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일방향 적층 복합재료 판에서 한 음원에서 발생된 램파의 군속도
이정기,이상호,Lee Jeong-Ki,Rhee Sang-Ho 한국음향학회 2006 韓國音響學會誌 Vol.25 No.3
The elastic waves in a plate are dispersive waves due to the characteristics of Lamb waves. However, S0 symmetric mode is less dispersive in the frequency region below the first cut-off frequency. The wave Propagation velocities vary with the direction in anisotropic plates such as Carbon Fiber Reinforced Plastic (CFRP) Plates. The wave vector direction and energy flow vector direction are same in isotropic plates. However, the wave vector direction same as the phase velocity direction is not in accordance with the energy flow direction same as the group velocity direction in anisotropic plates. In this study. the dispersion curves or the phase velocity from anti-symmetric and symmetric Lamb wave dispersion equation are calculated for unidirectional laminated composite plate. Slowness surface is sketched using phase velocity under the first cut-off frequency. The direction and magnitude of group velocity are corrected with this slowness surface. The measured group velocities are in good agreement with the corrected group velocity curve except near the fiber direction zone which is called the cusp region. 판재를 따라 전파하는 Lamb wave (램파)는 주파수에 따라 속도가 변하는 분산특성을 갖는다. 일반적으로 등방성 재료에서는 파수 벡터 방향과 에너지 흐름 방향은 같아, 파면이 원형을 유지하면서 전파하지만, 복합재료와 같이 이방성재료에서는 파수 벡터와 에너지 흐름 방향이 서로 다르다. 따라서 이방성 재료에서 하나의 속도에서 다른 속도로 전환하려면 방향을 교정해야 하고 이에 따라 크기도 달라지게 된다. 본 연구에서는 복합재료 판재에서 전파하는 램파 분산방정식을 이용하여 대칭, 비대칭 모드의 분산선도를 작성하였고, 각도에 따라구한 위상속도 분산선도에서 얻어진 위상속도 값으로 slowness surface를 구한 후, 이로부터 군속도의 크기와 방향을 교정하였고, 이를 실험적으로 측정한 속도값과 비교하여 서로 일치함을 확인하였다.
이정기(Jeong Ki Rhee),오영진(Yung Jin Oh),조백기(Baik Kee Cho),허원(Won Houh),이교영(Kyo Young Lee),심상인(Sang In Shim) 대한피부과학회 1989 대한피부과학회지 Vol.27 No.5
The papillary eccrine adenoma is a rare benign sweat gland neoplasm charscterized by potentislly locally aggressive clinical course. We report herein a case of papillsry eccrine adenoma in a 28-year-old female who presented single intradermal tumor on the right postauricular ares. Histopathological findings showed dilated ducts containing eosinophilic or keratinous materials and intraluminal papillary rowths,
Laser Doppler Velocimetry를 이용한 Sodium Lauryl Sulfate의 피부자극 측정
이정기(Jeong Ki Rhee),김형옥(Hyung Ok Kim),김정규(Jeung Kyu Kim),김정원(Chung Won Kim) 대한피부과학회 1989 대한피부과학회지 Vol.27 No.2
It is desirable to use more safe, objective, non-invasive method than visual scoring for the evaluation of irritation reaction and determine the optimum eoncentration of sodium lauryl sulfate(SLS) as a positive irritant control in routine patch test. In this study, SLS was applied to the volar forearm of ll non-atopic, healthy volunteers in concentrations of 0.5, 1.0, 2.0, and 5.0% under occlusion for 24h. The blood flow in test sites exposed to SLS was tecorded by laser Doppler velocimetry (LDV). The test sites were scored visually and the skin blood flow was measured at 24h, 48h, and 72h after the application of FiLS. We obtained the following results,' 1. There was a good correlation between visual scoring and skin blood flow using LDV(p = 0.4547). 2. 5.0% SLS could be used as a positive irritant control in routine patch test (p (0,05).
이정기(Jeong Ki Rhee),허동(Dong Houh),김형옥(Hyung Ok Kim),김정원(Chung Won Kim),강석진(Seok Jin Gang) 대한피부과학회 1989 대한피부과학회지 Vol.27 No.6
A 34-year-old female had an unusual case of cellular blue nevus which had behaved in a locally aggressive fashion. The lesion infiltrsted the adjacent soft tissue of left nail bed and extended into deep phalangeal bone. The involved left thumb was partially amputated because complete excision was impossible and we were quite concerned about malignant transformation. Histologically biphasic pattern without cellular atypism, a characteristic features of cellular blue nevus, was shown. About 2 years later, the lesion had not recurred.
이정기(Jeong Ki Rhee),강성범(Sung Bum Kang),조백기(Baik Kee Cho),허원(Won Houh) 대한피부과학회 1988 대한피부과학회지 Vol.26 No.5
We report a case of chronic bullous dermatosis of childhood occurring in a 8-year-old girl, who has multiple, pruritic, tense, vesicobullous eruptions on the both extremities and pelvic region without mucous membrane inuolvement. A skin biopsy revealed subepidermal vesicles infiltrated with many neutrophiles and a few eosinophiles. Direct immunofluorescent study of the perilesional skin demonstrated moderate intensity of linear IgA and to a lesser degree of IgG deposition at the dermoepidermal junction. The skin lesions responded dramatically to oral dapsone therapy, initially 4mg/kg, and taporing to 2mg/kg for 27 days.
이정기(Jeong Ki Rhee),고익준(Ik Jun Ko),김형옥(Hyung Ok Kim),김정원(Chung Won Kim) 대한피부과학회 1989 대한피부과학회지 Vol.27 No.3
Phakomatosis pigmentova.scularis is a disease complex with dermal melanocyto sis such as nevus of Ota, nevus of Ito, or Mongolian spots and extensive hemangiomatous change such as nevus flammeus, which are associated with systemic organ involvement. We report a 23-year-old female, who showed bilateral nevus of Ota and nevus of Ito with widespread nevus flammeus and Mongolian spots since birth. She was also associated with megalocornea due to congenitol glaucoma and cataract.
백승철(Seung Churl Paik),이정기(Jeong Ki Rhee),김시용(Si Yoing Kim),김형옥(Hyung Ok Kim),김정원(Chung Won Kim) 대한피부과학회 1988 대한피부과학회지 Vol.26 No.4
POEMS syndrome is an unusual plasma cell dyscrasia with multisystemie manifestations featuring polyneuropathy, organomegaly, endocrinopsthy, M protein and skin changes. We have seen a 49-year-old woman presenting with hyperpigmentation, hypertrichosis, hyperhidrosis, and taut thickened skin of the extremities as a skin manifestation of this syndrome. We review the literature and report a case.