• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.6
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• pp.569-575
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• 1984

The characteristics of the stress corrosion cracking of SUS 304 stainless steel weldments were studied with the speciments of the constant displacement type under the environment of 42% MgC $l_{2}$ boiled solution (143.+.-.2.deg.C). The susceptibility of initiation and propagation of the stress corrosion crack was quantitatively inspected in the weld metal, heat affected zone and heat affected zone with including the reinforcement shape, respectively. Also, those susceptibility were discussed in connection with the change of mechanical and microstructural characteristics caused by heating cycle of welding. Main results obtained are as follows: (1)Stress corrosion cracking is easiest to initiate and propagate in the heat affected zone of weldment. (2)The susceptibility of stress corrosion cracking of the weldment is largely improved by eliminating the reinforcement part of the weld bead. (3)The dominant factor of the cracking susceptibility of the heat affected zone appeared to be the phenomenon of softening and sensitizing caused by welding heat cycle. (4)Under the low loading conditions, the behavior of stress corrosion cracking of the SUS 304 steel weldment is largely influenced by the pitting phenomenon in the front region of the main crack.

• Earthquakes and Structures
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• v.18 no.1
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• pp.73-82
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• 2020

With the coal mining depth increasing, both stress and gas pressure rapidly enhance, causing coal and gas outburst risk to become more complex and severe. The conventional method for prediction of coal and gas outburst adopts one prediction index and corresponding critical value to forecast and cannot reflect all the factors impacting coal and gas outburst, thus it is characteristic of false and missing forecasts and poor accuracy. For the reason, based on analyses of both the prediction indicators and the factors impacting coal and gas outburst at the test site, this work carefully selected 6 prediction indicators such as the index of gas desorption from drill cuttings Δh₂, the amount of drill cuttings S, gas content W, the gas initial diffusion velocity index ΔP, the intensity of electromagnetic radiation E and its number of pulse N, constructed the Bayes discriminant analysis (BDA) index system, studied the BDA-based multi-index comprehensive model for forecast of coal and gas outburst risk, and used the established discriminant model to conduct coal and gas outburst prediction. Results showed that the BDA - based multi-index comprehensive model for prediction of coal and gas outburst has an 100% of prediction accuracy, without wrong and omitted predictions, can also accurately forecast the outburst risk even for the low indicators outburst. The prediction method set up by this study has a broad application prospect in the prediction of coal and gas outburst risk.

• KSBB Journal
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• v.19 no.3
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• pp.192-199
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• 2004

In this work the production of glutathione (GSH) by yeast Saccharomyces cerevisiae and the monitoring of the process were studied. In shaking culture the production of GSH was high at initial pH value of 4 and at temperature of 30$^{\circ}C$. But when L-cysteine was added to the culture medium at the beginning of the cultivation, the productivity of GSH was low. In case 0,5% (v/v) of L-cysteine, glycine and glutamic acid were introduced to the culture medium in the exponential cell growth phase, high concentration of GSH (about 90 mg/L) was produced in the bioreactor. A fed-batch operation with stepwise glucose feeding strategy allowed to produce 102 mg/L of GSH. The cultivation processes were on-line monitored by a 2-dimensional fluorescence sensor. A few off-line data such as cell growth, cystein concentration, phosphate concentration and GSH productivity could be well correlated to the fluorescence intensity of some combinations of excitation and emission wavelengths.

• Radiation Oncology Journal
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• v.37 no.3
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• pp.193-200
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• 2019

Purpose: To explore the role of salvage radiotherapy (RT) for recurrent thymoma as an alternative to surgery. Materials and Methods: Between 2007 and 2015, 47 patients who received salvage RT for recurrent thymoma at Yonsei Cancer Center were included in this study. Recurrent sites included initial tumor bed (n = 4), pleura (n = 19), lung parenchyma (n = 10), distant (n = 9), and multiple regions (n = 5). Three-dimensional conformal and intensity-modulated RT were used in 29 and 18 patients, respectively. Median prescribed dose to gross tumor was 52 Gy (range, 30 to 70 Gy), with equivalent doses in 2-Gy fractions (EQD₂). We investigated overall survival (OS), progression-free survival (PFS), and patterns of failure. Local failure after salvage RT was defined as recurrence at the target volume receiving >50% of the prescription dose. Results: Median follow-up time was 83 months (range, 8 to 299 months). Five-year OS and PFS were 70% and 22%, respectively. The overall response rate was 97.9%; complete response, 34%; partial response, 44.7%; and stable disease, 19.1%. In multivariate analysis, histologic type and salvage RT dose (≥52 Gy, EQD₂) were significantly associated with OS. The high dose group (≥52 Gy, EQD₂) had significantly better outcomes than the low dose group (5-year OS: 80% vs. 59%, p = 0.046; 5-year PFS: 30% vs. 14%, p=0.002). Treatment failure occurred in 34 patients; out-of-field failure was dominant (intra-thoracic recurrence 35.3%; extrathoracic recurrence 11.8%), while local failure rate was 5.8%. Conclusion: Salvage RT for recurrent thymoma using high doses and advanced precision techniques produced favorable outcomes, providing evidence that recurrent thymoma is radiosensitive.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.28-35
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• 2002

