모래의 입도분포가 모르터의 물성에 미치는 영향에 관한 연구

김경원,김문희,김유진,안흥난,허태경,현철 경성대학교 공학기술연구소 2010 공학기술연구지 Vol.16 No.-

Fineness Modulus is a term used as an index to the fineness of sand. It is well - known that the modulus distribution of sand plays an important role in achieving the desired properties of mortar. The maximum size of sand is also important parameter in mortar. These parameters affect workability, strength and unitweight of mortar. In tills study, different sand gradings were used to investigate effects of fineness moduli of sand for examination about the workability, strength and unit weight characteristics of cement mortar. Two kinds of sands with various size distribution and three kinds of fine aggregates with the similar particle size distribution (Sieve No.16~30, No.30~50, No.50~100) were used. Water-cement ratio (W/C) of mortar mix was kept constant for all the trial mixes with sand of different fineness modulus. Major findings of tills study are: (a) Fine sand with the similar size distribution reduces the workability and unit weight of cement mortar. (b) The compressive strength of mortar is not sensitive to sand grading variations. (c) The compressive strengths at the age of 28 days range from 32.1 to 54.1 MPa. (d) The sand with standard modulus distribution has better positive effects on the properties of the mortar.

무궁화 위성방송 수신용 고이득 마이크로스트립 배열안테나의 설계

김진생,신현철,이문수 慶尙大學校生産技術硏究所 1996 生産技術硏究所論文集 Vol.12 No.-

In this paper, a microstrip array antenna for receiving KOREASAT broadcasting is designed, which has left-handed circularly polarization property with the gain of 29dB at 11.84GHz. An antenna using a single feed point is chosen as an array element because of its simplicity and low feeding loss. The 2 X 2 array is a basic array element to achieve the overall 16 X 16 array antenna. All the elements of the array are fed in phase using the parallel feed method for broadside beam radiation. The actual dimension of array is about 30 X 30cm. The measured return loss and VSWR is in a good agreement with the calculations. The measured results are as follows ; SLL of -15dB below, gain of 27dB, directivity of 31.9dBi, and axial ratio of 0.74dB at 11.84GHz.

Pendulum 장치를 이용한 상악 대구치 후방이동에 관한 치험례

김문현,백병주,이지연 大韓小兒齒科學會 1993 大韓小兒齒科學會誌 Vol.20 No.2

Orthodontists have long sought methods of correcting ClassⅡ malocclusions without straining the lower arch and without the need for strict patient compliance. In the 1990s, noncompliance therapies in various forms have become more prominent than ever before. The Pendulum Appliance is a hybrid that uses a large Nance acrylic button in the palate for anchorage, along with 032˝TMA springs that deliver a light, continuous force to the upper first molars without affecting the palatal button. Thus, the appliance produces a broad, swinging arc-or pendulum- of force from the midine of the palate to the upper molars. Since the Pendulum Appliance drives the upper molars distally (with slight lingual tipping) quite rapidly, there is a tendency for the anterior bite to open. This open bite generally corrects itself in brachyfacial types, especially those with tongue-thrust habits. I still recommend treating vertical growth patterns conservatively with extraction, directional headgears, and transpalatal bars. Patient tolerance of the Pendulum Appliance has been excellent; most adapt to the appliance within a week, Initial clinical findings have been encouraging. It is not unusual to see as much as 5mm of distal molar movement in three to four months.

