반복사인격자에서 동시에 생기는 두 가지 무아레 무늬를 이용한 회전변위의 가시적 측정

정연홍,오정효,조재흥,Jeong, Youn-Hong,Oh, Jeong-Hyo,Jo, Jae-Heung 한국광학회 2008 한국광학회지 Vol.19 No.4

We present the precise visual measurement method of rotational displacements using two different moire fringes simultaneously generated by repeated sinusoidal gratings. We investigate the variation of moire fringes depending on rotational displacements through computer simulation and experiment using a rotator in detail. The moire fringes are composed of the wide linear fringe part with a long period and the narrow linear fringe part with a short period. These parts are superior to the angle detection of more than 12 degrees and less than 12 degree, respectively. Additionally, the method can be visually used in the determination of the rotational direction by observing the moire fringe's direction. 컴퓨터 전산모의와 회전자를 이용한 실험을 통하여 회전변위에 따른 반복사인격자 한 쌍이 만드는 무아레 무늬의 변화를 세밀하게 조사하여 반복사인격자가 겹쳐서 동시에 생기는 두 가지의 서로 다른 무아레 무늬를 사용하는 작은 회전변위를 측정하는 가시적 방법을 보여준다. 이 무아레 무늬는12도 이상의 큰 각도 측정에 유용한 장주기의 넓고 긴 직선무늬와 12도 이하의 작은 각도 측정에 유리한 좁고 짧은 복잡한 직선무늬로 이루어져 있다. 그리고 무아레 무늬의 회전방향에 따라 회전변위의 회전방향도 동시에 가시적으로 판별할 수 있다.

리모델링한 아파트 단위주거의 빛환경 요소 실태와 조도평가

정연홍(Jeong Youn-Hong),최윤정(Choi Yoon-Jung) 대한건축학회 2008 대한건축학회논문집 Vol.24 No.8

The purposes of this study are to evaluate of the illumination and to find out the present condition of lighting elements of each space in recently remodeled apartment units. Field survey consisted of interview, observation and measurement have been conducted for 20 occupied apartment units after remodeling. As results, the present ratio of the balcony integration into children room is 40.0%. The ratios of artificial lighting fixture replacement each space are 47.3~100.0%. Most type of replaced lightings are the same position and the more brighter than the one before remodeling. The down light or assistant ceiling light which were additionally installed were not usually used in most houses. To sum up the result of artificial illumination measurement, in all the space of most houses shows that the artificial lighting illumination exceeds the maximum level of the general illumination standard for relaxation. As a result of illumination measurement on working area, as for most of areas, the illumination does not meet the standard. As for the uniformity ratio of daylight illumination, it appears that 30.0% do not meet the standard only in the living room. As for the uniformity ratio of artificial illumination, it appears that 65.0% do not meet the standard in the living room; 20.0% in the corridor; 35.0% in the kitchen; 14.3% in the study room. The results of t-test on difference of illumination by balcony integration are as follows. There is a significant differences in daylight illumination of the children rooms integrated with balcony. Also, there are significant difference of the uniformity ratio of living room's daylight illumination and that of living room's artificial illumination. The results of t-test difference on artificial illumination by lighting fixture replacement are as follows. There are significant differences in artificial illumination in the living room, the kitchen, the master room, the children room and the bathroom by lighting fixture replacement. Also, there is a significant difference in the uniformity ratio of kitchen's artificial illumination installed by lighting fixture replacement.

