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Effect of Mn and C on Age Hardening of Fe–Mn–Al–C Lightweight Steels
Sung‑Won Park,Jun Young Park,Kyong Mox Cho,Jae Hoon Jang,Seong‑Jun Park,Joonoh Moon,Tae‑Ho Lee,Jong‑Ho Shin 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.3
The effects of Mn and C content on the age hardening of Fe–Mn–Al–C lightweight steels, which have austenitic or duplex(austenite and ferrite) microstructures, were investigated. An increase in Mn content induced a delay of the age hardeningthat is caused by the formation of intra-granular κ-carbides. In order to interpret the effect of Mn content, first-principlescalculations were conducted using the supercells of Fe24Al8C8,Fe24Al8C7,Fe24(Al7Mn)C8, and Fe24(Al7Mn)C7. The calculationsshowed that an increase in Mn content could be the source of the delay of the intra-granular κ-carbide formation bysuppressing C atom’ occupation of the vacancy at the body-centered site of L12. An increase in C content accelerated theformation of intra-granular κ-carbides, which induced the intense age hardening, and coarse inter-granular κ-carbides, whichresulted in significant decrease in impact absorbed energy due to inter-granular fracture.
Clinical and cytogenetic analysis of 10 cases with cutaneous mosaic dyspigmentation
( Sung-min Park ),( Dongyoung Rho ),( Woo-il Kim ),( Min-young Yang ),( Tae-wook Kim ),( Hyun-joo Lee ),( Gun-wook Kim ),( Hoon-soo Kim ),( Byung-soo Kim ),( Moon-bum Kim ),( Hyun-chang Ko ) 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.2
Background: Cytogenetic studies often reveal chromosomal mosaicism in cases of congenital pigmentary disorders like Hypomelanosis of Ito and linear and whorled nevoid hypermelanosis. However, limited data exist in Korean literatures. Objectives: To investigate the characteristics and cytogenetic profile of patients with mosaic dyspigmentation. Methods: Patients with mosaic dyspigmentation without preceding inflammatory lesions between 2016 and 2017 at Pusan National University Yangsan Hospital were included. Clinical features and extracutaneous manifestations were investigated. Karyotyping of fibroblasts from lesional and normal skin was done. Results: Five boys and 5 girls aged from 11 months to 8 years were enrolled. Seven patients (70%) exhibited hypopigmentation, 2 patients (20%) exhibited hyperpigmentation, and 1 patient (10%) exhibited a combination of hyperpigmentation and hypopigmentation. Extracutaneous manifestations were found in 5 patients (50%); musculoskeletal abnormality in 5 patients, and ophthalmological abnormality in 1 patient. One patient had musculoskeletal, neurologic, and endocrinologic abnormalities. Cytogenetic analyses showed mosaic karyotype in 2 patients. Conclusion: Cutaneous mosaic dyspigmentation could be associated with extracutaneous manifestatations, and it may result from karyotypic abnormality. Therefore, karyotyping from skin fibroblasts could be helpful to understand the underlying genetic abnormalities.
Cutaneous sarcoidosis caused by polymethylmethacrylate microspheres
( Sung Min Park ),( Jeong Min Kim ),( Gun Wook Kim ),( Je Ho Mun ),( Margaret Song ),( Hoon Soo Kim ),( Byung Soo Kim ),( Moon Bum Kim ),( Hyun Chang Ko ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.1
Various fillers are currently used for correction of cosmetic defects or soft tissue augmentation. The fillercomposed of polymethylmethacrylate (PMMA) microspheres suspended in a degradable bovine collagen solution, is used as a microimplant for the treatment of wrinkles because of its long-lasting effect. Herein, we report a case of cutaneous sarcoidosis after filler injections. A 51-year-old man presented with a 10-month history of erythematous to violaceous indurated plaques on the forehead, nose and chin. He had received Artecoll® injections at these sites 2 years ago. Histopathologic findings were non-caseating granulomas surrounded by a paucity of lymphocytes. Numerous empty vacuolar structures with various sizes were observed in granulomas. Reticulum fiber stain revealed a network of fibers surrounding and permeating the granulomas. Laboratory investigations, including complete blood count, liver, renal function test, urinalysis, and angiotensin converting enzyme were unremarkable. No evidences of systemic involvement were identified on ophthalmologic examination and imaging studies. Sarcoidosis is a granulomatous disorder of unknown cause. It has been hypothesized to be an abnormal immune reaction to various antigens, resulting in inflammatory response showing granuloma formation. This case represents that the PMMA microspheres could act as a stimulus for the development of the cutaneous sarcodosis in susceptible patients.