In cavity flow, the rectangular step generates so strong sound that many researchers have investigated method to suppress the nois during interaction between vortical flow and rectangular forward step. In this study the flow noise from the vortex motion in two-dimentional low Mach number flow past a forward step with various chamfering angle is calculated numerically. Inviscid incompressible discrete vortex model and matched asymptotic expansion(MAE) theory are applied to obtain the inner flow field and the outer noise field. Both source acoustic pressure and sound intensity are obtained with various chamfering height, chamfering angle and initial vortex position. The pressure amplitude is most suppressed when the chamfering angle is between $15^{\circ}C$ and $30^{\circC}$ at the chamfering length of 30% of the step height.

• Journal of Korean Society on Water Environment
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• v.31 no.2
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• pp.94-102
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• 2015

Electro-coagulation experiments were conducted with aluminum (Al) or iron (Fe) electrode in order to determine the optimal electrode material and operation conditions for algae removal. Al electrode showed higher removal rate of algae than Fe electrode because Al flocs have positive surface charges which electrostatically attract algae species having negative surface charges. Removal rate of algae and total phosphorous (T-P) was increased as current density and electrode area increases. It was also found that initial pH with neutral range was optimum for T-P removal by electro-coagulation. Bench-scale continuous flow experiments consisted of electro-coagulation reactor, agitation tank and settling tank were conducted. In electro-coagulation reactor, a large fraction of Al flocs were distributed to scum layer, due to the gas bubbles generated by electrolysis reaction. In agitation tank, most of Al flocs were settled and the optimal mixing intensity was found to be 50 rpm to achieve good settleability. The removal rate of algae was about 90-95%. Additionally, the removal rate of the T-P and COD was observed to be $73.8{\pm}8.0%$ and $75.0{\pm}3.8%$, respectively. Meanwhile, the removal rate of total nitrogen (T-N) was relatively low at only 24%.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.779-787
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• 2021

This study compared the meat quality characteristics, palatability, and histochemical characteristics of low-marbled Hanwoo and Holstein steers of different beef quality grades (1, 2, and 3). No differences were observed in muscle pH_{24 h} and cooking loss between the groups (p>0.05); however, quality grade 1 of Hanwoo steers (HA1) showed a darker muscle surface compared to grade 1 of Holstein steers (HO1) (30.9 vs. 33.9, p<0.05). The HA2 group exhibited a lower value of Warner-Bratzler shear force compared to the HO1 and HO3 groups (60.8 vs. 69.2 and 87.8 N, p<0.001). For sensory quality attributes, steaks from the HA1 group showed higher scores of softness, initial tenderness, and amount of perceptible residue than steaks from the HO1 group (p<0.001). Within the quality grade 2, Hanwoo steers had a higher score of softness compared to Holstein steers (p<0.001). There were no differences in juiciness and flavor intensity between Hanwoo and Holstein steers at the same quality grade (p>0.05). This difference in tenderness attributes between the breeds within the quality grade was associated with morphological traits of muscle bundle, and Hanwoo steers had smaller bundle area (0.37 vs. 0.50 mm², p<0.05) and higher fiber number per bundle (88.2 vs. 121, p<0.05) compared to Holstein steers. Therefore, bundle characteristics of longissimus thoracis muscle can be crucial for explaining factor for the explanation of tenderness variations between different breeds at the same beef quality grade or marbling.

