정밀 광학 부품의 복굴절 측정 방법에 관한 연구

민인기,고영배,권창오,윤경환,Min, In Ki,Ko, Young Bae,Kwon, Chang Oh,Yoon, Kyung Hwan 한국금형공학회 2012 한국금형공학회지 Vol.6 No.1

Recently, injection molding process became more popular than ever to produce large quantities of high precision products. Extensive studies have been conducted for reducing the residual stresses and birefringence in injection-molded optical products. Flow-induced and thermally-induced stresses and birefringence have been found as two main sources during injection molding process. Generally, quantitative value of birefringence can be measured with polarizing microscope using the compensator. However, it is difficult to measure low order retardation with microscope, so developing a measurement system for low order optical path difference is in need. In the present paper, a system using Photo Elastic Modulator (PEM) is demonstrated to measure low phase retardation in injection-molded products.

PBL과 전략적 텍스트를 활용한 이공계 말하기 교육 방법 모색

민인기,김경애 한국사고와표현학회 2014 사고와표현 Vol.7 No.2

This paper proposed a model of the communication educationneeded at modern requirement for engineers. At First, on this paper itwas a survey for the realistic education that students and teachersneeded. And made the draft curriculum fully reflected its result. Specially, the student majored engineering in the country, felt thenecessary for speaking education. So on this paper, made the curriculumfor them that had to change mainly speaking. Because the communication education have to the pass way forstudents to communicate with the various narratives and peoples, it issensitive at modern changes and contemporary meaning. So on thispaper was selected the themes and the subjects, not only required theassessment items for ABEEK but also the students could improved the reading skill and liberal refinement, too. The curriculum proposed on this paper is a unified course of studymainly with presentation and discussion. This paper have the meaningas a test discussion as a instructional design with PBL(Problem basedlearning) and using of the Strategic Text. 이 글에서는 이공계 의사소통교육이 지나치게 글쓰기 중심으로 이루어져 왔을뿐 아니라 말하기 교육의 필요성에 대해서는 간과해 왔다고 보고, 현대적 요구에부응하는 사고와 표현 교육 사례를 제시하고자 하였다. 사고와 표현 교육이 합리적인 방법으로 문제를 해결해 가는 민주시민의 기초를 습득하게 하는 데 교육의일차적 목적이 있고 상대를 이해하고 배려하며 자신의 생각을 명확하게 전달하는능력을 키우는 것으로 정의될 수 있다면, 글쓰기보다는 말하기가 그 본령이 되어야 할 것이다. 특히 지방 이공계 학생들의 경우 말하기 교육에 대한 필요를 더많이 느끼고 있으므로, 반드시 말하기 중심으로 재편될 필요가 있다. 먼저 현실성 있고 학생들과 교수자의 요구에 부응하는 교과목을 만들기 위해설문조사를 실시하고 이를 충분히 반영하여 교과목 초안을 잡았다. 의사소통교육은 현대의 다양한 서사물이나 다양한 사람들과 소통할 수 있는 통로를 만들어주기 위한 것이므로, 가장 시의적이고 변화에 민감해야 한다고 할 수 있다. 이 글에서는 다루는 제재를 전략적으로 선별하여 공학인증이 요구하는 평가항목을 충족하는 동시에, 문식력과 인문학적 소양도 기를 수 있는 통합교과가 되도록 수업운영계획을 세우고 발표와 토론을 위주로 하는 수업 방법을 제시하였다.

