탄소섬유/고인성 에폭시 수지 적층판의 모드Ⅱ 파괴인성 평가

심재기,양인영,김영남,조규재,김지훈 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.1

본 연구에서는 탄소섬유/고인성 EPOXY의 일방향 CFRP적층시험편에 대해 정적 ENF 시험 및 스프릿홉킨손봉법에 의한 동적 ENF시험을 하여 일방향 CFRP 적층판의 모드Ⅱ층간파괴인성치를 측정된 하중응답, 반력봉 반력의 J-적분과 시험편의 변위해석을 통하여 평가하였다 실험결과, 준정적 변위속도 δ = 5 × 10 근방에서 하중 최저점에서부터 하중의 진동이 발생하기 시작함을 알 수 있었으며, 또한 최저 측정점에서 하중점 변위속도의 증가와 더불어 동적 층간파괴 인성치가 증가함을 알 수 있었다. In this paper, an investigation was performed on the dynamic interlaminar fracture toughness of CFRP(carbon fiber reinforced plastics) composite laminates. Composite laminates used in this experimentation are CF/high toughness Epoxy Resin composite laminated plates. In the experiments, Split Hopkinson's Bar(SHPE) test was applied to dynamic and notched flexure test. The mode Ⅱ fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-integral with the measured impulsive load and reactions at the supported points. As an experimental results, Loading vibrations are generated when quasi-static displacement velocity, δ becomes 5×10 from the lowest loading point. It is thought that the dynamic fracture toughness of specimens(CF/EPOXY) with the increase of displacement velocity becomes a little greater at a measuring point within the range of measurement.

인터리브가 삽입된 CFRP 적층판의 층간파괴 인성평가

김지훈,강태식,한길영,김재열,심재기 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.4

In this paper, an investigation was performed on the dynamic interlaminar fracture toughness of CFRP(carbon fiber reinforcement plastics). Specimens used in this experiment are CF/PEEK laminated plates. In this experiments, Split Hopkin-son's Bar(SHPE) test was apply to dynamic and notched flexure test. The mode II fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-integral with the measured impulsive load and reac-tions at the supported points. As an experimental result the vibration amplitude of [0˚_10/F_4/0˚_10] laminates appear more than that of [0˚_10/F_2/0˚_10] laminates for the J-integral and displacement velocity at a measuring point. Also, it is thought that the dynamic fracture toughness of two kind specimen(CF/PEEK) with the in crease of displacement velocity becomes great at a measuring point with in the range of measurement.

수지함량에 따른 CFRP 적층판의 층간파괴 인성평가

김지훈,양인영,심재기 한국공작기계학회 2003 한국생산제조학회지 Vol.12 No.4

This research work has been carried out for finding J-integral in modeⅡ of CFRP (carbon fiber reinforced plastics) laminate plates based on the classical bar theory in dynamic conditions with considerations of the effect of inertia forces, eventually to lead to finding the dynamic inter-layer fracture toughness. Dynamic inter-layer fracture toughness was found by a self-made EFN (End Notched Flexure) experimental apparatus using Split Hopkinson's BAR (SHPB), and also observed the variation of the fracture toughness having different resin contents and fiber arrangements of CFRP specimen ([0˚_3/90˚_3/0˚_6/90˚_3/0˚_3], [0˚_20], [0˚_5/90˚_10/0˚_5]). As an experimental result, in either cases of quasi-static or dynamic load condition, the critical load and the inter-layer fracture toughness increased sharply depending on the increase of resin contents. Therefore, it could, be concluded that the effect by resin contents is the major factor determining the inter-layer fracture toughness in the CFRP laminate plates.

유기마이크로파티클 시스템에의한 보류특성 변화

권진,이근수,이지훈,심지영,조병묵 한국공업화학회 2004 응용화학 Vol.8 No.1

Todays, papermaking is change to poor condition and importance of retention has been increased. Therefore microparticle system has been developed and used very widly which provides the retention mechanism by cationic polymer and high charged micoparticle. In this study, we compared the retention efficiency of traditional microparticle(bentonite) and organic microparticle.

