• KEPCO Journal on Electric Power and Energy
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• v.6 no.1
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• pp.41-47
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• 2020

The contribution of damage mechanisms to failure of steam turbine casing made of Cr-Mo-V steel was investigated. Creep-fatigue interaction on the HP side corner of turbine casing was revealed as the root cause of the catastrophic failure performed by metallurgical analysis. The steady-state pressure and transient thermal stress were analyzed based on the actual operating condition of the thermal plant. Damage of creep-fatigue interaction to crack initiation was evaluated with multiaxial effects. The contribution ratio of creep and fatigue to the crack initiation was estimated to 3:1. Temporary geometrical correct action with repair weld was executed. For long-term operation, design improvement of casing equipment for creep resistance should be needed.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.301-308
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• 2010

Quest for reliability of hydraulic runners is a concern for all mature electricity producers. The fatigue damage caused by dynamics loads is frequently the root cause of runner failure. This paper presents the damage tolerance approach based on fracture mechanics as the method chosen by Alstom and Hydro-Qu$\acute{e}$bec to predict effects of damage on runner lifetime and consequently to be use as a design method. This is sustained by a research on fracture mechanics properties of runner materials and by recommendations on the strategy to define a safety margin for design. The acquired knowledge permits to identify potential improvement of the runner lifetime without significant cost increase, like being more specific on some chemical composition or heat treatment.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.2
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• pp.127-132
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• 2013

Traumatic injuries to immature permanent teeth are common and the results can be destructive. Although Hertwig's epithelial root sheath is usually sensitive to trauma, it may resist damage from trauma thereby retaining its vitality and continuing to calcify a root under favorable conditions. This case report describes two cases of trauma to immature permanent incisors. The first case presents an avulsed maxillary central incisor which has been replanted. The other case shows completely avulsed mandibular central incisors which have not been replanted. However, both cases subsequently show continued growing roots separated from the main roots. This report highlights the ability of the immature pulp tissue to continue to form dentin and the robustness of Hertwig's epithelial root sheath to initiate root development despite a traumatic injury.

• Korean journal of applied entomology
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• v.46 no.1 s.145
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• pp.169-173
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• 2007

Root-knot nematode damage was found on yam, Dioscorea bulbifera in Andong Korea. From the root-knots, female nematodes were isolated and subjected to DNA sequence analysis. Sequence of cytochrome oxidase subunit II (COII) was analyzed from the genomic DNA of the isolate. COII locus size and sequence of the nematode isolate were similar to those of Meloidogyne javanica or M. incognita. However, an analysis of HinfI restriction site, a species-specific character between these two species, showed that the isolate did not match to either M. javanica or M. incognita.

• The Korean Journal of Pain
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• v.11 no.1
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• pp.127-129
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• 1998

Intractable chest and abdominal wall pain responds well to root surgery. But it is better to perform this procedure less invasively with less complications. Cryoanalgesia has been developed to relieve several neurogenic pain without causing irrversible nerve damage. Well-selected percutaneous cryoablative procedure could be one of the technique of choice for some chronic pains because it has the advantage of easy application without any remarkable side effect. We did percutaneous cryoneurolysis of the spinal nerve root at the thoracic level to treat one patient with severe cancer pain on the chest wall(T4, 5, and 8 dermatomes) after successful percutaneous radiofrequency T6 and T7 posterior root rhizotomy. This procedure was performed under fluoroscopic guidance. We advanced 2 mm cryoprobe to the posterior, superior aspect of vertebral foramen on lateral view until the patient felt paresthesia. 3 times of 2 minutes freezing was applied to each spinal nerve root. The patient got immediate pain relief without any side effect.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.115-120
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• 1989

Universal characteristics of ginseng replanting problems appeared to be decrease in root yields due to root rot and inhibition of root growth. Incitants of ginseng replanting problems have not been clearly elucidated, however, it appeared to be a complex phenomenon with several pathogenic soil microorganisms and environmental changes in the soil due to decomposition of ginseng debris such as rootlets and shoots. Decomposition of ginseng debris may cause direct or indirect damage to the root. The effect of conventional fungicide on the control of the problems has not been recognized. However, it has been suggested that treatment with soil fumigants may solve the problems. Meanwhile paddy-rice and ginseng rotation system appeared to be the best way of solving the problems so far.