• Korean Journal of Radiology
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• v.23 no.1
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• pp.60-67
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• 2022

Objective: To categorize multiparametric MRI features of Bacillus Calmette-Guérin (BCG)-related granulomatous prostatitis (GP) and discover potential manifestations for its differential diagnosis from prostate cancer. Materials and Methods: The cases of BCG-related GP in 24 male (mean age ± standard deviation, 66.0 ± 9.4 years; range, 50-88 years) pathologically confirmed between January 2011 and April 2019 were retrospectively reviewed. All patients underwent intravesical BCG therapy followed by a MRI scan. Additional follow-up MRI scans, including diffusion-weighted imaging (DWI), were performed in 19 patients. The BCG-related GP cases were categorized into three: A, B, or C. The lesions with diffusion restriction and homogeneous enhancement were classified as type A. The lesions with diffusion restriction and a poorly enhancing component were classified as type B. A low signal intensity on high b-value DWI (b = 1000 s/mm²) was considered characteristic of type C. Two radiologists independently interpreted the MRI scans before making a consensus about the types. Results: The median lesion size was 22 mm with the interquartile range (IQR) of 18-26 mm as measured using the initial MRI scans. The lesion types were A, B, and C in 7, 15, and 2 patients, respectively. Cohen's kappa value for the inter-reader agreement for the interpretation of the lesion types was 0.837. On the last follow-up MRI scans of 19 patients, the size decreased (median, 5.8 mm; IQR, 3.4-8.5 mm), and the type changed from A or B to C in 11 patients. The lesions resolved in four patients. In five patients who underwent prostatectomy, caseous necrosis on histopathology matched with the non-enhancing components of type B lesions and the entire type C lesions. Conclusion: BCG-related GP demonstrated three imaging patterns on multiparametric MRI. Contrast-enhanced T1-weighted imaging and DWI may play a role in its differential diagnosis from prostate cancer.

• The Korean Journal of Pesticide Science
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• v.19 no.2
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• pp.113-118
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• 2015

This study was carried out to develop the economic thresholds for powdery mildew on pepper. To investigate the relationship between powdery mildew incidence degree and yield, experimental plots with ten treatments as initial disease degree were established. Disease intensity exhibited negative and significant correlation with fruit characters like fruit length, fruit diameter, fruit weight. The adverse effect of the disease on these characteristics was low yield, exhibiting significant negative correlation with disease intensity. There existed close correlation between rate of infected leaf area and yields in the plastic house (Chonhatongil: Y = -3.44X+291.09 $R^2=0.73$, Buchon: Y = -2.14X+327.9 $R^2=0.78$). There existed close correlation between rate of infected leaf area and yield loss in the plastic house (Chonhatongil: Y = 2.14X+15.45 $R^2=0.76$ $r=0.87^{**}$, Buchon: Y = 3.44X+114.21 $R^2=0.73$ $r=0.85^{**}$). Control thresholds diseased rate on powdery mildew of pepper was below 3.2 to 7.3% rate of infected leaf area per plant in the plastic house. The economic thresholds for powdery mildew of pepper was below 3.8 to 6.2% rate of infected leaf area per plant in the plastic house.

• Korean Journal of Psychosomatic Medicine
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• v.7 no.2
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• pp.263-273
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• 1999

Headache is a symptom with varied etiologies and extraordinarily frequent. Headaches can be a symptom of another diseases, such as meningitis, subarachnoid hemorrhage or brain tumor, may represent the disease entity itself as the case in migraine. The international Headache Society criteria were the first to distinguish between primary and secondary headache disorders. When evaluating a patient who presents with headache, the physician abviously needs to identify or exclude the myriad conditions that can cause secondary headache and initial diagnostic workup should be considered. If patient meets the criteria for a primary headache disorder, treatment commonly initiated without additional neurodiagnostic tests. The headache type, its associated feature, and the duration and the intensity of the pain attack all can influence the choice of acute therapy in migraine. Pharmacologically, such as NSAIDs, combination analgesics, vasoactive antimigraineous drugs, neuroleptics, antidepressants, or corticosteroids. Other approches to managing headache include a headache diary to identify triggers, biofeedback, relaxation technique and behavioral modification. Daily preventive medication should be considered by his attack frequency and intensity, and maintained for 4 to 6 months. Tension-type headaches are distinguished between episodic and chronic tension-type headache, but physician must make sure that patient is not drug-overuse or independent during symptomatic abortive therapy or preventive medication. The most difficult headache patients to treat are those with chronic daily headache. They often have physical dependency, low frustration tolerance, sleep problems, and depression. So discontinuation of overused medication is crucial. New developments in migraine therapy are broadening the scope of abortive and prophylactic treatment choices available to the physician. The enhanced ease of the use of sumatriptan and DHE will likely increase patient compliance and satisfaction.