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Abstract A tokamak relies on the axisymmetric magnetic fields to confine fusion plasmas and aims to deliver sustainable and clean energy. However, misalignments arise inevitably in the tokamak construction, leading to small asymmetries in the magnetic field known as error fields (EFs). The EFs have been a major concern in the tokamak approaches because small EFs, even less than 0.1%, can drive a plasma disruption. Meanwhile, the EFs in the tokamak can be favorably used for controlling plasma instabilities, such as edge-localized modes (ELMs). Here we show an optimization that tailors the EFs to maintain an edge 3D response for ELM control with a minimized core 3D response to avoid plasma disruption and unnecessary confinement degradation. We design and demonstrate such an edge-localized 3D response in the KSTAR facility, benefiting from its unique flexibility to change many degrees of freedom in the 3D coil space for the various fusion plasma regimes. This favorable control of the tokamak EF represents a notable advance for designing intrinsically 3D tokamaks to optimize stability and confinement for next-step fusion reactors.

In gas–metal arc welding (GMAW), the welding quality is influenced by various factors, including the welding conditions and external environment. Achieving a high welding quality requires careful observation and control. Welding monitoring is crucial for validating a planned welding process and assessing its quality. This study introduces a vision system for the online acquisition of clear molten pool images. It uses a small camera equipped with a complementary metal-oxide-semiconductor sensor during GMAW, as well as a method for constructing this system. The proposed vision system does not require triggering using devices such as field-programmable gate arrays, facilitating lower costs and online quality monitoring under various welding conditions during mild-steel GMAW. Accurate measurement of radiation from the weld is essential for clear observation of the molten pool during welding, emphasizing the importance of selecting an optical system with appropriate lenses and filters. In addition, appropriate digital camera parameters must be set for monitoring. High-quality images were successfully captured using the proposed method, and the image quality was evaluated using the blind/referenceless image spatial quality evaluator algorithm.

For manufacturing components with thick plates, such as in the heavy equipment and shipbuilding industries, the gas metal arc welding (GMAW) process is applied. Among the components that apply the thick plate GMAW process, there are groove butt joints, which are fabricated through multi-pass welding. Various welding qualities are managed in multi-pass welding, and the root-pass weld is controlled to ensure complete joint penetration (CJP). Currently, the state of complete joint penetration during root-pass welding is managed visually, making it difficult to confirm the penetration condition in real time. Therefore, there is a need to predict the penetration condition in real time. In this study, we propose a convolutional neural network (CNN)-based prediction model that can classify penetration conditions using welding current and voltage data from the root pass of V-groove butt joints. The root gap of the joints was varied between 1.0 and 2.0 mm, and the wire feed rate was adjusted. During welding, the current and voltage were measured. The welding current and voltage are transformed into a short-time Fourier transform (STFT) representation depicting the arc and wire extension lengths. The transformed dynamic resistance STFT information serves as the input variable for the CNN model. Preprocessing steps, including thresholding, are applied to optimize the input variables. The CNN architecture comprises three convolutional layers and two pooling layers. The model classifies penetration conditions as partial joint penetration (PJP), CJP, and burn-through, achieving a high accuracy of 97.8%. The proposed method facilitates the non-destructive evaluation of the root-pass welding quality without expensive monitoring equipment, such as vision cameras. It is expected to be immediately applied to the thick plate welding process using readily available welding data.

Resonant layers in a tokamak respond to non-axisymmetric magnetic perturbations by amplifying the mode amplitude and balancing the plasma rotation through magnetic reconnection and force balance, respectively. This resonant response can be characterized by local layer parameters and especially by a single quantity in the linear regime, the so-called inner-layer Δ. The computation of Δ under two-fluid drift-MHD formalism has been progressed by reducing the order of the system in the phase space, where the shielding current is approximated as being only carried by electrons, a posteriori . In this study, we relax the approximation and compute Δ accounted for by the parallel flow associated with the ion shielding current. The posteriori is numerically verified in great agreement with the original SLAYER developed in a previous paper (J.-K. Park 2022 Phys. Plasmas 29 072506). Extending the resonant layer response theory to high β plasmas, our research findings answer two important questions: how the parallel flow influences the resonant layer response and why the parallel flow effect appears in high β plasmas. The complicated plasma compression in high β regime allows the parallel flow response to give rise to the ion shielding current, which not only shifts the zero-crossing condition of the ExB flow but also enhances the field penetration threshold. Technically, the Riccati matrix transformation method is adapted to handle the numerical stiffness due to the increased order of the system. The high fidelity of this numerical method makes use of further extension of the model to higher-order systems to take other physical phenomena into account. This work is envisaged to predict the resonant layer response under high β fusion reactor conditions.