학생들이 사용한 엔진 구동형 Ni-Ti file systems의 근관 성형 효율 비교

강문성,김현철,허복,박정길 大韓齒科保存學會 2006 Restorative Dentistry & Endodontics Vol.31 No.1

본 연구의 목적은 학생들이 사용한 세 가지 Ni-Ti 파일의 성형효율을 비교하고, 각 파일의 사용 경험 유무에 따른 차이를 비교하여 치과대학생을 위한 교육에 적합한 종류를 선택하는데 도움을 얻고자하는 것이다. Ni-Ti 파일 사용 경험이 없는 학생 50명과 Ni-Ti 파일을 사용한 근관치료 경력이 2년 이상인 경험자 10명이 세 종류의 Ni-Ti file - ProFile^(®) (PF), HeroShaper^(®) (HS), K3™ (K3) -을 사용하여 180개의 근관 모형을 성형하였다. 근관성형 시간 및 기구 변형, 근관 이형성을 조사하고 성형 전후 상을 중첩하여 근관 삭제폭, 근관변위량과 중심변위율을 1, 3, 5 ㎜에서 분석하였다. 1. 근관 성형시간은 HS군이 가장 빨랐으며, 총 삭제량은 모든 지점에서 K3군이 다른 군보다 컸다 (P<0.05). 2. 세 군 모두 1, 3 ㎜에서 외측 변이를 보였고, 1 ㎜ 지점에서 PF군이 가장 안정적이었다 (P< 0.05). 3. 중심변위율은 1, 3 ㎜에서 HS, PF군이 K3군보다 작았다. 5 ㎜ 지점에서 PF군이 가장 작았고, PF군 3 ㎜에서 학생은 경험자보다 유의하게 작았다 (P < 0.05). The purpose of this study was to compare the shaping ability of three Ni-Ti file systems used by dental students or the experts and consequently to aid in choosing a proper systems for educational courses of dental students and beginners. Fifty students and ten dentists who have clinical experience over two years prepared 180 simulated root canals in resin blocks with three Ni-Ti systems: ProFile^(®) (PF), HeroShaper^(®) (HS), K3™ (K3). After preparation, the Ni-Ti files were evaluated for distortion and canal preparation time was recorded. The images of pre- and post-instrumented canals were scanned and superimposed. Amounts of increased canal widths,deviation, and centering ratio were calculated at apical 1, 3 and 5 ㎜ levels and statistical analysis was performed. The results were as follows: 1. HS showed the shortest preparation time and instrumented canal width in K3 was significantly larger than other groups (P< 0.05). 2. At 1 and 3 ㎜ levels, all groups had outward deviation. In student group, at the 1 ㎜ level, PF had the least deviation (P< 0.05). 3. In the centering ratio, the PF had the best centering ability compared to the others at 5 ㎜ level. At 1 and 3 ㎜ level, HS and PF had better abilities than K3. Student group had better ratio than the expert at 3 ㎜ level with PF (P<0.05). Based on the results, it is surmised that the ProFile^(®) is the safest and most ideal instrument for students and beginners.〔J Kor Acad Cons Dent 31(1):1-10, 2006〕

Papillon-Lefevre Syndrom의 임상 및 미생물학적 검사와 치료

송요한,김문현,김형섭,김재곤,백병주 大韓小兒齒科學會 1998 大韓小兒齒科學會誌 Vol.25 No.2

The Papillon-Lefevre Syndrome(PLS), a disease with autosomal recessive inheritance, is characterized by diffuse hyperkeratosis of the palms and soles, mostly prepubertal periodontitis and premature loss of primary and permanent dentition. The etiology of the destruction of periodontal tissues has not been completely clarified. In recent years, two main factors are suggested to be responsible for tooth loss : firstly, the presence of gram negative microorganisms in the periodontal pockets of the patients. The other factor suggested is cellular deficiency in chemotaxic and phagocytic function of neutrophylic granulocytes. Resent data suggestes that mechanical debridement in conjunction with antibiotic therapy may be successful in periodontal management of Papillon-Lefevre Syndrome, particularly if administered early. In this study, a Papillon-lefevre syndrome patient was studied clinically, radiologically, histopathologically and microbiologically. 5 years female patient with gingival swelling and destruction of periodontal structure on the whole dentition were examined and palmar and plantar hyperkeratosis were can be seen. On microbiological analysis, Actinobacillus actino-mycetemcomitans was performed. Concurrently, the children recieved extraction of maxillary anterior teeth and construction of removable prosthetis. The combination of professional oral hygiene care and antibiotic therapy improved the dermatologic and peridontal condition.

