratory symptoms in one patient. Two patients were operated on by using fistulectomy only and 3 by fistulectomy with pulmonary lobectomy. Of 3 patients of esophageal perforation, causes were foreign body ingestion, esophageal stricture after ECG and corrosive esophagitis. Two patient were operated on by using drainage and gastrostomy with symptomatic improvement but one patient died due to septic shock after thoracotomy. Three patients of esophageal leiomyoma were all male and 2 patients were operated on by using enucleation and one by distal esophagectomy with esophagogastrostomy. In one patient of esophageal foreign body, it was removed by esophagotomy through the right thoracotomy.

• Applied Microscopy
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• v.18 no.1
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• pp.92-102
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• 1988

The ototoxic effects of salicylate on the ultrastructure of spiral ganglion cells were examined. Sodium salicylate($50{\sim}60\/kg$ body weight, once a day for 7 days) were injected subcutaneously to $5{\sim}6$ week-old fifteen Sprague-Dawley rats. Animals were sacrificed 24 hours (group 1), 6 weeks (group 2) or 10 weeks (group 3) after the last injection. In group 1 animals, distention of membranous cisternae was found in the cytoplasm of ganglion cells, satellite cells and Schwann cells in which enlargement or multicystic cytosome formation of the mitochondria were shown. In group 2 animals, membranous cisternae became larger or fused to form larger vacuoles or cysts. Shrinkage of spiral ganglion cell cytoplasm and loosening of myelin sheath were seen. In group 3 animals, extensive swelling or loss of nerve fibers were shown along with the folding or partial loss of myelin sheath which caused leakage of ganglion cell cytoplasm. It was concluded that the ototoxicity of salicy-late caused the ultrastructral changes of the spiral ganglion cells which became more severe in group 2 and 3 animals. The possibility of retrograde degeneration following the sensory cell changes was suggested.

• Journal of the Korean Geotechnical Society
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• v.34 no.7
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• pp.17-27
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• 2018

Sinkholes have occurred in various places around the world and concerns about public safety have been raised in recent years. Particularly, a ground subsidence may occur due to a variety of conditions when developing underground spaces. Ground subsidence refers to the sinking of the Earth's surface caused by the loss of the soil constituting ground due to a certain artificial cause in the ground. Ground subsidence is induced by artificial causes such as the leakage of water supply/sewage pipes and groundwater disturbance, and it is different from a sinkhole, where the sinking of the Earth's surface is induced by the cavity formed due to the melting of limestone in the ground with limestone bedrock. In recent underground development in the urban areas of Korea, damages to surrounding buildings have frequently led to many difficulties with civil complaints and compensation issues, and the collapse of some buildings has resulted in the loss of lives and property. Accordingly, the central government has legislated the Special Act on Underground Safety Management, which will take effect from January 1, 2018. This law specifies an underground safety management system for securing underground safety, under which underground safety impact assessment is performed for projects involving underground excavation work that exceeds a certain size, and safety inspection is regularly performed for underground facilities and the surrounding ground. In this study, the contents of the special act on underground safety management are reviewed, and the direction of development of underground safety policy for preparing preemptive underground safety management preparation and response system is suggested.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.2
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• pp.104-110
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• 2019

In this paper, a complementary metal oxide semiconductor(CMOS) power amplifier(PA) integrated circuit operating in the 900 MHz band for long-term evolution(LTE) communication systems is presented. The output matching network based on a transformer was implemented on a printed circuit board for low loss. Simultaneously, to achieve high efficiency of the PA, the second harmonic impedances are controlled. The CMOS PA was fabricated using a $0.18{\mu}m$ CMOS process and measured using an LTE uplink signal with a bandwidth of 10 MHz and peak to average power ratio of 7.2 dB for verification. The implemented CMOS PA module exhibits a power gain of 24.4 dB, power-added efficiency of 34.2%, and an adjacent channel leakage ratio of -30.1 dBc at an average output power level of 24.3 dBm.