각막굴절력에 따른 누액층 파괴시간 분포와 연관성

정연홍(Jeong, Youn-Hong) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.6

본 연구에서는 각막굴절력에 따른 누액층 파괴시간(TBUT)의 연관성을 분석하여 콘택트렌즈의 선택 및 착 용을 위한 참고자료로 활용하고자 한다. 각막손상 및 안질환이 없는 만 21세부터 27세 이하(평균 22.87±1.48세) 대학 생들의 각막곡률반경을 각막곡률계로 측정하였다. 각막굴절력은 곡률반경을 이용하여 계산하였고 TBUT는 각막곡률 계의 마이어(mire) 상이 처음으로 왜곡되는 시간으로 측정하였다. 각막굴절력과 TBUT의 관계에서 우안의 경우, ‘y=37.921-0.610x'의 관계를 가지며 각막굴절력이 클수록 누액층이 파괴되는 시간이 단축되는 음의 연관성을 나타냈 다(r=-0.462, p=0.010). 좌안은 ‘y=41.894-0.695x'의 관계로서 음의 연관성(r=-0.509, p=0.004)으로 측정되어 좌·우안 모 두 각막근시도가 높으면 TBUT는 짧아지는 음의 상관관계가 있는 것으로 분석되었다. 이 결과는 피검자의 각막곡률 반경 측정으로 콘택트렌즈 착용여부를 결정하는데 필요한 TBUT의 기본적인 예측이 가능하다. In this study, the relation between the corneal refractive power and the tear break-up time(TBUT) was analyzed. The results can be effectively used in eye clinics and served as the reference on wearing the contact lenses. We had measured the radius of the corneal of university students who are in the range of 21 to 27 year-old and who don't have eye disease. The corneal refractive power was calculated by using the radius of the corneal. And TBUT is the time when the mire image is distorted first time. The relation between the corneal refractive power and TBUT in right eye was a linear as ‘y=37.921-0.610x', in which the larger the refractive power of the cornea is, the shorter TBUT is(negative relationship; r=-0.462, p=0.010). The relation in left eye was also a negatively linear as ‘y=41.894-0.695x'(r=-0.509, p=0.004). Consequently, in both eyes the corneal refractive power and TBUT have a negative correlation when myopia is a high. It is possible to predict TBUT, which is necessary in deciding on wear of contact lenses, by measuring the corneal radius of subjects.

측정방식에 따른 자동굴절검사의 정확도 비교

정연홍(Youn Hong Jeong) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.8

본 연구는 타각적 굴절검사에 의한 굴절이상도를 분석하여 현재 임상에서 사용되고 있는 개방형 자동굴절력계와 내부형 자동굴절력계의 성능을 평가하고자 하였다. 시력교정 및 안질환이 없는 만 18세 이상~20세 이하(평균 19.84±0.54세) 초기성인을 대상으로 포롭터를 활용한 자각적 굴절검사와 개방형 자동굴절력계 그리고 내부형 자동굴절력계의 순서로 굴절이상을 검사하였다. 자각적 굴절검사와 개방형 자동굴절검사의 Power vector 성분 SE, J0, J45의 상관관계는 r=0.92(p=0.00), r=0.14(p=0.43), r=0.12(p=0.47)이고 내부형 자동굴절검사는 r=0.98(p=0.00), r=0.21(p=0.22), r=0.08(p=0.65)으로 SE 성분은 통계적으로 매우 유의한 양적 상관성을 나타냈다. 그리고 SE, J0, J45 성분에 대한 차이의 평균은 –0.13±0.53D(p=0.17), +0.33±0.68D(p=0.01), +0.13±0.68D(p=0.26)로 J0 성분만 통계적으로 유의한 차이를 보였고 내부형 자동굴절검사와의 SE, J0, J45 차이값은 –0.30±0.42D(p=0.00), +0.30±0.71D(p=0.02), -0.02±0.63D(p=0.88)로 SE, J0 성분에서 유의한 차이가 있었다. 정확도계수와 신뢰구간은 자각적 굴절검사와 개방형 자동굴절검사에서 SE, J0, J45 성분이 1.04(+0.91~-1.17D), 1.33(+1.66~-1.00D), 1.34(+1.46~-1.20D)이고 내부형 자동굴절검사와는 0.83(+0.52~-1.12D), 1.40(+1.69~-1.09D), 1.24(+1.21~-1.25D)로 분석되었다. 시력검사에 활용되는 개방형 · 내부형 자동굴절력계에 의한 측정결과는 자각적 굴절검사의 굴절이상도를 처방하는데 예비시력 검사기기로 가능하다. In this study, the performance between subjective refraction and open-field/closed view autorefraction was estimated. We measured the refractive error of early adults aged 18 to 20 years who did not have eye disease. The differences between measurements obtained by subjective refraction and open-field autorefraction for SE, J0, and J45 were -0.13±0.53D (p=0.17), +0.33±0.68D (p=0.01), and +0.13±0.68D (p=0.26), respectively, with only J0 differing significantly. The differences between the measurements of subjective refraction and closed-view autorefraction for SE, J0, and J45 were -0.30±0.42D (p=0.00), +0.30±0.71D (p=0.02), and -0.02±0.63D (p=0.88), respectively, with only SE and J0 differing significantly. The coefficient of accuracy for SE, J0, and J45 components of open-field and closed-view autorefraction were 1.04, 1.33, and 1.34 and 0.83, 1.40, and 1.24, respectively. It is possible to predict the refractive error, which is necessary when deciding on subjective refraction, by measuring the objective refraction of open-field/closed view autorefractors.

