Hazardous area classification design is required to reduce the explosion risk in process plants. Among the international design guidelines, only IEC 60079-10-1 proposes a new type of zone, namely zone 2 NE, to prevent explosion hazards. We studied how to meet the zone 2 NE grade for a facility handling hydrogen gas, which is considered as most dangerous among explosive gases. Zone 2 NE can be achieved considering the grade of release, as well as the availability and effectiveness of ventilation, which are factors indicative of the facility condition and its surroundings. In the present study, we demonstrate that zone 2 NE can be achieved when the degree of ventilation is high by accessing temperature, pressure, and size of leak hole. The release characteristic can be derived by substituting the process condition of the hydrogen gas facility. The equations are summarized considering relation of the operating temperature, operating pressure, and size of leak hole. Through this relationship, the non-hazardous condition can be realized from the perspective of inherent safety by the combination of each parameter before the initial design of the hydrogen gas facility.

Hazardous area classification design is required to reduce the explosion risk in process plants. Among the international design guidelines, only IEC 60079-10-1 proposes a new type of zone, namely zone 2 NE, to prevent explosion hazards. We studied how to meet the zone 2 NE grade for a facility handling hydrogen gas, which is considered as most dangerous among explosive gases. Zone 2 NE can be achieved considering the grade of release, as well as the availability and effectiveness of ventilation, which are factors indicative of the facility condition and its surroundings. In the present study, we demonstrate that zone 2 NE can be achieved when the degree of ventilation is high by accessing temperature, pressure, and size of leak hole. The release characteristic can be derived by substituting the process condition of the hydrogen gas facility. The equations are summarized considering relation of the operating temperature, operating pressure, and size of leak hole. Through this relationship, the non-hazardous condition can be realized from the perspective of inherent safety by the combination of each parameter before the initial design of the hydrogen gas facility.

PURPOSE: To evaluate the mean width of anterior commissure of true vocal cord in Korean adults by measuringits dimension on spiral CT scans. MATERIALS AND METHODS: We reviewed the CT scans of 53 Korean adults(age range,23-73years; mean age 39.2years; M:F=41:12) without laryngeal disorders. Spiral CT scanning was performed aroundthe anterior commissure with 1mm slice thickness and table incrementation for 15 seconds. The anteroposteriorwidth of the anterior commissure was measured on CT scan where the true vocal cord and arytenoid, cricoid andthyroid cartilages were all present. We determined the mean width of the anterior commissure and whether there wasa relationship between age and the width of the anterior commissure. RESULTS: The width of the anteriorcommissure was between 0.9mm and 2.3mm ; mean width was 1.60+/-0.38mm(mean+/-SD). Using two SDs above the mean wouldhave defined 2.36mm as the upper limit of normal width. Statistically, no significant correlation existed betweenthe age and the width of the anterior commissure(p>0.05). CONCLUSION: An awareuess of the normal width range ofthe anterior commissure in Korean adults evaluated by spiral CT enhances the possibility of early detection ofinvasion of the anterior commissure by glottic cancer.
Adult* ; Cartilage ; Humans ; Tomography, Spiral Computed* ; Tomography, X-Ray Computed ; Vocal Cords*

The incidence of thymolipoma or thynuc cyst is very rare among the tumors of thymic origin, which are usually benign or invasive thymoma. Thymic tumor has been found among 10 to 15% of the patients with myasthenia gravis(MG). However the patients with thymolipoma or thynuc cyst rarely manifestated as MG. Moreover the case of MG with thymolipoma and thymic cyst is extremely rare ; Only one case has been reported hitherto. We hereby report a 41-year-old woman presenting as ocular MG with thymolipoma and thymic cyst. She complained diplopia, ptosis and headache, which had begun 3 months prior to admission and have been fluctuating thereafter. Ocular MG was confirmed by positive Tensilon and Jolly test. Her chest CT showed an enlarged thymus which turned out to be thymolipoma with thymic cyst on the pathologic examination. Although rare, thymolipoma and/or thymic cyst should be considered in the differential diagnosis of thymic tumor in MG.
Adult ; Diagnosis, Differential ; Diplopia ; Edrophonium ; Female ; Headache ; Humans ; Incidence ; Mediastinal Cyst* ; Myasthenia Gravis* ; Thymoma ; Thymus Gland ; Thymus Neoplasms ; Tomography, X-Ray Computed