소아에서 발생한 비치성 양성종양에 관한 임상적 연구

백병주,김문현,김재곤,허선,김영신 大韓小兒齒科學會 1998 大韓小兒齒科學會誌 Vol.25 No.2

Non-odontogenic tumors can be classified as malignant or benign. Most oral tumors in children are benign. In the Belfact series only 7.5 percent of soft tissue tumors were malignant and Bhaskar(1963) found only 9 percent of 293 oral tumors of all kinds to be malignant. Benign tumors may be classified as epithelial and mesenchymal. The most common tumor of surface epithelium is the squamous papilloma. These are easily recgnized clinically as cauliflower-like lesions. Fibrous lesions are very common in children's mouths. Many of these are not true neoplasms but are related to fibrous hyperplasia. Another common oral tumor in children is angiomatous tumor. Hemangioma occurred more frequently than lymphangioma. Cy stic hygroma, a cystic subtype of lymphangioma, is a developmental tumor of lymphatic origin. It is a considered to be a relatively rare lesion. about 50 precent of cystic hygroma are present at birth, and most of the remaining 50 percent appear in the early years of life during the period of active lymphatic growth. The preferred treatment for these lesions, except for hemangioma, is complete surgical excision. With proper surgical techniques, recurrence is not expected.

Thermal cycling 과 시효처리가 Glass-Ionomer수복재의 인장강도에 미치는 영향

이승익,백병주,김재곤,이승영,김문현 大韓小兒齒科學會 1999 大韓小兒齒科學會誌 Vol.26 No.4

본 연구에서는 구강환경과 유사한 액상의 조건하에서의 온도변화가 광중합형 글래스아이오노머계 수복재의 인장강도에 미치는 영향을 평가하기 위해 대조군으로 2종의 재래형 glass ionomer를 선택하고 실험군으로 2종의 광중합형의 resin-modified glass ionomer와 2종의 polyacid-modified resin composite을 선택한 다음 수중에서의 thermal cycling과 시효처리를 행하였으며, 다음과 같은 결론을 얻었다. 1. 글래스아이오노머 수복재의 인장강도를 측정한 결과, polyacid-modified resin composite, resin-modified glass ionomer 그리고 재래형 glass ionomer의 순으로 나타났다. 2. 인장강도는 30일간의 시효처리로 증가되는 경향을 보였다. 3. 재래형 glass ionomer 수복재의 인장강도는 thermal cycling 처리로 증가되는 경향을 보였으며, 37℃의 증류수 중에 1시간 침적한 군과 10,000회의 thermal cycling을 비교한 결과 유의한 차이로서 강도의 증가를 나타냈다(P<0.01). 4. thermal cycling 군의 인장강도는 DR군이 45.4MPa로 최대치를, FL군이 13.4MPa로 최소치를 나타냈으며, 각 군간의 통계적 유의성을 검증한 결과 polyacid-modified resin composite의 인장강도가 나머지 군과 유의한 차이를 보였다(p<0.05). 5. 특성강도는 DR군이 48.6MPa로 가장 높은 강도치를 보였으나, Weibull 계수는 CG군이 8.9로 가장 높은 값을 보여 시험재료 중에서 가장 작은 강도의 분산을 나타냈다. This study was performed to evaluate the effect of aging and thermal cycling on the tensile strength of six commercially available glass-ionomer materials: two chemically set glass-ionomer materials(Fuji Ⅱ, fuji Ⅸ), two resin-modified glass-ionomer materials(Fuji Ⅱ LC, Vitremer), and two polyacid-modified composite resins(Compoglass, Dyract). Rectangular tension test specimens were fabricated in a teflon mold giving 5mm in gauge length and 2mm in thickness. All samples were divided into 3 groups. Group 1 was immersed in a 37℃ distilled water for 1 hour. Group 2 was immersed in a 37℃ distilled water for 30 days. Group 3 was subjected to 10,000 thermal cycles between 5℃ and 55℃, and the immersion time in each bath was 15 seconds per cycle. Tensile testing was carried out at a cross-head speed of 0.5mm/min and fracture surfaces were examined with scanning electron microscope. The results obtained were summarized as follows; 1. The polyacid-modified composite resins were stronger than the resin-modified glass-ionomer materials, which were much stronger than the conventional glass-ionomer materials. 2. Tensile strengths were slightly increased after aging treatments for 30days. 3. Tensile strengths of conventional glass ionomers were significantly increased after thermal cycling treatment(p<0.01). 4. The highest tensile strength value of 45.4MPa was observed in the Dyract group and the lowest value of 13.3MPa was observed in the Fuji Ⅱ LC group after the thermal cycling test, and the strengths of polyacid-modified composite groups were significantly higher than those of other groups. 5. The highest characteristic strength value of 48.6MPa was obtained in the Dyract group, however the highest Weibull modulus value of 8.9MPa was obtained in the Compoglass group after thermal cycling test.