( Sung Min Park ),( Jeong Min Kim ),( Gun Wook Kim ),( Je Ho Mun ),( Margaret Song ),( Hoon Soo Kim ),( Byung Soo Kim ),( Moon Bum Kim ),( Hyun Chang Ko ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.1
Cutaneous vascular lesions can occur sporadically, and be a rare cutaneous manifestation of diseases. The molecular pathway involved in vasculogenesis has begun to be identified through genetic analysis of hereditary vascular malformation syndromes. A 19-month-old male infant presented with multiple scattered erythematous patches on his neck, trunk, and extremities. Skin biopsy from erythematous patch revealed slightly dilated, thin walled vessels in the upper dermis. He experienced two myoclonic seizures by 12 months of age. Developmental delay was identified on developmental assessment, but no abnormal findings were detected on brain MRI. Whole-genome cytogenetic array comparative genomic hybridization (aCGH) analysis revealed microdeletion of 5q14.3. The patient’s phenotype of dermatologic and neurologic abnormalities constitutes a 5q14.3 neurocutaneous syndrome due to the deletion of RASA1 and MEF2C. Hereditary capillary malformations with/without arteriovenous malformations are known to be associated with mutation in RASA1, located on the long arm of chromosome 5. Several cases with 5q14.3 microdeletion showing mental retardation, epilepsy, cerebral malformations have been reported and MEF2C is considered as a candidate gene in those phenotype. To our knowledge, this is the 1st report of 5q14.3 neurocutaneous syndrome with multiple capillary malformations in Korean literature.
Sang-Hoon Kang,Se-Jin Park,Moon-Key Kim 대한구강악안면외과학회 2020 대한구강악안면외과학회지 Vol.46 No.1
Objectives: The discontinuation of bisphosphonate (BP) treatment before tooth extraction may induce medication-related osteonecrosis of the jaw (MRONJ). Whether the long-term discontinuation of BP treatment before tooth extraction affects the risk of developing MRONJ after tooth extraction or whether extended drug holidays induce systemic side effects remains unclear. The present study assessed the incidence of MRONJ among patients who underwent tooth extraction and did not discontinue BP therapy prior to the procedure. Materials and Methods: Patients were classified according to whether or not they discontinued BP therapy before tooth extraction. Differences in the incidence of MRONJ after tooth extraction were compared between the two groups using the chi-squared test. Results: The BP-continuation (BPC) and BP-discontinuation (BPDC) groups included 179 and 286 patients, respectively. One patient in the BPC group and no patients in the BPDC group developed MRONJ (P =0.385). The patients in the BPDC group stopped receiving BP therapy at a mean of 39.0±35.5 months prior to tooth extraction. Conclusion: The possibility of pre-existing MRONJ in the extraction area must be considered during the extraction procedure. Routine discontinuation of BP medications for several months before the extraction procedure should be carefully considered, as evidence of its efficacy in reducing the development of post-extraction MRONJ is limited.