고분자 박막인 PI - SOT의 전기광학계수 γ₃₃의 열적ㆍ시간적 안정성

정연홍(Youn Hong Jeong),조재흥(Jae Heung Jo),장수(Soo Chang),김태동(Tae Dong Kim),이광섭(Kwang-Sup Lee) 한국광학회 1999 한국광학회지 Vol.10 No.3

Mitsunobu 반응을 이용하여 전기광학계수 γ₃₃가 크고 열적ㆍ시간적으로 안정적인 폴리이미드(polyimide)계 고분자 용액인 PI-SOT(폴리이미드계 4-[N,N-bis(hydroxyethyl)amino-4´-(β-cyano-β-methylsulfonyl)vinyl]azobenzene) 고분자를 합성하였다. C. C. Teng의 단순반사법을 이용하여 코로나 폴링으로 극성 배향시킨 PI-SOT 박막의 전기광학계수 γ₃₃의 열안정성 및 시간안정성을 파장 632.8 ㎚와 852 ㎚에서 측정하였다. 그 결과 상온에서 전기광학계수 γ₃₃은 파장 632.8 ㎚서 25.12 pm/V 이고, 852 ㎚는 5.40 pm/V였다. 이 값들은 상온에서 60일 이상 장기간 안정적으로 유지되었으며, 100℃의 고온에서도 10시간내에서 6% 이내로 안정된 값을 유지하였다. We synthesized the nonlinear optical (NLO) PI-SOT(polyimide system, 4-[N,N-bis(hydroxyethyl)amino-4,-(β-cyano-β-methylsulfonyl)vinyl]azobenzene) polymer with high electro-optic coefficients as well as good thermal and temporal stabilities of the elector-optic coefficient γ₃₃by the simple Mitsunobu reaction. By using the simple reflection method of C. C. Teng, we measured the thermal and temporal stabilities of the electro-optic coefficient γ₃₃of corona-poled PI-SOT polymer at the wavelength of 632.8 ㎚ and 852 ㎚, respectively. At the temperature of 20℃, the electro-optic coefficient γ₃₃of corona-poled PI-SOT polymer were 25.12 pm/V at the wavelength of 632.8 ㎚ and 5.40 pm/V at the wavelength of 852 ㎚. These values were highly stabilized for more than 60 days at 20℃ and stabilzed within 6% for more than 10 hours at 100℃.