합성형 사장교의 3차원 공기역학적 특성에 대한 실험적 연구

민인기,채영석,Min, In Ki,Chae, Young Suk 한국강구조학회 2008 韓國鋼構造學會 論文集 Vol.20 No.6

The aim of this study was to analyze the aerodynamic properties of the composite cable-stayed bridge by conducting three-dimensional wind tunnel tests. Focusing on the improved section of the bridge in the two-dimensional wind tunnel tests, the bridge's aerodynamic stability was estimated based on the angles of attack and the wind angles. The aerodynamic properties of vertical galloping, torsion galloping,and torsion flutter were also estimated based on the design wind velocity, and because much of the cable-stayed bridge was constructed using FCM, it was not sufficiently stiff during the bridge's construction. Therefore,the experience progressed by stages: from the full stage to the tow stage, and until the bridge became a single tower. Since the original plane was designed to be a steel box girder, the aerodynamic properties of the steel-box-type and composite-type girder could be compared. The results of this study can be utilized as basic data regarding the aerodynamic properties of medium-length and short composite cable-stayed bridges. 본 연구의 목적은 3차원 풍동실험을 이용하여 합성형 사장교의 공기역학적 특성을 분석하는데 있다. 2차원 풍동실험에서 선정된 내풍개선 단면을 가지고 영각, 풍각에 대하여 3차원 모형의 내풍안정성을 평가한다. 설계풍속에서 수직, 비틀림 와류진동, 비틀림 플로터 등의 공기 역학적 특성을 규명하였다. 또한 사장교는 FCM으로 대부분 가설하므로 가설단계에서 강성이 부족하다. 따라서 실험은 완성계, 2개의 가설단계, 독립주탑의 단계별로 나누어 진행되었다. 원설계가 강상형교로 설계되었기 때문에 강상형교와 합성형교의 내풍특성을 비교하였다. 이 논문은 중소형 합성형 사장교의 내풍특성의 기초 자료로 활용될 수 있을 것이다

공기주입식공을 이용한 근막이완 운동이 성인의 척추 유연성에 미치는 영향

민인기,박종항,박현식,Min, In-gi,Park, Jong-hang,Park, Hyun-sik 대한정형도수물리치료학회 2020 대한정형도수물리치료학회지 Vol.26 No.2

Background: This study examined the effects of myofascial release exercise using an inflatable compression therapy ball on spinal flexibility in adults to present basic data to improve spinal flexibility. Methods: The participants were assigned randomly to two groups: the myofascial release exercise group (MRE, n=60) and the stretching exercise group (SE, n=60). The MRE group performed myofascial release exercise for the erector spine muscles using an inflatable compression therapy ball. The SE group performed stretching exercises of the erector spine muscles. Each exercise was performed in 3 sets of 10 repetition daily for one week. Results: The within-group comparison revealed a statistically significant difference between the pre-intervention and post-intervention measurements in only MRE group (p<.05). On the other hand, the between-group comparison revealed the MRE group to show statistically significant improvement in spinal flexibility (p<.05). In effect size, the MRE group was -1.82 (95% CI= -2.24~-1.39), and the SE group was -.7 (95% CI= -1.15~-.41). Conclusion: Myofascial release exercise for the erector spine muscles using an inflatable compression therapy ball was more effective in improving spinal flexibility than stretching exercises for the erector spinae muscles. However, although myofascial release exercise using inflatable compression therapy ball is more effective than stretching exercise, it is insignificant, and research is also insignificant. It is believed that more diverse studies using props will be needed in the future.

An experimental study on the effects of injection-molding typesfor the birefringence distribution in polycarbonate discs

민인기,윤경환 한국유변학회 2011 Korea-Australia rheology journal Vol.23 No.3

Even though injection molding technology has been developed for many years, it is still needed to study the effect of processing conditions on the final properties of injection-molded parts for producing precision products in optical field. The optical anisotropy, i.e., birefringence, is a significant factor which affects the function of many optical components. In the present study, we have focused on the effects of packing and compression processes on the birefringence structure remaining in the disc by examining the gap-wise distribution of birefringence and extinction angle. As a result, two extra birefringence and extinction peaks near the center in thickness direction showed the effect of packing pressure, which came from the extra flow during packing stage. Furthermore, more uniform birefringence distribution was found in injection/compression case than in conventional injection-molded case. Depending on the process condition, even the reversal flow was found from the distribution of extinction angle in injection/compression case. Finally, graphical representation technique of optical refractive indicatrix was suggested to show the difference of final birefringence structure for different process types.