A variety of proton pump inhibitors (PPIs) have been developed in Korea since the introduction of omeprazole (the first PPI) in 1989. PPIs have served as the basic therapeutic approach for the management of gastric acid-related diseases for 30 years and remain among the most widely used drugs. Recently, potassium-competitive acid blockers (PCABs) have been developed both in Korea and abroad, demonstrating superior or non-inferior effects compared to existing PPIs in treating gastroesophageal reflux disease or Helicobacter pylori eradication, among others. Indications vary based on the various types and dosages of PPIs and PCABs, and several factors, including patients’ underlying disease, safety profile, particularly with regard to drug-drug interactions, and types of formulations of PPIs and PCABs need to be considered prior to prescribing these medications. In this article, we discuss the criteria for reimbursement of various PPIs and PCABs in Korea, along with considerations for prescribing these drugs based on patients’ underlying diseases.

Background/Aims The eradication success rate of Helicobacter pylori (H. pylori) infection with a first-line standard triple therapy (STT) has been decreasing in Korea. However, treatment outcomes of H. pylori infection in Yeongdong, Gangwon Province have been scarcely reported. This study aimed to investigate the treatment outcomes of H. pylori infection in a single tertiary care hospital with regional characteristics. Materials and Methods From July 2018 to June 2019, a total of 592 patients who underwent STT consisting of a proton pump inhibitor, amoxicillin, and clarithromycin for 7 to 14 days as a first-line H. pylori eradication therapy were included. Demographic data and treatment outcomes were retrospectively reviewed using medical records. Results The median age of 592 patients was 58 years (range 23 to 86) and 329 patients (55.6%) were men. The indication for eradication therapy included chronic atrophic gastritis (57.9%), peptic ulcer disease (19.6%), and gastric neoplasm after endoscopic resection (5.9%). Most patients (92.2%) received a 7-day course of STT. Eradication rate of STT was 64.0% (379/592). Rescue therapy was performed in 146 patients, and the final eradication rate reached 85.6% (507/592). Conclusions Eradication rate of STT in Yeongdong area of Gangwon Province was unsatisfactory, warranting the consideration of a first-line eradication regimen other than STT.

Abstract The optimal timing of endoscopy in patients with acute upper gastrointestinal bleeding (UGIB) remains controversial. In this study, we investigated the clinical outcomes of urgent endoscopy in patients with UGIB compared with elective endoscopy. From January 2016 to December 2018, consecutive patients who visited the emergency department and underwent endoscopy for clinical manifestations of acute UGIB, including variceal bleeding, were eligible. Urgent endoscopy (within 6 h) and elective endoscopy (after 6 h) were defined as the time taken to perform endoscopy after presentation to the emergency department. The primary outcome was mortality rate within 30 days. A total of 572 patients were included in the analysis. Urgent endoscopy was performed in 490 patients (85.7%). The 30-day mortality rate did not differ between the urgent and elective endoscopy groups (5.3% and 6.1%, p = 0.791). There was no difference regarding the recurrent bleeding rate, total amount of transfusion, or length of hospital between the groups. In multivariate analysis, age and the amount of transfusion were associated with mortality. Urgent endoscopy was not associated with a lower 30-day mortality rate compared with elective endoscopy in patients with acute UGIB.

Abstract Background Ingested foreign objects frequently require emergency removal. This study aimed to investigate the clinical outcomes of endoscopic removal of foreign bodies from the upper gastrointestinal tract and the risk factors for adverse events. Methods Adults (> 18 years) who underwent endoscopic management of ingested foreign bodies at two centers, one inland and one on the coast, between January 2008 and December 2017 were eligible. Clinical characteristics and procedure-related outcomes were retrospectively reviewed. Patients were divided into two groups, based on whether the foreign bodies were sharp or blunt in shape. Results A total of 853 patients aged 19–96 years were analyzed. Ingestion of fish bones was more common in the coastal area, whereas ingestion of food boluses was more common in the inland area. The duration of impaction ranged from 1 h to over 1 month and was significantly longer in patients who ingested blunt than sharp foreign bodies (15 vs. 5 h, p