아파트의 겨울철 실내온열환경 실태와 생활요인 분석

최윤정,정연홍,Choi, Yoon-Jung,Jeong, Youn-Hong 한국주거학회 2008 한국주거학회 논문집 Vol.19 No.4

The purposes of this study were to determine the actual state of the indoor thermal environment in apartment units and to analyze the relationship between the living factors and indoor thermal elements. The field surveys consisted of measurements of physical elements and observations of living factors. In addition, the residents of 20 apartment units were interviewed to survey their subjective response. Field surveys were carried out from January to March 2007. Measuring elements were air temperature, globe temperature, and relative humidity. The results showed that the average of indoor temperature for the houses was $21.2{\sim}27.2^{\circ}C$, while 4 houses exceeded the comfort zone. The average of globe temperature for the houses was $21.3{\sim}27.5^{\circ}C$, while 6 houses exceeded the comfort zone. The mean relative humidity was $19.5{\sim}58.8%$, which is a relatively dry condition. The residents' average clothing value was $0.39{\sim}0.89$ clo(average 0.68 clo). The average thermal sensation vote on each room was $4.2{\sim}4.8$, which is 'neutral' to 'slightly warm'. Living factors had significant effect on indoor temperature in regression analysis were ventilation time(outdoor air exchange), opening time of door through balcony, and gas cooker use time.

학교교실의 냉방시 실내열.공기환경 실태

최윤정,정연홍,이선아,김혜경,황진아,Choi, Yoon-Jung,Jeong, Youn-Hong,Lee, Seon-A,Kim, Hye-Kyeong,Hwang, Jin-A 한국주거학회 2007 한국주거학회 논문집 Vol.18 No.4

The purpose of this study were to make clear the present condition of indoor thermal and air environment by cooling in school classrooms and to analyze the relation of the living conditions with indoor environment. The measurements on physical elements and observations on living conditions were carried out in 6 classrooms of 3 middle or high schools. Measuring elements were indoor temperature, relative humidity, PM10 and $CO_2$ concentration. As results, the averages of indoor temperature each classrooms were $24.9{\sim}26.6^{\circ}C$. Most of classrooms were lower than the Maintenance standard $(26{\sim}28^{\circ}C)$ of School Health Law. The means of relative humidity were $51.3{\sim}72%$, all classrooms were ranged within the standard $(30{\sim}80%)$. The means of PM10 concentration were $3.5{\sim}23.1{\mu}g/m^3$, all classrooms were kept within the standard $(100{\mu}g/m^3)$. The means of $CO_2$ concentration were $1218.7{\sim}4705.4ppm$, all classrooms were exceed the standard (1,000ppm). The results of analysis on relations of living conditions with the physical elements are as follow; the air conditioner set of temperature, windows and doors opening elapsed time, the number of students in classrooms and activities of students had certain effect on indoor environment.

아파트 단위주거의 리모델링 요소와 현황 - 인테리어디자인업체 실무자와 거주자 심층면접을 통하여 -

최윤정,심현숙,정연홍,Choi, Yoon-Jung,Shim, Hyun-Suk,Jeong, Youn-Hong 한국주거학회 2007 한국주거학회 논문집 Vol.18 No.6

The purpose of this study was to grasp major elements and actual condition of apartment unit remodeling by in-depth interviews on residents and specialists. The interviews had been conducted to interior designers who have a wide experience of apartment remodeling and residents who live in recently remodeled apartment unit. In-depth interview is a kind of qualitative method in which attention to reply of responses with open-access between interviewer and respondents. According to the results, remodeling elements were generally changing of lighting fixtures and finishing materials in the all spaces, integration of balcony into children's room, installation of furniture in kitchen and entrance, changing storage furnitures and equipments in bathroom. Artificial lighting method were selected generally whole lighting. Finishing materials were used ordinary (non environmentally-friendly) wallpaper and adhesion and tempered floor. There were unsatisfied factors after remodeling, these were dissatisfaction of design, construction defects, and stink of reflecting 'sick house'. Also they responded that they should be considering to use environmentally-friendly material at next remodeling.