Efficacy of Endoscopic Size Measurements of Signet Ring Cell Early Gastric Cancer

민인기,김주석,강선형,문희석,성재규,정현용 대한내과학회 2018 대한내과학회 추계학술대회 Vol.2018 No.1

구조물 변위계측을 위한 GNSS-IMU 센서융합모듈의 구성 및 성능시험

민인기,전인식,심재설,하동호 (사)한국연안방재학회 2022 한국연안방재학회지 Vol.9 No.4

Detecting the displacement of a structure by external forces in advance is very important in monitoring the health of the structure. In this study, a kind of sensor fusion technique that combines low-cost GNSS and IMU for structural displacement measurement was established. In addition, a data acquisition program that can secure the synchronous measurement between sensors was created. In order to evaluate the performance of this measurement module, a model experiment gauging the true value by the laser displacement meter was performed, and the results of GNSS single positioning, VRS positioning, precision single positioning (PPP), and sensor merging positioning were compared and analyzed. As a result, it was found that the PPP positioning did not capture the vibration of the structure at all regardless of the waiting time within the excitation condition of the model structure. On the other hand, GNSS single positioning was able to obtain similar results to true values and VRS positioning by pre-processing with an appropriate high-pass filter and the sensor fusion technique.

An experimental study of yellow shift in injection-molded light guide plate

민인기,이성준,이성희,김종선,윤경환 한국유변학회 2016 Korea-Australia rheology journal Vol.28 No.3

Recently, the size of light guide plate (LGP) in LCD-BLU (Backlight Unit) module is getting thinner and larger than ever. The part reached critical thickness to mold it by conventional injection molding methods due to the low flowability, melt solidification, machine limitation, and so on. Therefore, severe conditions have been applied to the part to increase the flowability such as high injection speeds and higher melt temperature. However, these approaches lead to the degradation of material and loss of optical properties. These defects are connected to the invisible part failure, so called, yellowing and color shift. In the present study a series of injection molding experiments were conducted to understand the distribution of yellowness in injection-molded LGP, and how the optical properties change under various injection molding conditions. Optical properties of yellow index (YI), CIE xy, and spectral transmittances of LGP sample were analyzed by the UV-visible spectrophotometer. Also, correlations between optical properties and process conditions were investigated from the Design of experiment (DOE). Interestingly, the value of YI, i.e., yellow shift in CIE diagram showed the maximum near the gate and decreased as the distance from the gate increased. Furthermore, as far as yellow shift concerned the data of direct transmittance are much more useful than total transmittance for evaluating color behavior. Meanwhile, analysis of variance (ANOVA) was conducted to see the effectiveness of chosen processing parameters. Mold temperature was found to be the most influential factor on the color shift and injection speed, melt temperature, packing pressure were followed.

목뼈 부위 감각운동 조절 훈련이 만성 목 통증 환자의 통증과 기능, 심리사회적 수준에 미치는 영향

민인기(In-gi Min),김선엽(Suhn-yeop Kim) 한국전문물리치료학회 2021 한국전문물리치료학회지 Vol.28 No.1

Background: It is reported that the proprioceptive sensation of patients with neck pain is reduced, and neck sensory-motor control training using visual feedback is reported to be effective. Objects: The purpose of this study is to investigate how sensorimotor control training for the cervical spine affects pain, function, and psychosocial status in patients with chronic cervical pain. Methods: The subjects consisted of 36 adults (male: 15, female: 21) who had experienced cervical spine pain for more than 6 weeks. An exercise program composed of cervical stabilization exercise (10 minutes), electrotherapy (10 minutes), manual therapy (10 minutes), and cervical sensorimotor control training (10 minutes) was implemented for both the experimental and the control groups. The cervical range of motion (CROM) and head repositioning accuracy were assessed using a CROM device. In the experimental group, the subjects wore a laser device on the head to provide visual feedback while following pictures in front of their eyes; whereas, in the control group, the subjects had the same training of following pictures without the laser device. Results: There were no statistically significant differences between the two groups in pain, dysfunction, range of motion, or psychosocial status; however, post-test results showed significant decreases after 2 weeks and 4 weeks compared to baseline (p < 0.01), and after 4 weeks compared to after 2 weeks (p < 0.01). The cervical joint position sense differed significantly between the two groups (p < 0.05). Conclusion: In this study, visual feedback enhanced proprioception in the cervical spine, resulting in improved cervical joint position sense. On the other hand, there were no significant effects on pain, dysfunction, range of motion, or psychosocial status.

정밀 광학부품의 복굴절 분석을 통한 각종 성형법의 영향에 관한 연구

민인기(I. K. Min),조성우(S. W. Cho),윤경환(K. H. Yoon) 한국소성·가공학회 2013 소성가공 : 한국소성가공학회지 Vol.22 No.1