Abstract Background Risk stratification before endoscopy is crucial for proper management of patients suspected as having upper gastrointestinal bleeding (UGIB). There is no consensus regarding the role of nasogastric lavage for risk stratification. In this study, we investigated the usefulness of nasogastric lavage to identify patients with UGIB requiring endoscopic examination. Methods From January 2017 to December 2018, patients who visited the emergency department with a clinical suspicion of UGIB and who underwent nasogastric lavage before endoscopy were eligible. Patients with esophagogastric variceal bleeding were excluded. The added predictive ability of nasogastric lavage to the Glasgow–Blatchford score (GBS) was estimated using category-free net reclassification improvement and integrated discrimination improvement. Results Data for 487 patients with nonvariceal UGIB were analyzed. The nasogastric aspirate was bloody in 67 patients (13.8 %), coffee-ground in 227 patients (46.6 %), and clear in 193 patients (39.6 %). The gross appearance of the nasogastric aspirate was associated with the presence of UGIB. Model comparisons showed that addition of nasogastric lavage findings to the GBS improved the performance of the model to predict the presence of UGIB. Subgroup analysis showed that nasogastric lavage improved the performance of the prediction model in patients with the GBS ≤ 11, whereas no additive value was found when the GBS was greater than 11. Conclusions Nasogastric lavage is useful for predicting the presence of UGIB in a subgroup of patients, while its clinical utility is limited in high-risk patients with a GBS of 12 or more.

Helicobacter pylori (H. pylori) is the most prevalent bacterial pathogen that infects approximately half of the world’s population. It is well known that H. pylori causes chronic gastritis, peptic ulcer, and gastric cancer. H. pylori can also be associated with other gastrointestinal diseases. Epidemiologic studies have reported an inverse correlation between H. pylori infection and gastroesophageal reflux disease. However, the results of H. pylori eradication in patients with gastroesophageal reflux disease were not consistent with epidemiologic studies. Many studies have reported symptomatic improvement in uninvestigated dyspepsia and functional dyspepsia (FD) following H. pylori eradication, suggesting that H. pylori is the cause of dyspepsia. Therefore, it has been suggested that H. pylori-associated dyspepsia should be considered an entity distinct from FD and only the patients with persistent symptoms following eradication should be considered as having FD. A majority of studies also support an association of H. pylori with colon neoplasms and an inverse correlation with inflammatory bowel disease. However, no association of H. pylori with irritable bowel syndrome has been reported.

Abstracts Background Lymph node (LN) metastasis is negligible in early gastric cancer (EGC) within expanded criteria for endoscopic submucosal dissection (ESD). However, regional lymph nodes in abdominal CT scans are sometimes enlarged in patients with EGC within the expanded criteria for endoscopic submucosal dissection (ESD). In this study, we investigated the clinical significance of regional lymph node enlargement on abdominal CT scan in patients with EGC within the expanded criteria for ESD. Methods From December 2010 to April 2015, among 301 patients with EGC within the ESD expanded criteria, 47 patients with regional lymph node enlargement shown by abdominal CT scan were prospectively enrolled. We performed surgical resection or periodic follow-up with abdominal CT scans and upper endoscopy every 6 months to evaluate whether the enlarged lymph nodes are due to metastasis or a reactive change. Results The mean age of the 47 patients (38 males, 9 female) was 64.8 years. The enlarged lymph nodes were usually single (26/47, 44.6%) and sized as follows: 11 nodes were ≤ 5 mm, 19 were 6–10 mm, and 17 were ≥ 10 mm. Four of the 47 patients initially underwent surgical resection, and 8 patients underwent surgical resection after ESD. However, there was no lymph node metastasis in surgical specimens. Thirty-five patients received ESD and periodically followed up at a median duration of 56 months (IQR: 44–59 month). The enlarged lymph node disappeared in 12 of 35 patients, decreased in 9 patients and remained the same size in 13 patients, and increased in 1 patient. Conclusion Regional lymph node enlargement on abdominal CT scan in patients within expanded criteria for ESD of ECG may be not due to metastasis but a reactive change.

Phospholipase A2 group VI (PLA2G6)-associated neurodegeneration (PLAN) is an autosomal recessive neurodegenerative disease with a wide clinical spectrum; however, the genotype-phenotype correlation is unknown. Here, we report different phenotypes in one family with the same genotype. A 28-year-old male presented with slowly progressive gait disturbance with spasticity. Onset occurred at 11 years. Interestingly, his younger brother, a 24-year-old male, presented with progressive Parkinsonism, which began at 22 years. He showed excellent response to levodopa but developed a fluctuating medication response and levodopa-induced dyskinesia 1 year after starting levodopa medication. He also demonstrated hyperreflexia, but no spasticity. Dopamine transporter imaging showed reduced uptake in the bilateral putamen. In whole-exome sequencing and Sanger sequencing, a homozygous pathogenic variant (p. R747W) in the PLA2G6 gene was detected in both cases. Despite different clinical features, both subjects had hyperreflexia during the examination and claval hypertrophy was shown on the brain magnetic resonance imaging.