OBJECTIVE: The authors undertook a study to compare three intraoperative guidance systems, which are intraoperative ultrasonography, stereotaxy and computer-assisted image-guided surgery (neuronavigation) in terms of time consuming during the preparation of these procedures. In this operative case-based study, we have investigated the ability and benefits of intraoperative grey-scale sonographic examination in the localizing of intracranial hemorrhage (ICH) in the brain. METHODS: We used B-mode ultrasonography (5-MHz, 1.2x2.5 mm sized probe) during 23 procedures (craniotomy or craniectomy ; 17, hematoma aspiration : 6) performed in the acute stage after head injury, hypertensive ICH, ruptured cerebral aneurysm. Seventeen patients who suffered from spontaneous ICH underwent stereotactic hematoma aspiration and fourteen patients underwent hematoma removal using neuronavigation system (spontaneous ICH ; 11, Arteriovenous malformation and aneurysm ; 3). We compared intraoperative ultrasonography-assisted hematoma removal with procedures with stererotaxy or neuronavigation system in respect of detection of the pathology and time consuming for preparation. RESULTS: Mean preparation time for stereotactic hematoma aspiration was 71.2 minutes (50-90 minutes), and mean preparation time for neuronavigation-guided surgery was 52.5 minutes (30-70 minutes). However, only 7.4 minutes (4-20 minutes) were needed for the preparation time of intraoperative ultrasonography. Moreover, intraoperative ultrasonography-guided surgery had many advantages compared to other image-guide surgery, such as capability of real-time monitoring and independency of brain shifting. However, there were several limitations too, which were relatively low resolution, artifact by air bubble during the procedure, and the lower echogenecity of liquified hematomas when a delay of several days was needed. Nevertheless, ultrasound-guided hematoma surgery could serve as minimally invasive treatment whenever hematoma evacuation seems to be advisable, at least as a first attempt. CONCLUSION: Based on this preliminary result, we concluded that intraoperative ultrasonographic examination during the surgical treatment of ICH was a non-invasive, useful, and simple diagnostic tool in the detection of the components and accompanying parts of the lesion. It was more useful than stereotaxy or neuronavigation system in the situation of emergent case such as an impending brain herniation.
Aneurysm ; Arteriovenous Malformations ; Artifacts ; Brain ; Cerebral Hemorrhage* ; Craniocerebral Trauma ; Hematoma ; Humans ; Intracranial Aneurysm ; Intracranial Hemorrhages ; Neuronavigation ; Pathology ; Surgery, Computer-Assisted* ; Ultrasonography*

BACKGROUND/AIMS: Although postpolypectomy fever (PPF) without colon perforation or hemorrhage is rare, its incidence and risk factors have not been investigated. The objective of this study was to analyze the incidence and risk factors for PPF among inpatients. METHODS: Seven patients with PPF were matched with 70 patients without PPF from a total of 3,444 patients who underwent colonoscopic polypectomy. The PPF incidence during index hospitalization after colonoscopy was calculated, and univariate and multivariate analyses were performed to calculate the adjusted odds ratios (ORs) for risk factors. RESULTS: PPF without bleeding or perforation in the colon occurred in seven patients (0.2%). The median age was 58 years for cases and 61 years for controls. The median interval from polypectomy to occurrence of fever was 7 hours, and the median duration of fever was 9 hours. Polyp size >2 cm (adjusted OR, 1.08; 95% confidence interval [CI], 1.01 to 1.15; p=0.02) and hypertension (adjusted OR, 14.40; 95% CI, 1.23 to 180.87; p=0.03) were associated with a significantly increased risk of PPF. PPF increased the length of hospitalization. CONCLUSIONS: Although the crude incidence of PPF is low, PPF may prolong hospitalization. Risk factors for PPF include hypertension and large polyps.
Case-Control Studies* ; Colon ; Colonoscopy ; Fever* ; Hemorrhage ; Hospitalization ; Humans ; Hypertension ; Incidence ; Inpatients ; Multivariate Analysis ; Odds Ratio ; Polyps ; Risk Factors

Patients with altered anatomy such as a Roux-en-Y anastomosis often present with various pancreaticobiliary problems requiring therapeutic intervention. However, a conventional endoscopic approach to the papilla is very difficult owing to the long afferent limb and acute angle of a Roux-en-Y anastomosis. Balloon-assisted enteroscopy can be used for endoscopic retrograde cholangiopancreatography (ERCP) in patients with altered anatomy. We experienced six cases of Roux-en-Y anastomosis with biliary problems, and attempted ERCP using single balloon enteroscopy (SBE). SBE insertion followed by replacement with a conventional endoscope was attempted in five of six patients. The papilla was successfully approached using SBE in all cases. However, therapeutic intervention was completed in only three cases because of poor maneuverability caused by postoperative adhesion. We conclude that in patients with Roux-en-Y anastomosis, the ampulla can be readily accessed with SBE, but longer dedicated accessories are necessary to improve this therapeutic intervention.
Anastomosis, Roux-en-Y* ; Cholangiopancreatography, Endoscopic Retrograde* ; Endoscopes ; Extremities ; Gastrectomy* ; Humans