저장 기간에 따른 사과의 품질특성과 항산화 활성 변화

진소연,심기현,이은지,구혜진,김명현,한영실,박정수,김용훈,Jin, So-Yeon,Sim, Ki Hyeon,Lee, Eun Ji,Gu, Hae Jin,Kim, Myung Hyun,Han, Young Sil,Park, Jung Su,Kim, Yong-Hoon 한국식품영양학회 2014 韓國食品營養學會誌 Vol.27 No.6

$20^{\circ}C$에서 15일 동안 저장기간별 사과의 변화를 살펴본 결과는 다음과 같다. 사과의 중량과 수분은 저장기간 경과에 따라 점차적으로 감소하는 결과를 보였으며, 사과의 저장 중 가용성 고형물 함량은 저장 4일차까지 최고치로 증가하였다가 서서히 낮아지는 경향을 나타냈다. 사과의 저장 중 유기산 산도는 저장 5일차에 급격히 감소하다가 완만히 감소하였으며, pH는 저장기간에 따라 완만히 증가하는 경향을 나타내었다. 저장 중 사과 껍질의 색상을 측정한 결과, L값은 저장기간에 따라 서서히 증가하였으며, a값은 저장 3일까지 감소하였고, 저장 5일에 증가되었다가 그 이후 점진적으로 감소하였다. b값은 저장 6일에 최저치를 보인 후 서서히 증가하는 경향을 보였다. 사과의 조직감을 측정한 결과, 저장기간이 증가됨에 따라 사과의 경도는 전반적으로 감소하였다. 저장 기간에 따른 사과의 총 페놀과 총 플라보노이드 함량을 측정한 결과, 총 페놀 함량은 저장 기간이 길어질수록 감소하는 경향이 나타났으며, 저장 3일차에서 저장 4일차에 큰 폭 감소하였다. 총 플라보노이드의 변화 결과, 1일차에 비교적 크게 감소하였고, 실험 7일차에서 8일차 사이에 급격히 감소하였다. 저장 기간에 따른 사과의 DPPH 전자공여능 측정결과, 저장기간이 증가할수록 DPPH 전자공여능은 감소하였으며, Vit. C 함량의 경우 저장 기간이 길어질수록 감소하였는데, 특히 저장 4일차에 비교적 크게 감소하였다. 사과의 관능평가 수행 결과, 저장기간이 경과함에 따라 외관의 좋은 정도는 0일차에 6.75에서 15일차 2.83으로 크게 감소하였으며, 신맛의 좋은 정도는 저장 기간에 따라 유의적인 차이를 보이지 않았으나, 전반적으로 감소하는 경향이었다. 단맛의 좋은 정도와 아삭함의 좋은 정도에서는 0일차에 각 6.25, 5.33으로 가장 높았으며, 15일차에 각 3.92, 2.83으로 유의적으로 감소하였다. 종합적인 기호도에서는 7일차와 8일차 사이에 5.00에서 3.50으로 비교적 큰 폭 감소하였으며, 15일차에 2.00으로 저장 기간에 지남에 따라 유의적으로 감소하였다. 이상의 실험결과, 사과 저장 시 3~4일차에 유의적인 차이를 보였으며, 저장 8일 이후에는 모든 항목에 있어 측정감이 크게 변화하는 경향을 나타내었다. 따라서 $0{\sim}1^{\circ}C$에서 장기 저장한 사과를 $20^{\circ}C$ 전후에서 저장 및 판매할 경우, 최고의 품질을 위해서는 3일 내에 판매할 것을 권장하며, 8일 이내에 재고를 소진할 수 있도록 유통 기간을 조정하는 것이 바람직할 것으로 사료된다. This study was performed in order to compare the changes in Korean apples' qualities and antioxidant activity when stored at room temperature, $20^{\circ}C$, for fifteen days. The results showed that the weight, moisture content, soluble solid content, acidity, and hardness levels decreased as the storage period increased. However, pH and color value L increased as the storage period increased. Total phenol contents, total flavonoids contents, DPPH free radical scavenging activity, and vit. C contents of apples significantly decreased with increased storage period. Sensory parameters, such as appearance, sweetness, sourness, crunchiness, and overall acceptability of apples, also decreased as the storage period increased. Based on these results, if, the apple are being stored around $20^{\circ}C$, then, to have the highest quality, the apples should be sold within three days, We also suggested that it is desirable not to store the apples fore more than eight days.

