셰일저류층의 다단계 수압파쇄에서 응력그림자 효과를 고려한 균열형태 분석

유정민(Jeong-min Yoo),박혜민(Hyemin Park),왕지훈(Jihoon Wang),성원모(Wonmo Sung) 한국가스학회 2021 한국가스학회지 Vol.25 No.1

투과성이 낮은 셰일층에서의 다단계 수압파쇄 시, 파쇄단계 간의 서로 근접한 균열로 인해 지층 간 응력간섭이 발생하는 ‘응력그림자효과’가 나타날 수 있다. 이로 인해 균열의 전파 방향성이 변화하거나 비정형적인 형태의 균열이 발생하게 된다. 본 연구에서는 응력그림자효과의 영향에 따른 수압파쇄 균열형태와 생산성을 분석하고자 상용 수압파쇄 시뮬레이터 full-3D모델인 ‘GOHFER’를 사용하였다. 균질한 저류층 모델에서 응력 그림자효과 고려 유무에 따른 분석을 수행하였다. 또한 지력학적 물성이 다른 두 셰일층에서 수압파쇄 모델링을 수행하여 영률과 포아송비에 따른 응력그림자효과를 분석하였다. 선행 파쇄단계의 균열로 인한 응력변화는 최대/최소 주응력을 역전시켜 T-방향보다는 생산성이 미비한 L-방향 균열이 주로 형성되었다. 또한 Marcellus 셰일의 경우 연성 특성을 갖는 Eagle Ford 셰일에 비해 높은 취성으로 인해 균열의 폭이 더 두껍게 형성되어 균열 체적이 더욱 크게 산출되었다. Marcellus 셰일지층의 영률이 Eagle Ford 셰일에 비해 크게 낮기때문에 stage 2에서 응력그림자효과의 영향을 적게 받는 것을 확인할 수 있었다. 이처럼 응력그림자효과는 균열 간의 간격 뿐만 아니라 지력학적 물성에 따라서도 크게 달라진다. 그러므로 좀 더 정확한 균열 형태와 현실성 있는 생산성 예측하기 위해 응력그림자효과는 고려되어야 한다. During multi-stage fracturing in a low permeable shale formation, stress interference occurs between the stages which is called the “stress shadow effect(SSE)”. The effect may alter the fracture propagation direction and induce ununiform geometry. In this study, the stress shadow effect on the hydraulic fracture geometry and the well productivity were investigated by the commercial full-3D fracture model, GOHFER. In a homogeneous reservoir model, a multi-stage fracturing process was performed with or without the SSE. In addition, the fracturing was performed on two shale reservoirs with different geomechanical properties(Young’s modulus and Poisson’s ratio) to analyze the stress shadow effect. In the simulation results, the stress change caused by the fracture created in the previous stage switched the maximum/minimum horizontal stress and the lower productivity L-direction fracture was more dominating over the T-direction fracture. Since the Marcellus shale is more brittle than more dominating over the T-direction fracture. Since the Marcellus shale is more brittle than the relatively ductile Eagle Ford shale, the fracture width in the former was developed thicker, resulting in the larger fracture volume. And the Marcellus shale’s Young’s modulus is low, the stress effect is less significant than the Eagle Ford shale in the stage 2. The stress shadow effect strongly depends on not only the spacing between fractures but also the geomechanical properties. Therefore, the stress shadow effect needs to be taken into account for more accurate analysis of the fracture geometry and for more reliable prediction of the well productivity.

지형 및 건축 문화유산 모형 활용 Visual-SLAM 기반 증강현실 시스템

유은지(Eunji Yoo),유정민(Jeong-Min Yu) 한국컴퓨터정보학회 2020 한국컴퓨터정보학회 학술발표논문집 Vol.28 No.2

지상주행과 공중비행이 가능한 Drone 설계 및 구현을 통한 졸업기준 인증 과정에서 공학교육 실천에 관한 연구

장우진 ( Woo-jin Jang ),유정민 ( Jeong-min Yoo ),장은영 ( Eun-young Chang ) 한국실천공학교육학회 2018 실천공학교육논문지 Vol.10 No.1

전공단위로 3학기동안 진행되는 작품 설계 및 제작 활동을 통해 졸업기준을 만족하기 위한 과정 이수와 그 과정에 만들어진 결과물인 다양한 이동환경 적용이 가능한 Drone의 구상 및 제작 과정에 대해 제안한다. Ring Propeller의 형태를 이용하여 Propeller로서의 양력 발생 역할과 테두리의 면을 통하여 지면에 접촉하는 바퀴로의 역할을 모두 가능하도록 제작한다. 또한 Servo Motor를 이용하여 명령에 따라 정확한 각도를 맞추어 모터의 구동축을 변환한다. 그리고 구상한 아이디어를 3D 프린팅으로 구현하고, 추진체 구동 회로를 설계하고 제작한다. 그 결과 추진체의 무게 증가로 공중 운항과 운항중 목적한 추진체계의 실시간 변환은 성공하지 못하였고, 그 원인으로 추력 발생을 위한 크기와 링 프로펠러의 내성 한계의 오차임을 확인하였다. 그리고 이러한 과정을 통해 공학적 접근 방법과 종합설계를 통한 창의적 사고방식 및 협동심의 경험을 인정받았고, 그 결과물을 공학 논문으로 작성하고 심사를 통해 졸업기준이 만족됨을 확인받았다. Through the design and production of works for the third semester as a major unit, It is proposed the process of satisfying the graduation standards with the design and production process of the drone which can be applied to various mobile environments. Using the shape of Ring Propeller, it is made to be able to play both the role of generating lift as a propeller and the role of a wheel that touches the ground through the surface of the rim. In addition, the Servo Motor is used to convert the drive shaft of the motor to the correct angle according to the command. Then, based on the idea, the 3D printing is implemented to confirm the result of the configuration, and the circuit for driving the propulsion is designed and manufactured. As a result, the conversion of the desired propulsion system during air navigation and operation failed due to the weight increase of the propellant. It is confirmed that the size of the thrust and the tolerance limit of the ring propeller are the errors. Through these processes, it has been recognized to have experience of creative thinking and cooperation through engineering approach and comprehensive design, and confirmed to satisfy the graduation criteria by writing an engineering paper on the result.

