• Journal of Chest Surgery
• /
• v.28 no.10
• /
• pp.935-938
• /
• 1995

Two cases of severe caustic injury of the hypopharynx, esophagus, and stomach are presented. Restoration of digestive continuity was accomplished by retrosternal isoperistaltic interposition of the transverse and left colon on the post-injury 73rd and 66th day respectively. The upper oro-colon continuity was made by a cervical approach, a vertical incision at the posterior hypopharyngeal wall, and interrupted one-layer sutures using 3-0 Dacron suture materials. The distal continuity was made by colojejunostomy between the transposed colon and proximal jejunum. There was no event after the operation in both cases. The posterior vertical hypopharyngotomy and hypopharyngocolostomy at the early post-injury period may be the preferred procedure to obtain normal deglutition in patients with esophageal stricture associated with hypopharyngeal injury.

• Journal of The Korean Society of Clinical Toxicology
• /
• v.3 no.2
• /
• pp.99-102
• /
• 2005

The caustic drugs are classified into acid and alkali. Oral intake of these drugs cause histological injuries to the surfaces of oral cavity, laryngopharynx, and esophagus. Caustic drugs such as detergents and brilliants are easily contacted at homes. However, until now, the epidemiology and the clinical statistics of caustic drug ingestion in Korea were not carried out. This is a case report of sodium hydroxide - lye, a caustic drug more toxic than the others - ingestion with complication of gastroesophageal perforation, rapidly progressed mediastinitis and prompt death in the course of treatment.

• Journal of the Optical Society of Korea
• /
• v.8 no.1
• /
• pp.34-52
• /
• 2004

Over the past decade the experimental technique of THz time domain spectroscopy (㎔- TDS) has proved to be a versatile method for investigating a wide range of phenomena in the ㎔ or far infrared spectral region from 100 ㎓ to 5 ㎔. This paper reviews some recent results of the Ultrafast ㎔ Research Group at Oklahoma State University using ㎔-TDS as a characterization tool. The experimental technique is described along with recent results on ㎔ beam propagation and how ㎔ beam profiles arise from propagation of pulse fronts along caustics. To illustrate how spatio-temporal electric field measurements can determine material properties over a wide spectral range, propagation of ㎔ pulses through systems exhibiting frustrated total internal reflection (FTIR) are reviewed. Finally two potential metrology applications of ㎔-TDS are discussed, thin film characterization and non-destructive evaluation of ceramics. Although ㎔-TDS has been confined to the research laboratory, the focus on application may stimulate the adoption of ㎔- TDS for industrial or metrology applications.

• Journal of Information Processing Systems
• /
• v.17 no.4
• /
• pp.737-753
• /
• 2021

As the demand for high-quality rendering for mixed reality, videogame, and simulation has increased, global illumination has been actively researched. Monte Carlo path tracing can realize global illumination and produce photorealistic scenes that include critical effects such as color bleeding, caustics, multiple light, and shadows. If the sampling rate is insufficient, however, the rendered results have a large amount of noise. The most successful approach to eliminating or reducing Monte Carlo noise uses a feature-based filter. It exploits the scene characteristics such as a position within a world coordinate and a shading normal. In general, the techniques are based on the denoised pixel or sample and are computationally expensive. However, the main challenge for all of them is to find the appropriate weights for every feature while preserving the details of the scene. In this paper, we compare the recent algorithms for removing Monte Carlo noise in terms of their performance and quality. We also describe their advantages and disadvantages. As far as we know, this study is the first in the world to compare the artificial intelligence-based denoising methods for Monte Carlo rendering.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.109.2-109.2
• /
• 2012

Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this study, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions.

• Journal of Chest Surgery
• /
• v.28 no.11
• /
• pp.1032-1037
• /
• 1995

Between September 1988 and December 1993, 32 cases of benign esophageal stricture, of which 12 males and 20 females, were managed in Seoul National University Hospital hospital. Their age ranged from 2 to 61 years, and the mean age was 33.9 years. The ingestion of caustic agent was the most common cause, and the caustic material was acid in 16 patients [58% and alkali in 11patients [39% . Nearly all of the patients complained of dysphagia, and some of chest pain, epigastric pain, weight loss, vomiting, general malaise, and dyspnea. The most frequent site of stricture was found in the upper thoracic esophagus with 34% incidence followed by the lower thoracic esophagus[28% , whole esophagus[19% , and the mid esophagus[16% . The operations performed were 17[53% ECG[esophagocologastrostomy , 5[16% PCG[pharyngocologastrostomy , 5[16% EG[esophagogastrostomy , 2 EJG [esophagojejunogastrostormy by free jejunal graft , and 1 case each of EJ [esophagojejunostomy , esophageal end to end anastomosis, jejunostomy only, and gastrostomy only. In 23 patients [72% , diseased esophaguses were resected, using transhiatal total esophagectomy in 15 [47% and transthoracic partial esophagectomy in 8 [25% . Of those 23 patients, 3 patients [9.4% were diagnosed as esophageal carsinoma on microscopic examination. The postoperative most common complications were unilateral vocal cord palsy in 6 patients [19% , followed by cervical anastomosis leakage in 4 patients [12.5% , wound infection in 2 patients [6% , and pneumothorax in 2 patients [6% . Late death occurred 8 months after the operation in one patient, which was associated with infection due to anastomotic leakage. Our experience shows that the rate of mortality and the morbidity were low in patients receiving surgical management for esophageal stricture and that the cancer transformation rate was high. We recommend esophageal reconstruction surgery with esophagectomy [transhiatal or transthoracic for the esophageal stricture because it can avoid a chance of prevent cancer transformation.