한국형 그린 캠퍼스 모델개발 및 추진전략 제안연구

최윤정(Choi, Yoon-Jung),정연홍(Jeong, Youn-Hong) 한국주거환경학회 2018 주거환경(한국주거환경학회논문집) Vol.16 No.2

Green campus implementation in Korea is still in its beginning stage and hasn"t have its standardized guideline holding the holistic concept of green campus, so a systematic approach is needed. This study was conducted during the last four years. First, field surveys of 4 abroad advanced cases of green campuses were completed. Secondly, in order to understand the situation of Korean green campuses, a literature review on the related system and a questionnaire survey on universities of the whole country as a population were completed. This paper suggested a Korean-style model and strategies that are supplemented through a focus group interview with experts on the draft. The draft has developed based on preceeding results by drawing of benchmarking elements, classifying of promotion elements, and putting together elements from abroad advanced cases and domestic evaluation items. This paper established goals for green campus in three aspects, i.e. physical, sociocultural, and human. To propose a green campus model, this study established conceptualized four large categories including the university administration, the research and education, the engagement, and the sustainable physical campus. A Korean-style model was suggested via a diagram that is comprised of the sustainable physical campus supported by the other three sociocultural categories. To organize a strategies to be useful manual for hands-on staff of universities in Korea, the elements corresponding to each category were listed based on terms such as practicable or prerequisite in the short-run, mid-term implementation, and long-term preparation.

스테인리스강을 사용한 분말 적층 용융 방식의 금속 3차원 프린터에서 제작된 물체의 최소 선폭 측정

손봉국(BongKuk Son),정연홍(Youn Hong Jeong),조재흥(Jae Heung Jo) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.10

금속 3D 프린팅 기술은 레이저 빔의 초점에 금속분말을 주입하는 방식에 따라 대표적으로 PBF(Powder Bed Fusion) 방식과 DED(Direct Energy Deposition)방식으로 나뉜다. DED 방식은 금속 분말 도포와 동시에 레이저를 조사하여 3차원 구조물을 제작하는 금속 3D 프린팅 기술이고, PBF 방식은 일정 높이로 3차원 그래픽을 슬라이싱 한 후 한 층씩 금속 분말을 적층하여 레이저를 이용해 3차원 구조물을 제조하는 방식이다. DED 방식을 사용하면 레이저 클래딩, 금속 용접 등에는 강점을 가지지만 3D 형상을 제작할 경우 밀도가 낮아지는 문제점이 발생한다. DED 방식에서의 구조체 밀도 문제를 해결하기 위해 PBF 방식을 도입하면 상대적으로 밀도가 높은 3차원 구조물을 제작하는데 용이하다. 본 논문에서는 갈바노 스캐너와 광섬유로 전송되는 Nd:YAG 레이저 빔을 이용한 약 30 ㎛ 크기의 스테인리스 강 분말을 이용하는 PBF 방식의 3차원 프린터를 제작하고, 이를 이용하여 얇은 금속 구조물을 제작하였다. 또한 레이저의 조사 횟수, 출력, 초점 크기, 스캐닝 속도에 따른 선폭의 최적조건을 찾았으며, 그 결과 최적 조건은 레이저 조사 횟수 2회, 출력 30 W, 초점 크기 28.7 ㎛, 스캐닝 속도 200 mm/s에서 최소 선폭은 약 85.3 ㎛로 측정되었다. Metal three-dimensional (3D) printing technologies are mainly classified as powder bed fusion (PBF) and direct energy deposition (DED) methods according to the method of application of a laser beam to metallic powder. The DED method can be used to fabricate fine and hard 3D metallic structures by applying a strong laser beam to a thin layer of metallic powder. The PBF method involves slicing 3D graphics to be a certain height, laminating metal powders, and making a 3D structure using a laser. While the DED method has advantages such as laser cladding and metallic welding, it causes problems with low density when 3D shapes are created. The PBF method was introduced to address the structural density issues in the DED method and makes it easier to produce relatively dense 3D structures. In this paper, thin lines were produced by using PBF 3D printers with stainless-steel powder of roughly 30 ㎛ in diameter with a galvano scanner and fiber-transferred Nd:YAG laser beam. Experiments were carried out to find the optimal conditions for the width of a line depending on the processing times, laser power, spot size, and scan speed. The optimal conditions were two scanning processes in one line structure with a laser power of 30 W, spot size of 28.7 ㎛, and scan speed of 200 mm/s. With these conditions, a minimum width of about 85.3 ㎛ was obtained.