'유아교육론'강좌의 성격 탐구

윤기영,표경남,류문숙,김현식 서원대학교 교육대학원 2003 교육논총 Vol.7 No.-

The purpose of this study is to provide desirable directions for early childhood teacher education. To serve this purpose, the character on 'early childhood education theories' lectures are studied and examine the actual conditions of the 'subject education theories' lectures in university or college early childhood education Dept. And analysis the theories related subject matter. The 'early childhood education theories' lecture was characterized are as followers ; First, 'early childhood education theories' lecture means whole child education as not subject matter education. Second, 'early childhood education theories' lecture means school level education as primary(elementary) school level education. Third, 'early childhood education theories' lecture means generate subject education as like integrated curriculum, not like seperate subject education curriculum.

Vertical Distribution of Hairtail catch by vertical longline

Mun-Kwan Kim,Su-Hyeon Park,Tae-Cheol Oh,Hyeong-Cheol Kang,Yong-Seok Park,Young-il An,Suk-Jong Kim 한국수산과학회 양식분과 2016 한국수산과학회 양식분과 학술대회 Vol.2016 No.10

Expression of Yolk Processing Enzyme Genes in Fertilized Eggs from Artificially Matured Female Eel, Anguilla japonica

Hyeon Ji Oh,Jung-Hyun Kim,Seong Hee Mun,Jin Hui Kim,Dae-Jung Kim,Joon Yeong Kwon 한국발생생물학회 2018 발생과 생식 Vol.22 No.3

Large quantity of eggs fail to be fertilized and many of fertilized eggs are unable to hatch in the eel, Anguilla japonica. Larvae of eel absorb egg yolk up to 8 days after hatching but the majority of hatched larvae die before they reach the stage of first feeding in this species. Genes of key enzymes for yolk processing (cathepsin B, D, L and lipoprotein lipase - abbreviated as ctsb, ctsd, ctsl and lpl, respectively) could be associated with egg quality. In this study, we investigated differences in the expression of these genes between floating eggs and sinking eggs, and also the relationship between the gene expressions of the enzymes and fertilization rates in the fertilized eggs obtained from artificially matured female eels. Expressions of yolk processing enzyme genes did not show significant difference between floating and sinking egg groups. Expression of ctsb decreased when fertilization rate was high. Expression of ctsd, ctsl and lpl, however, did not show any significant differences. These results suggest that ctsb expression could be an indicator of egg quality, and that some proteins prone to be digested by ctsb could be very important in the process of fertilization and normal cleavage in this species. Further study should identify these critical proteins to improve our understanding on the quality of fish eggs.