Although gastric hyperplastic polyps are recognized as benign lesions, there is concern regarding carcinomatous changes in the polyps, depending on their size. If the polyp size is larger than 1.0∼2.0 cm, endoscopic resection is usually recommended. Gastric hyperplastic polyps easily undergo changes in their shape and size over time. However, spontaneous regression of hyperplastic polyps is very rare. We present a recent case wherein gastric hyperplastic polyps disappeared spontaneously. We present the case along with a literature review.

The first-line therapy for Helicobacter pylori infection comprises triple therapy with the combination of a proton pump inhibitor (PPI), amoxicillin, and clarithromycin. However, the H. pylori eradication rate after PPI-based triple therapy has fallen below 80% in many countries, and even reached 70% in recent Korean studies. The main cause of eradication failure has been attributed to the increased antibiotic resistance of H. pylori. To overcome the limitations of the current eradication therapy, the maintenance of a high gastric pH, which increases the function of the antibiotics, may be a successful strategy. Potassium-competitive acid blockers (PCABs) inhibit H⁺, K⁺-ATPase in a reversible and K⁺-competitive manner and result in an almost complete inhibition of gastric acid secretion. However, the clinical development of most PCABs has been discontinued owing to their hepatic toxicity or similar efficacy to PPIs. Vonoprazan has a completely different chemical structure and higher pKa value compared with those of other PCABs and produces more potent and sustained acid inhibition. A recent phase III randomized study reported that vonoprazan was highly effective as a component of first-line or second-line triple therapy. In this study, we reviewed the literature regarding the role of PCAB in the eradication of H. pylori.

Background/Aims: Laryngopharyngeal reflux (LPR) is an extraesophageal manifestation of gastroesophageal reflux disease. Endoscopic assessment of LPR is needed for convenient diagnosis and documentation of treatment efficacy. The aim of this study was to investigate the interrater reliability of LPR among endoscopists based on endoscopic laryngeal images. Materials and Methods: Nineteen endoscopists participated in this study. Before the test, they completed an intensive education program by an otorhinolaryngologist on the reflux finding score (RFS), which is a validated laryngoscopic assessment of LPR. A total of 100 endoscopic laryngeal images were used for 3 tests of RFS. Cohen’s and Fleiss’ kappa coefficients were used to determine the degree of interrater agreement in the diagnosis of LPR. Results: In the first test, the mean of Cohen’s kappa coefficients for LPR diagnosis between the otorhinolaryngologist and each of the 19 endoscopists was 0.3. In the second test, after additional education, the mean kappa value was 0.32. Fleiss’ kappa coefficients for diagnosis of LPR among the 19 endoscopists in the first and second tests were 0.30 and 0.26, respectively. Conclusions: A short-term education program for endoscopists did not result in an improvement of accuracy in the diagnosis of LPR. Further studies using advanced educational programs for endoscopists are required.

Objective: To compare Helicobacter pylori ( H. pylori ) eradication rate of type 2 diabetic patients with non-diabetic subjects. Methods: In this multicenter prospective observational study, H. pylori -infected subjects were enrolled from three university-affiliated hospitals. Eradication regimen was triple therapy with standard dose of proton pump inhibitors (b.i.d), amoxicillin (1.0 g b.i.d), and clarithromycin (500 mg b.i.d) for 7 days. Urea breath test was performed 4 weeks after treatment. Various clinical and laboratory data were collected for identification of factors associated with successful eradication. Results: Totally, 144 subjects were enrolled and 119 (85 non-diabetic and 34 diabetic patients) were finally analyzed. Eradication rate was 75.6% and there was no difference between diabetic patients and non-diabetic subjects (73.5% vs 76.5%, p value: 0.814). Adverse drug reactions were reported in 44.5% of patients. In multivariate analysis for predicting H. pylori eradication in diabetic patients, HbA1c (⩾7.5%) was a significant factor affecting eradication rate (adjusted odds ratio: 0.100, 95% confidence interval: 0.011–0.909, p value: 0.041). Conclusion: Diabetes itself is not a major factor affecting H. pylori eradication. However, poor glucose control may harmfully affect H. pylori eradication.