• Journal of Environmental Science International
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• v.5 no.6
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• pp.813-826
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• 1996

The toxic effects of aluminium (Al) on growth, chlorophyll content, $\delta-aminolevulinic$ acid dehydratase (ALAD) activity and anatomy of root and shoot were investigated in 7-day-old azuki bean (Vigna angularis) seedlings. Significant depressions in root elongation was observed in the low concentrations of Al (50, 100 $\muM)$ and increasing Al concentrations caused a sharp decline of root and shoot growth. The degree of inhibition was dependent upon Al supply. Exposure to 50 $\muM$ Al or more inhibited root elongation within 1 day. In the 50 $\muM$ Al treatments, a recovery of root growth was seen after 7 days exposure. In contrast, lateral root initials was little affected by Al exposure. Al toxicity symptoms and growth responses were more well developed in the roots than in the shoots. Analysis of Al localization in root cells by hematoxylin stAlning showed that Al entered root apices and accumulated in the epidermal and cortical cells immeadiately below the epidermis. There was a good positive correlation between the level of chlorophyll and ALAD activity. Increasing Al concentrations caused a decrease in total chlorophyll contents, accompanied by proportional changes in ALAD activity, suggesting a cootr-dinated reduction of a photosynthetic machinery. Al exerted specific influence on the morphology of root ann shoot. At higher concentrations of Al the roots induced drastic anatomical changes. The epidermal cells were disorganized or destructed while the cortical cells exhibited distortion of cell shape and/or disintegration. The diameter of root and transectional area of cortical cells decreased considerably with Al treatment. In the shoot Al also enhanced reduction of diameter of shoot and cell size. Gross anatomy of leaves treated with Al did not differ significantly from the controls, except for fewer and smaller chloroplast. Our results indicate that toxic effect of Al appear to be manifested primarily in roots and secondarily on shoots, and changes in root morphology are related to changes in the root growth patterns. Results are further discussed in re181ion to the findings in other plant species, and it is concluded that Al causes morphological, structural and, presumably, functional damage to the roots of the species investigated.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.154-163
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• 2018

Not only South Korea but also Global world show that the frequency and damages of large-scale natural disaster due to the rise of heavy rain event and typhoon or hurricane intensity are increasing. Natural disasters such as typhoon, flood, heavy rain, strong wind, wind wave, tidal wave, tide, heavy snow, drought, earthquake, yellow dust and so on, are difficult to estimate the scale of damage and spot. Also, there are many difficulties to take action because natural disasters don't appear precursor phenomena However, if scale of damage can be estimated, damages would be mitigated through the initial damage action. In the present study, therefore, wind wave damage estimation functions for the western coastal zone are developed based on annual disaster reports which were published by the Ministry of Public Safety and Security. The wind wave damage estimation functions were distinguished by regional groups and facilities and NRMSE (Normalized Root Mean Square Error) was analyzed from 1.94% to 26.07%. The damage could be mitigated if scale of damage can be estimated through developed functions and the proper response is taken.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.4
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• pp.521-527
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• 2018

In dental trauma, reattachment of the original tooth fragment improves the reproduction of original tooth shape, texture, color, and radiolucency; thus, it provides good aesthetics. A 9-year-old boy was referred due to complicated crown-root fracture of the maxillary right central incisor. Although it had poor prognosis due to severe coronal damage and subcrestal fracture, reattachment of the tooth fragment was chosen due to the patient's age. One-visit apexification with mineral trioxide aggregate (MTA) was performed, followed by osteotomy and reattachment of the tooth fragment with post placement. Regular observation revealed no clinical signs or symptoms and no radiologic complications.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.426-437
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• 2023

Objective : To investigate the efficacy and safety of the posterior endoscopic cervical foraminotomy (PECF) using ultrasonic osteotome for the treatment of cervical osseous foraminal stenosis, focusing on introduction of the advantages of ultrasonic osteotome in partial pediculectomy and ventral osteophyte resection in PECF. Methods : Nineteen patients with cervical osseous foraminal stenosis who underwent PECF using ultrasonic osteotome in our institution between April 2018 and April 2021 were enrolled in this study. All the patients were followed up more than 12 months. The patients' medical data, as well as pre- and postoperative radiologic findings were thoroughly investigated. The visual analogue score (VAS), Japanese Orthopaedic Association (JOA) score, cervical dysfunction index (Neck disability index, NDI), and modified MacNab criteria were used to assess the surgical efficacy. Results : All the patients were successfully treated with PECF using ultrasonic osteotome. The pre- and postoperative VAS, NDI, and JOA scores were significantly improved (p<0.05). According to the modified MacNab criteria, 17 patients were assessed as "excellent", two patients were assessed as "good" at the last follow-up. There was no dura tear, nerve root damage, incision infection, neck deformity, or other complications. Conclusion : Adequate nerve root decompression can be accomplished successfully with the help of ultrasonic osteotome in PECF, which has the advantage of reducing the probability of damage to the nerve root and dura mater, in addition to the original merits of endoscopic surgery.