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.

개선된 중성염 전해공정을 이용한 모의 방사성금속폐기물의 제염

이지훈,육완이,양호연,하종현 대한방사선 방어학회 2002 방사선방어학회지 Vol.27 No.2

원자력발전소에서 주로 발생되는 금속폐기물인 탄소강을 중성염전해질인 1.7M의 황산나트륨(Na₂SO₄)과 질산나트륨(NaNO₃)을 이용하여 기존전해제염과 개선된 전해제염공정의 비교실험을 수행하였다. 양극은 인코넬, 음극은 티타늄으로 하여 상온에서 1시간동안 반응시켜 금속폐기물 모재의 weight loss, 두께변화, 전해질 내 침전물농도, SEM을 이용하여 제염전후의 금속폐기물 표면의 형상을 분석하였다. 실험결과 개선된 전해제염 적용시 전해질 종류별 전류밀도 변화에 따른 실험에서는 전류밀도가 0.1∼0.6A/cm²으로 증가함에 따라 1.7M의 황산나트륨 적용시 금속폐기물 모재의 두께변화는 0.48±0.005∼67.7±0.02um, 1.7M의 질산나트륨 적용시에는 0.06±0.005∼17.7±0.05로 나타나 같은 전류밀도에서 황산나트륨 적용시 금속폐기물 모재의 표면 제염효율이 더욱 높은 양상을 보였다. 또한 전류밀도 0.3 A/cm² 및 1.7M의 황산나트륨의 조건에서 개선된 전해제염 적용 시 9.8±0.01um의 금속폐기물 두께변화를 보여 기존전해제염 적용시인 3.7±0.03um의 금속폐기물 두께변화보다 2배 이상의 표면 제염효과를 보였다. Conventional and modified electrolytic decontamination experiment were performed in the 1.7 M solution of sodium sulfate and sodium nitrate for decontamination of carbon steel as the simulated metal wastes which have been produced in large amounts from nuclear power plants. Anode and cathode were used as inconel and titanium respectively. The reaction time and temperature were 1 hr and 25℃. The analyses were performed of the characteristics such as weight loss and thickness change of metal waste, suspended solid in electrolyte and SEM observation. In modified electrolyte decontamination system with increased current density ranged from 0.1 to 0.6 A/cm², the metal waste showed thickness changes of 0.48±0.005 to 67.7±0.02um in 1.7 M sodium sulfate and those of 0.06±0.005 to 17.7±0.05um in sodium nitrate. Metal waste in modified electrolyte decontamination system showed the thickness change of 9.8±0.01um while it reacted up to 3.7±0.03um in conventional system with 0.3 A/cm² of current density and 1.7 M sodium sulfate. Decontamination efficiencies of modified electrolytic process are much higher than that of conventional electrolytic process when both are applied to metal waste.

Inductive Matching Feed를 이용한 금속용 UHF대역 RFID Tag Antenna 설계

최지훈,양진모 대구대학교 정보통신연구소 2008 情報通信硏究 Vol.5 No.1

In this paper, a novel antenna for UHF-band RFID tag mountable on conductive objects is designed and manufactured. It generates high Q (Quality factor) between antenna and conductive object when general planar RFID tag antenna is mounting on conductive objects. This is because of parasitic capacitors generated between antenna and conductive object and capacitive impedance of RFID chip. This effect has many influence on impedance, frequency, and radiation efficiency of the antenna, so it brings a detection distance reduction. The propose of this paper is minimization of Q effect to improve the bandwidth, and to bring a compact geometry design.. A measured maximum detection distance is 4m when the designed antenna is mounting on metallic surface and a liquid. The impedance bandwidth is 60% at the center frequency(900MHz) and the gain is 4dBi. 본 연구에서는 전도성 물질에 부착 가능한 UHF대역의 RFID (Radio Frequency Identification) Tag 안테나를 설계 및 제작하였다. 일반적인 평면 타입의 RFID Tag 안테나의 경우 전도성 물질에 부착하였을 때, 안테나와 전도성 물질간의 기생 리액턴스 성분이 발생되고, RFID Chip 자체의 큰 허수 임피던스 값에 의해 높은 Q (Quality Factor) 값을 가지게 된다. 이러한 영향은 안테나의 임피던스와 공진 주파수가 변하며 방사효율 또한 변하게 되어 인식거리 저하를 가져온다. 본 연구에서는 Q 값에 의한 영향을 최소화하여 광대역화를 이루고, 안테나 구조를 간단히 하는 설계 방법을 제시하였다. 설계된 안테나를 제작하여 금속 표면 및 액체에 부착하였을 때 측정된 최대 인식 거리가 4m이다. 임피던스 대역폭()은 중심주파수(900MHz)에서 60%의 대역폭을 가졌으며, 이득이 4dBi로 우수한 성능을 나타내었다.