[P3-210610] 발달장애인들의 원예활동 선호도 조사

최유진(Eugene Choi),김미정(Mi jeong Kim),유정민(Jeong min Yoo),제의숙(Eu-sook Jea) 인간식물환경학회 2021 인간식물환경학회 학술대회 Vol.2021 No.춘계

유두 진피에 국한되어 발생한 연소성 황색육아종 1예

유정민,김성욱,장인강,조백기 대한이비인후과학회 2000 대한이비인후과학회지 두경부외과학 Vol.38 No.9

양측 이갑개(Concha)에 발생한 만성 결절성 이륜 연골피부염(Chondrodermatitis Nodularis Chronica Helicis) 1예

유정민,이현정,김진우 대한피부과학회 2002 大韓皮膚科學會誌 Vol.40 No.7

Chondrodermatitis nodularis chronica helicis is a painful erythematous, often crusted, papule most commonly found on the helix of the ear of men over the age of 40 years. It is seen less commonly in women, in whom it is usually located on the antihelix. The lesions usually occur unilaterally, although bilateral involvement has been reported. We report an unusual case of chondrodermatitis nodularis chronica helicis in an 86-year-old woman, which presented with bilateral involvement of the concha of auricles.

레이저와 불소가 인공우식병소의 항균성 및 내산성에 미치는 영향에 관한 연구

유정민,김용기 大韓小兒齒科學會 1997 大韓小兒齒科學會誌 Vol.24 No.2

The main purpose of this study was to evaluate the acid resistance and antimicrobial effect of fluoride-laser combined application. Recently extracted third molars were used. 5×3mm of the buccal and lingual specimens were exposed and incipient artifical carious lesions were formed by keeping them in the artificial cariogenic solution for 5 days. They were divided into five groups and treated with fluoride and laser according to the pre-determined regimen. The acid resistance was compared between groups by chemical quantitative analysis of the calcium and phosphorous released into the test solution after single or combined application of fluoride and laser. The antimicrobial effect of each group was analyzed by counting the number of colony forming units after microbial incubation. The results from the present study can be summarized as follow; 1. Experimental groups showed lower values in calcium and phosphorous contents as well as in CFC/㎖(colony forming units) than control group. Combined application groups showed lower values than single application groups. 2. Acid resistance and antimicrobial effect by fluoride and laser treatment were confirmed in this study. 3. Based upon the above-mentioned results of this study, it can be assumed that the use of laser-fluoride combined application may provide the child and adolescent patient population with antimicrobial effect as well as acid resistance. Further studies using various materials and experimental conditions are being encouraged.

결합조직형성 모반(Desmoplastic Nevus) 1예

유정민,이현정,서은주,김진우 대한피부과학회 2002 大韓皮膚科學會誌 Vol.40 No.7

Desmoplastic nevus, a benign melanocytic neoplasm characterized by predominantly spindle-shaped nevus cells within a fibrotic stroma without junctional activity, nesting, or pigmentation, can be confused with fibrous lesions and other melanocytic proliferations, including desmoplastic melanoma. We report a rare case of desmoplastic nevus occurring in the left helix of the ear of a 25-year-old woman, which has typical histopathologic features of desmoplastic nevus.

매복 미맹출 제 1대구치의 외과적 노출과 교정력을 이용한 견인의 치험례

유정민,김종수,김용기 大韓小兒齒科學會 1996 大韓小兒齒科學會誌 Vol.23 No.4

It is a relatively rare clinical experience to see the impacted first molar. The first permanent molar is the dey in normal occlusion. Abnormal eruption of the first permanent molars would inflict normal development of dental arches and give rise to abnormal root resorption of the adjacent teeth. Therefore, the abnormally erupted first permanent molars should be detected and treated early in order to obtain proper occlusal guidance in mixed dentition period. This report presents two cases on distally tilted and impacted mandibular first molars which were treated by surgical exposure and orthodontic traction using facial mask.

근위조갑추벽에 발생한 심재성 수장족저 사마귀 1 예

박현정,유정민,김형옥 대한피부과학회 2001 大韓皮膚科學會誌 Vol.39 No.2

Deep palmoplantar warts (myrmecia) represent lesions of the DNA virus of the papova group, human papillomavirus, serotype 1(HPV-1). They are occur not only on the palms and soles, but also on the lateral aspects and tips of the fingers and toes. Herein we report a case of deep palmoplantar wart on proximal nail fold of right index finger in a 6 year old male.