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Jung Youngrak,Cho Ara,Yang Seungjoon,Jeon Yutae,Bae Seong Hoon 대한청각학회 2022 Journal of Audiology & Otology Vol.26 No.1
Background and Objectives: Some reports propose an increased risk of otitis media and hearing impairment after total laryngectomy. However, the incidence of otitis media following laryngectomy and the mechanism remain unclear. This study aimed to identify the incidence and risk factors of otitis media after total laryngectomy.Subjects and Methods: This retrospective cohort study assessed 77 patients who underwent total laryngectomy from 2010 to 2020 in a tertiary referral center. Serial imaging studies (computed tomography [CT], magnetic resonance imaging, and positron emission tomography-CT) were used to assess otitis media.Results: The study enrolled 58 patients (mean age, 67.0±7.7 years; male, 56 [96.6%]); nine (15.5%) underwent a gastrostomy tube (four preoperatively and five postoperatively). Otitis media was confirmed in seven (12.1%) patients. Gastrostomy tube insertion was the only significant risk factor for otitis media (p=0.012). Of the nine patients who underwent gastrostomy tube insertion, four developed otitis media; all four had the procedure after laryngectomy.Conclusions: This study found an increased incidence of otitis media after total laryngectomy. Swallowing difficulties likely contribute to otitis media as it occurred more frequently in patients requiring postoperative gastrostomy tube insertion.
Efficient simultaneous production of biodiesel and glycerol carbonate via statistical optimization
Lee, Youngrak,Lee, Ja Hyun,Yang, Ho Jin,Jang, Min,Kim, Jung Rae,Byun, Eui-Hong,Lee, Jinwon,Na, Jeong-Geol,Kim, Seung Wook,Park, Chulhwan THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2017 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.51 No.-
<P><B>Abstract</B></P> <P>The purpose of this study was to simultaneously produce biodiesel and glycerol carbonate. Glycerol carbonate is a high-value material that could be obtained from glycerol. Response surface methodology was used to perform optimization of simultaneous enzymatic production of biodiesel and glycerol carbonate. Independent factors for optimization of simultaneous enzymatic production included enzyme concentration, a molar ratio of dimethyl carbonate to soybean oil, and reaction temperature. The levels of satisfaction with the production reaction model for biodiesel and glycerol carbonate were high, 0.994 and 1, respectively. The optimum condition for simultaneous production was 116.76g/L enzyme concentration, 9.27:1 molar ratio, and 52.56°C reaction temperature. Under the optimum condition, biodiesel 96.3% and glycerol carbonate 99.7% were produced at the same time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biodiesel and glycerol carbonate were simultaneously produced by the enzymatic process. </LI> <LI> RSM was used to optimize the production of biodiesel and glycerol carbonate. </LI> <LI> The optimum condition was 116.76g/L enzyme concentration, 9.27:1 molar ratio, and 52.56°C reaction temperature. </LI> <LI> Optimum production of biodiesel (96.3%) and glycerol carbonate (99.7%) yield was achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Lee, Youngrak,Kim, Sung Bong,Lee, Taek,Jang, Min,Shin, Ashley,Park, Si Jae,Kim, Jung Rae,Choi, Yoon-E,Na, Jeong-Geol,Park, Chulhwan Elsevier 2019 JOURNAL OF CLEANER PRODUCTION Vol.218 No.-
<P><B>Abstract</B></P> <P>A solvent-free co-production process for biodiesel and glycerol carbonate (GC) was developed based on enzyme (Novozyme 435). Glycerol obtained from transesterification reactions could be directly converted to GC. The reactions were optimized using the response surface methodology (RSM) separately. The optimal factors, which are enzyme loading, molar ratio of dimethyl carbonate to soybean oil, water content, and reaction temperature, were derived from the response optimizer. The results of optimization for biodiesel and GC production were re-analyzed by overlapping the contour plots of the factors. The following were the optima obtained: enzyme loading of 25 g/L, molar ratio of 15:1, water content of 0.082% (v/v), and reaction temperature of 59.65 °C. When the co-production of biodiesel and GC was conducted using the optima, biodiesel and GC production were achieved with conversions of 97.6% and 95.5%, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Solvent-free production of biodiesel and glycerol carbonate (GC) was developed. </LI> <LI> Statistical analysis enabled process optimization. </LI> <LI> Biodiesel and GC were achieved with 97.6% and 95.5% conversion, respectively. </LI> </UL> </P>
Clinical Manifestations and Surgical Treatment Outcomes of Paranasal Sinus Osteoma
Cho Ara,Jung Youngrak,Park Ju Ha,Jeong Yeonsu,Cho Hyung-Ju 대한비과학회 2022 Journal of rhinology Vol.29 No.1
Background and Objectives: Osteomas are the most common benign tumors of the nasal cavity and paranasal sinuses (PNSs). In this study, clinical features and imaging findings were analyzed in patients with osteoma confirmed by ostiomeatal unit (OMU) computed tomography (CT) and PNS CT, and the surgical treatment performed at our hospital was introduced.Methods: The Severance Clinical Research Analysis Portal (SCRAP) service of Severance Hospital was used to collect research data. A total of 128 cases of osteomas of the nasal cavity or PNSs confirmed by OMU CT or PNS CT was retrospectively reviewed, including the location and size of the osteoma, clinical features, accompanying findings on imaging tests, and cases of surgical treatment.Results: In this study, osteomas were found in about 0.55% of patients who underwent computed tomography. Osteomas were most frequently found in the ethmoid sinus, followed by the frontal sinus, fronto-ethmoid sinus, maxillary sinus, intranasal sphenoid sinus, and maxillary sinus-ethmoid sinus. Patients with osteomas complained of symptoms such as rhinorrhea, postnasal drip, nasal congestion, hyposmia, headache, visual disturbance, and lacrimal duct obstruction.Conclusion: Surgical treatment was considered for patients presenting with severe headache, visual field symptoms, or accompanying rhinosinusitis. Surgery was performed by endoscopic or external approaches depending on location and size of the osteoma.
Analysis of Electrical Characteristics of AlGaN/GaN on Si Large SBD by Changing Structure
Lee, Hyun-Soo,Jung, Dong Yun,Park, Youngrak,Jang, Hyun-Gyu,Lee, Hyung-Seok,Jun, Chi-Hoon,Park, Junbo,Mun, Jae Kyoung,Ryu, Sang-Ouk,Ko, Sang Choon,Nam, Eun Soo The Institute of Electronics and Information Engin 2017 Journal of semiconductor technology and science Vol.17 No.3
We investigated the improvement in electrical characteristics of large AlGaN/GaN on Si Schottky barrier diode (SBD) induced by structural change to achieve a better trade-off between the forward and reverse performance to obtain high power conversion efficiency in PFC converter. Using an optimized dry etch condition for a large device, we fabricated three-types of SBD with 63 mm channel width: conventional, recessed, recessed dual-anode-metal SBD. The recessed dual-anode-metal SBD exhibited a very low turn-on voltage of 0.34 V, a high forward current of 1.63 A at 1.5 V, a leakage current of $114{\mu}A$ at -15 V, a breakdown voltage of 794 V.