자살 시도에 영향을 미치는 정신사회적 요인

허지원,최광연,이분희,심세훈,양종철,김용구 大韓神經精神醫學會 2007 신경정신의학 Vol.46 No.2

Objectives : A lots of studies have investigated the psychosocial characteristics of suicidal attempters in order to find eff-cient coping strategy and treatment intervention. The purpose of this study was to examine the psychosocial factors affecting the suicide attempt in psychiatric patients. Methods : Two hundred eighty patients who attempted suicide and admitted in the emergency room in 3 university hospitals from December 2003 to May 2006 were recruited in this study. The patients were interviewed using Structured Clinical Inter-view for DSM-IV Axis I disorder (SCID-RV), Lethality of Suicide Attempt Ratings Scale (LSARS) and Risk-Rescue Rating system (RRR). Results : The suicide attempters have psychosocial characteristics of female preponderance, age 20-39, high school in educational level, married in marriage condition, inoccupation, house makers in occupation. Most of attempters used the non-severe methods such as drug ingestion or wrist cutting, and selected home as the place of attempt. The delay until discovery was less than 4 hours for most suicide attempters, and the rate of asking for help directly or dropping clues were high. Major depressive disorder was the most common psychiatric illness among attempters. Conclusions : The present study would be the early stage to explore the risk factor and protect factor of suicidal attempt. This study suggests that the closed observation to potential-suicidal attempter in daily life is critical to protect against the fatal results due to suicidal attempts.

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.

TV의 매체적 속성과 프로그램의 연관성 연구 : TV코미디 프로그램의 공감각적 특성을 중심으로 Focusing on Synesthetic Characteristics of TV Comedy Programs

하효숙,양지윤,홍예진 서강대학교 언론문화연구소 2002 언론문화연구 Vol.18 No.-

해남지역 하천에서의 비점오염원에 관한 연구

송재준,천지훈,서지양 木浦大學校 沿岸環境硏究所 1999 沿岸環境硏究 Vol.16 No.1

It is so difficult to know about the course of non-point source that only few people studying. This is the reason why we did not get good result in water-treatment frequently. Point and non-point source study must be balanced. This report have this intention. Summer is rain season in Korea so we have many problem in water quality. Bad quality originated from agricultural field, non-point source, that flow nutrients, agricultural chemicals, weed chemicals and etc. In this report provide the basic data of non-point source study on river of Haenam Area. Three point that we research is near Bok-pyoung, Kil-ho and Eo-seong bridge at 1999. 7. 5 ∼ 7. 12. Resulted: BOD, COD, SS, T-N, NH₃-N, NO₃-N, T-P, PO₄-P, Alkalinity decrease afterraining, dilution, much amount of water quantity made it. Agricultural section that major non-point source effluent high waste concentration at first stage, but dilution made lower at last. so it is needed that non-point source water storage for improve first stage wastewater at the lower part of a river. And continuous study about non-point source outbreak reason by waste effluent quantity data that made water quality and quantity research after division of the land useness near the river is needed, too.

단면형상변화에 따른 점용접 부재의 에너지흡수 특성

최영민,차천석,김지훈,서현경,양인영 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

The front-end side members of vehicles absorb the most of the energy during the front-end collision. These side members are mostly consist of single hat shape. The side members absorb more energy under axial load if they have higher strength, and stable folding capacity (local buckling). When structural members are subjected to axial loadings, stress is concentrated on their edges. Thus, in this study, the energy absorption characteristics of the member were analyzed according to change of sectional shape for increase of strength. The side members consist of single hat, double hat, single cap and double cap section member. Based on the static test result of these side member, the impact simulation were carried out and compared with test result.

Prevalence of acne in other common dermatologic diseases - results from 18 years database of seoul national university hospital

( Ji Hoon Yang ),( Jungyoon Moon ),( Soo Ick Cho ),( Dae Hun Suh ) 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.2

Background: Acne is a common inflammatory skin disease associated with microbes such as Propionibacterium acnes. Inflammatory processes in acne may share some similarity to other inflammatory skin diseases. Objectives: The co-morbidity of acne with these diseases is worth investigating. Methods: We compared the prevalence of acne in atopic dermatitis, psoriasis, urticaria and alopecia areata (AA) from 2000 to 2017 in Seoul National University Hospital. The criteria of the diseases were based on the ICD-10 code and concurrent treatment. The patients who met the criteria were selected. Results: A total of 18,742 patients (AD: 5,597, psoriasis: 3,565, urticaria: 8,151, AA: 1,429) were selected from the database. The prevalence of acne was 8.8% in AD, 2.2% in psoriasis, 4.2% in urticaria, and 5.5% in AA. After adjusting age and sex, the odd ratio of acne in AD was 1.419 (95% confidence interval (CI): 1.219-1.652, p<0.001) and in psoriasis was 0.574 (95% CI: 0.446-0.738, p<0.001), compared to urticaria. Conclusion: This study showed the difference in the prevalence of acne in AD and psoriasis. There is a possibility that inflammatory process involved in there diseases are different each other.

A case of syphilic gumma: a great masquerader

( Ji Hoon Yang ),( Jungyoon Moon ),( Hyun-sun Yoon ),( Soyun Cho ),( Hyun-sun Park ) 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.1

A syphilitic gumma is now extremely rare type of tertiary syphilis, which is easy to be misdiagnosed and requires high suspicion index. A 48-year-old woman presented with a painless ulcerated plaque on her face for 2 months. She was previously healthy and denied trauma and skin cancer history. Physical examination showed a 4×4 cm crater-shaped plaque with crusts and oozing. Provisional diagnosis included pyoderma gangrenosum and squamous cell carcinoma. Skin biopsy demonstrated extensive necrosis and large areas of granulomatous inflammation within the dermis, including numerous multinucleated giant cells and marked lymphoplasmacytic infiltrates. A rapid plasma regain test was reactive. A human immunodeficiency virus test was negative. Only then did the patient mention that she was inadequately treated for syphilis 20 years ago. Taken together, she was finally diagnosed with a syphilitic gumma. Further work up including cerebrospinal fluid analysis did not reveal any evidence of internal organ involvement. The lesion was significantly improved after three intramuscular injections of 2.4 million units of penicillin G.