Treatment of melasma by low fluence 1064nm Q-switched Nd:YAG laser

( Ji Hoon Sim ),( Jung Eun Kim ),( Hong Ki Cho ),( Euy Hyunchung ),( Young Lip Park ),( Moon Kyuncho ),( You In Bae ) 대한피부과학회 2012 대한피부과학회 학술발표대회집 Vol.64 No.3

Association between De Ritis ratio and intraoperative blood transfusion in patients undergoing surgical clipping of unruptured intracranial aneurysms: a single center, retrospective, propensity score-matched study

Sim Ji-Hoon,Kim Chan-Sik,Ha Seungil,Kim Hyunkook,박용석,Kim Joung Uk 대한마취통증의학회 2024 Korean Journal of Anesthesiology Vol.77 No.2

Background: Although elective surgery for unruptured intracranial aneurysms (UIA) has increased, few studies have evaluated the risk factors for transfusion during UIA surgery. We evaluated the association between the preoperative De Ritis ratio (aspartate transaminase/alanine transaminase) and the incidence of intraoperative transfusion in patients who had undergone surgical UIA clipping. Methods: Patients who underwent surgical clipping of UIA were stratified into two groups according to the preoperative De Ritis ratio cutoff levels (< 1.54 and ≥ 1.54), and the propensity score (PS)-matching analysis was performed to compare the incidence of intraoperative transfusion. Logistic regression analyses were performed to determine the risk factors for intraoperative transfusion. Net reclassification improvement (NRI) and integrated discrimination improvement (IDI) analyses were performed to verify the improvement in the intraoperative transfusion predictive model upon addition of the De Ritis ratio. Results: Intraoperative transfusion incidence was 15.4% (77/502). We observed significant differences in the incidence of intraoperative transfusion (16.2% vs. 39.7%, P = 0.004) between the groups after matching. In the logistic regression analyses, the De Ritis ratio ≥ 1.54 was an independent risk factor for transfusion (odds ratio [OR]: 3.04, 95% CI [1.53, 6.03], P = 0.002). Preoperative hemoglobin (Hb) value was a risk factor for transfusion (OR: 0.33, 95% CI [0.24, 0.47], P < 0.001). NRI and IDI analyses showed that the De Ritis ratio improved the intraoperative blood transfusion predictive models (P = 0.031 and P = 0.049, respectively).Conclusions: De Ritis ratio maybe a significant risk factor for intraoperative transfusion in UIA surgery.

A case of cutaneous metastasis to scalp from Lung angiosarcoma (초)

( Ji Hoon Sim ),( Gang Mo Lee ),( Jung Woong Shin ),( Hyung Dong Kim ),( Sang Hoon Lee ),( Kyu Uang Whang ) 대한피부과학회 2011 초록집 Vol.49 No.10

Vulvar Skin Metastasis of Lung Squamous Cell Carcinoma

Ji Hoon Sim,Jung Eun Kim,이상훈,Moon Kyun Cho,Jong Suk Lee,이성열 대한피부과학회 2011 Annals of Dermatology Vol.23 No.-

In this study, we examined a case where lung cancer metastasized to the vulvar area. A 79-year-old woman that was a heavy smoker was referred to our department with a short (two-week) history of dyspnea, and with a painful nodule on her right labium majora, which she had noticed almost three years earlier. Histopathologically, the specimen appeared as a poorly differentiated squamous cell carcinoma. The chest X-ray, chest computerized tomography scan, and percutaneous transthoracic needle biopsy via bronchoscopy revealed squamous cell carcinoma in the right upper lobe of the lung. Based on these clinical and histopathological findings, we concluded that her condition was skin metastasis at the right labium majora from the lung cancer, which occurs very rarely. (Ann Dermatol 23(S2)S179∼S181, 2011)

Vulvar skin metastasis of Lung squamous cell carcinoma (초)

( Ji Hoon Sim ),( Han Eul Lee ),( Gun Hong Lee ),( Moon Kyun Cho ),( Young Lip Park ),( Sung Yul Lee ) 대한피부과학회 2011 초록집 Vol.49 No.10