Background/Aims The diagnostic efficacy of current tissue sampling techniques for gastric subepithelial tumors (SETs) is limited. Better tissue sampling techniques are needed to improve pathological diagnosis. The aim of this study was to evaluate the safety and efficacy of a new technique, mucosal incision and forceps biopsy, for reliable tissue sampling of gastric SETs. Methods This study enrolled 12 consecutive patients who underwent mucosal incision and forceps biopsy of gastric SETs between November 2011 and September 2014 at Gangneung Asan Hospital. The medical records of patients were reviewed retrospectively. The safety and diagnostic yield of this method were evaluated. Results By performing mucosal incision and forceps biopsy, we were able to provide a definitive histological diagnosis for 11 out of 12 cases. The pathological diagnoses were leiomyoma (3/11), gastrointestinal stromal tumor (GIST; 2/11), lipoma (2/11), schwannoma (1/11), and ectopic pancreas (3/11). In cases of leiomyoma (n=3) and GIST (n=2), tissue samples were of sufficient size to allow immunohistochemical staining. In addition, the mitotic index was evaluated in two cases of GIST. There were no procedure-related complications. Conclusions Mucosal incision and forceps biopsy can be used as one of several methods to obtain adequate tissue samples from gastric SETs.

Background/Aims Prokinetic agents and neuromodulators are among the treatment options for functional dyspepsia (FD), but their comparative efficacy is unclear. We aimed to compare the efficacy of mosapride controlled-release (CR) and nortriptyline in patients with FD after 4 weeks of treatment. Methods Participants with FD were randomly assigned (1:1) to receive mosapride CR (mosapride CR 15 mg and nortriptyline placebo) or nortriptyline (mosapride CR placebo and nortriptyline 10 mg) in double-placebo, double-blinded, randomized controlled, parallel clinical study. The primary endpoint was defined as the proportion of patients with overall dyspepsia improvement after 4 weeks treatment. The secondary endpoints were changes in individual symptom scores, anxiety, depression, and quality of life. Results One hundred nine participants were recruited and assessed for eligibility, and 54 in the mosapride CR group and 50 in the nortriptyline group were included in the modified intention-to-treat protocol. The rate of overall dyspepsia improvement was similar between groups (53.7% vs 54.0%, P = 0.976). There was no difference in the efficacy of mosapride CR and nortriptyline in a subgroup analysis by FD subtype (59.3% vs 52.5% in postprandial distress syndrome, P = 0.615; 44.4% vs 40.0% in epigastric pain syndrome, P = > 0.999; 50.0% vs 59.1% in overlap, P = 0.565; respectively). Both treatments significantly improved anxiety, depression, and quality of life from baseline. Conclusion Mosapride CR and nortriptyline showed similar efficacy in patients with FD regardless of the subtype. Both treatments could be equally helpful for improving quality of life and psychological well-being while also relieving dyspepsia. [ABSTRACT FROM AUTHOR]

Functional dyspepsia (FD) has a diverse pathophysiology and treatment is difficult. Translational research to understand its pathophysiology is underway. Hormonal factors, including ghrelin, seem promising, offering an understanding of appetite and eating. Functional MRI brain study can expand our knowledge of the brain-gut axis. Finally, immune systems research, including mast cells, can help with comprehensive understanding of FD. The clinical approaches based on these translational research projects are necessary to improve understanding of FD, leading to more effective treatment. (Korean J Gastroenterol 2016;68:132-137)

Background/Aims There is growing interest in whether Helicobacter pylori eradication (HPE) can affect body weight. Methods Data from 5 universities between January 2013 and December 2019 were analyzed retrospectively. H. pylori -positive subjects who had body weight measurements taken at least twice at intervals of 3 months or longer were included. Using propensity score (PS)-matched data, changes in body mass index (BMI) and the lipid profile after HPE were compared with the non-HPE group. Results Among 363 eligible patients, 131 HPE patients were PS-matched to 131 non-HPE patients. The median intervals between the measurements were 610 (range, 154-1250) days and 606 (range, 154-1648) days in the HPE and non-HPE groups, respectively. In both groups, the mean BMI increased (from 24.5 kg/m² to 24.7 kg/m² in the HPE group, and from 24.4 kg/m² to 24.5 kg/m² in the non-HPE group). The 2 groups did not show significantly different changes (P = 0.921). In the lowest baseline BMI quartile, the BMI increased after HPE by 1.23 (standard deviation [SD], 3.72) kg/m² (P = 0.060), and the non-HPE group showed a decreased BMI at the time of follow-up (by -0.24 [SD, 5.25] kg/m²; P = 0.937) (between-group P = 0.214). Triglyceride levels increased after HPE (mean: 135 [SD, 78] to 153 [SD, 100] mg/dL; between-group P = 0.053). Conclusion The overall BMI change was not significantly different between the HPE and non-HPE groups, but patients with low BMI showed a tendency to gain weight after HPE. Triglyceride levels increased after HPE with marginal significance. [ABSTRACT FROM AUTHOR]