• Journal of The Korean Society of Clinical Toxicology
• /
• v.13 no.2
• /
• pp.87-94
• /
• 2015

Purpose: We investigated comparison of clinical characteristics and prognosis by initial endoscopic severity in caustic injury and then discussed predisposing factors which can be helpful in predicting the prognosis and determining the treatment. Methods: This study was a retrospective review of medical records from patients over the age of 15, who underwent initial endoscopy for caustic injury from April 2007 through November 2014. Patients were classified according to two groups based on the initial endoscopic finding by Zargar's classification: patients with grade 0, I, IIa at esophagus (low risk group) and patients with grade IIb, IIIa, IIIb at esophagus (high risk group). The two groups were then compared. Results: A total of 55 patients were included (low risk group [n=44] vs. high risk group [n=11]). Old age (p<0.001), large amount of ingestion (p<0.05), oropharyngeal symptoms (p<0.01), high SOFA score (p<0.001), high WBC count (p<0.05), low base excess (p<0.01), and HCO3 (p<0.05) were statistically significant factors in the high risk group. A poor prognosis was observed for hospital stay (p<0.001), ICU admission (p<0.001), mortality (p<0.01), and stricture (p<0.001) in the high risk group. Conclusion: Clinical characteristics including age, amount of ingestion, oropharyngeal symptoms, SOFA score, WBC count, base excess, and $HCO_3$ can be helpful in the decision to undergo initial endoscopy and risk assessment by initial endoscopic severity can be helpful in predicting prognosis and determining the treatment plan.

• Journal of The Korean Astronomical Society
• /
• v.42 no.3
• /
• pp.39-45
• /
• 2009

We investigate the degeneracy in the pattern of central microlensing perturbations of a pair of planetary systems where the planets are located from the primary with projected separations in units of the Einstein radius s and $s^{-1}$, respectively. From this, we confirm the fact that although alike, the patterns of central perturbations induced by a close (s < 1) planet and a wide (s > 1) planet are not identical and the degree of difference depends on the planet/primary mass ratio and the planet-primary separation. We find that the difference can be greater than 5% for planetary systems with lensing parameters located in the parameter space of (1/1.8 < |s| < 1.8, q > $5{\times}10^{-3}$), (1/1.3 < |s| < 1.3, q > $1{\times}10^{-3}$), and (1/1.2 < |s| < 1.2, q > $5{\times}10^{-4}$), where q represents the planet/primary mass ratio. Although this range occupies a small fraction of the entire parameter space of planetary systems, we predict that the chance of resolving the close/wide degeneracy would not be meager considering that the planet detection efficiency is higher for planets with resonant separations (s $\sim$ 1) and heavier masses. We also find that the differences between the perturbation patterns are basically caused by the effect of the planetary caustic. This explains the tendency of the perturbation difference where (1) the difference increases as the planet/primary mass ratio increases and the separation approaches the Einstein radius, (2) the region of major difference is confined within the region around the line connecting the central and the planetary caustics, and (3) a wide (close) planetary system has a more extended central perturbation region toward the (opposite) direction of the planet.

• Journal of Environmental Science International
• /
• v.20 no.12
• /
• pp.1617-1624
• /
• 2011

Caustic (NaOH) solution is used to remove $H_2S$ from hydrocarbon streams in petroleum refining industry, gradually being, so called, spent sulfidic caustic (SSC) which has high levels of $H_2S$ and alkalinity. Thus, SSC can be used as an electron donor and a buffering agent for autotrophic denitrification. As SSC, however, contains some non-biodegradable organics, air stripping was conducted to remove the non-biodegradable organics. As a result, over 93 % of the non-biodegradable organics was removed within 30 min of aeration. Then, $Na_2S_2O_3{\cdot}5H_2O$, methanol and organic matters, which are produced from a biodiesel production plant, were added to reform the air-stripped SSC and their products being referred to new sulfidic caustics (NSCs) I, II and III, respectively. Thereafter, to investigate the effect of these products on the removal of COD and TN, these products were injected to a biological nitrogen removal (BNR) process, resulting in additional 44 % TN removal without noticeable increase in the effluent COD level. Therefore, it can be said that the BNR process is a promising option to treat NSC as demonstrated in this study whose results can be useful for developing resource recovery technologies.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.48.1-48.1
• /
• 2010

Four of nine exoplanets found by microlensing were detected by the resonant caustic, which represents the merging of the planetary and central caustics at the position when the projected separation of a host star and a bounded planet is s~1. One of the resonant caustic lensing events, OGLE-2005-BLG-169, was a caustic-crossing high-magnification event with A_max ~800 and the source star was much smaller than the caustic, nevertheless the perturbation was not obviously apparent on the light curve of the event. In this paper, we investigate the perturbation pattern of the resonant caustic to understand why the perturbations induced by the caustic do not leave strong traces on the light curves of high-magnification events despite a small source/caustic size ratio. From this study, we find that the regions with small magnification excess around the center of the resonant caustic are rather widely formed, and the event passing the small-excess region produces a high-magnification event with a weak perturbation that is small relative to the amplification caused by the star and thus does not noticeably appear on the light curve of the event. We also find that the positive excess of the inside edge of the resonant caustic and the negative excess inside the caustic become stronger and wider as q increases, and thus the resonant caustic-crossing high-magnification events with the weak perturbation occur in the range of q $\leq$ 10-4. We determine the probability of the occurrence of events with the small excess $|\varepsilon|{\leq}3%$ in high-magnification events induced by a resonant caustic. As a result, we find that for the Earth-mass planets with a separation of ~2.5 AU the resonant caustic high-magnification events with the weak perturbation can occur with a significant frequen.