Cutaneous epithelioid hemangioendothelioma treated with Mohs micrographic surgery
( Sung Min Park ),( Jeong Min Kim ),( Gun Wook Kim ),( Margaret Song ),( Hoon Soo Kim ),( Hyun Chang Ko ),( Byung Soo Kim ),( Moon Bum Kim ),( Je Ho Mun ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.1
Epithelioid hemangioendothelioma (EHE) is a rare soft tissue vascular tumor, first described by Weiss and Enzinger in 1982. Due to its potential for metastasis and mortality, EHE is currently classified as a fully malignant tumor. Currently, the treatment of choice for EHE is complete surgical resection. So far, none of EHE was treated by Mohs micrographic surgery (MMS) in the literature. A 47-year-old woman presented with a 1-year history of a solitary, ulcerated plaque on the left postauricular region. Histopathologic examination revealed infiltration of oval to polygonal tumor cells with eosinophilic cytoplasm and large vesicular nuclei into the deep dermis. Tumor cells formed intracytoplasmic vacuoles that contain erythrocytes. Immunohistochemical study was positive for vimentin, CD10, CD31 and smooth muscle actin. Based on the histopathologic findings, a diagnosis of cutaneous EHE was made. To maximize cure rate and minimize loss of normal surrounding skins, we performed MMS under local anesthesia. The tumor was removed successfully, and there have been no evidence of local recurrence or distant metastasis during a subsequent 1-year follow-up. To our knowledge, this is the first report of a cutaneous EHE treated with MMS. We suggest MMS can be a good treatment option for cutaneous EHE.
Tufted angioma with localized hyperhidrosis
( Sang Jin Cheon ),( Jeong Min Kim ),( Gun Wook Kim ),( Je Ho Mun ),( Margaret Song ),( Hoon Soo Kim ),( Byung Soo Kim ),( Moon Bum Kim ),( Hyun Chang Ko ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.1
Tufted angioma is a rare benign vascular tumor that mostly appears during infancy or early childhood, usuallyinvolving the neck and trunk. The precise mechanism of the vascular proliferation is uncertain. Microscopically, multiple cellular lobules extending from the papillary dermis to the subcutaneous fatty tissue with a cannonball pattern are characteristic features of tufted angioma. A 6-months-old male infant presented with localized well-defined erythematous patch on left chest. There wasa complaint of increased sweating over the lesion occasionally. On the basis of this clinical feature, differential diagnosis of eccrine angiomatous hamartoma should be considered. On histopathological finding, rounded, oval or elongated lobules of closely packed capillaries were scattered in dermis and superficialsubcutis. Each lobules were composed of poorly canalized capillaries and increased number of eccrine glands were seen in proximity of vascular tuft. The diagnosis of tufted angioma was made by distinctive histopathologic findings. Although some cases of tufted angioma with focal hyperhidrosis were reported in literatures, it``s been rare todemonstrate numerous eccrine glands proliferation in these cases. So this case will be helpful in understanding why tufted angioma can accompany focal hyperhidrosis.
ANALYSIS OF PRESTRESSED CONCRETE CONTAINMENT VESSEL(PCCV) UNDER SEVERE ACCIDENT LOADING
SANG HOON NOH,IL HWAN MOON,JONG BO LEE,JONG HAK KIM 한국원자력학회 2008 Nuclear Engineering and Technology Vol.40 No.1
This paper describes the nonlinear analyses of a 1:4 scale model of a prestressed concrete containment vessel (PCCV) using an axisymmetric model and a three-dimensional model. These two models are refined by comparison of the analysis results and with testing results. This paper is especially focused on the analysis of behavior under pressure and the temperature effects revealed using an axisymmetric model. The temperature-dependent degradation properties of concrete and steel are considered. Both geometric and material nonlinearities, including thermal effects, are also addressed in the analyses. The Menetrey and Willam (1995) concrete constitutive model with non-associated flow potential is adopted for this study. This study includes the results of the predicted thermal and mechanical behaviors of the PCCV subject to high temperature loading and internal pressure at the same time. To find the effect of high temperature accident conditions on the ultimate capacity of the liner plate, reinforcement, prestressing tendon and concrete, two kinds of analyses are performed: one for pressure only and the other for pressure with temperature. The results from the test on pressurization, analysis for pressure only, and analyses considering pressure with temperatures are compared with one another. The analysis results show that the temperature directly affects the behavior of the liner plate, but has little impact on the ultimate pressure capacity of the PCCV.