BACKGROUND/AIMS: Cyclooxygenase-2 (COX-2), 15-hydroxyprostaglandin dehydrogenase (15-PGDH), and microsomal prostaglandin E synthase-1 (mPGEs-1) regulate prostaglandin E₂ (PGE₂) expression and are involved in colon carcinogenesis. We investigated the expression of PGE₂ and its regulating genes in sporadic human colon tumors and matched normal tissues. METHODS: Twenty colonic adenomas and 27 colonic adenocarcinomas were evaluated. COX-2 and 15-PGDH expression was quantified by real-time polymerase chain reaction. The expression of PGE₂ and mPGEs-1 was measured using enzyme-linked immunosorbent assay and Western blotting, respectively. RESULTS: The expression of COX-2, mPGEs-1, and PGE₂ did not differ between the adenomas and matched distant normal tissues. 15-PGDH expression was lower in adenomas than in the matched normal colonic tissues (P<0.001). In adenocarcinomas, mPGEs-1 and PGE₂ expression was significantly higher (P<0.001 and P=0.020, respectively), and COX-2 expression did not differ from that in normal tissues (P=0.207). 15-PGDH expression was significantly lower in the normal colonic mucosa from adenocarcinoma patients than in the normal mucosa from adenoma patients (P=0.018). CONCLUSIONS: Early inactivation of 15-PGDH, followed by activation of COX-2 and mPGEs-1, contributes to PGE₂ production, leading to colon carcinogenesis. 15-PGDH might be a novel candidate marker for early detection of field defects in colon carcinogenesis.
Adenocarcinoma ; Adenoma ; Blotting, Western ; Carcinogenesis* ; Colon* ; Cyclooxygenase 2 ; Enzyme-Linked Immunosorbent Assay ; Humans* ; Mucous Membrane ; Oxidoreductases* ; Real-Time Polymerase Chain Reaction

BACKGROUND/AIMS: Endoscopic mucosal resection with circumferential mucosal incision (CMI-EMR) may offer benefits comparable to those of endoscopic submucosal dissection (ESD), while requiring less technical proficiency than ESD. METHODS: We retrospectively compared the outcomes of CMI-EMR (n=34) and size-matched ESD (n=102), which were performed by a Korean endoscopist for colorectal epithelial lesions of 20–35 mm. Procedural parameters of CMI-EMRs performed by an American ESD novice (n=30) were compared with those performed by the Korean endoscopist. RESULTS: The lesion size was 22.3±3.9 mm and 22.9±2.4 mm in the CMI-EMR and size-matched ESD groups, respectively (p=0.730). The resection time was 12.7±7.0 minutes in the CMI-EMR group and 45.6±30.1 minutes in the ESD group (p<0.001). The en bloc resection rate was 94.1% in the CMI-EMR group and 100% in the ESD group (p=0.061). There were no differences in the en bloc resection and complication rates of CMI-EMRs between a Korean and an American endoscopist. CONCLUSIONS: For the treatment of moderate-size colorectal lesions, CMI-EMR showed a trend toward lower en bloc resection rate, but required shorter procedure time than ESD. CMI-EMR outcomes were similar when performed by a Korean ESD expert and an American ESD novice.
Colon ; Colorectal Neoplasms* ; Rectum ; Retrospective Studies

Gastric schwannomas are rare benign tumors among the mesenchymal tumor of the gastrointestinal tract, arising from the nerve tissue which has a schwann cell sheath. These neoplasms are grossly similar to gastrointestinal stromal tumor (GIST), however, the clinical course of GIST is more aggressive compared to that of schwannomas. Synchronous occurrence of gastric epithelial and subepithelial tumors is rare. Besides, most subepithelial lesions are GIST. We present the case of a 57-year-old male with synchronous gastric schwannoma and gastric adenoma in the stomach. We found a gastric subepithelial lesion incidentally, the size of which was increasing and tubular adenoma was discovered in the covering mucosa during endoscopy follow-up. The synchronous lesion was removed by wedge resection, which was diagnosed as schwannoma with adenoma.
Adenoma ; Endoscopy ; Follow-Up Studies ; Gastrointestinal Stromal Tumors ; Gastrointestinal Tract ; Humans ; Male ; Middle Aged ; Mucous Membrane ; Nerve Tissue ; Neurilemmoma ; Stomach