• 구강회복응용과학지
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• 제23권3호
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• pp.239-248
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• 2007

The accuracy and dimensional stability of rubber impression materials are very important for the fitness of the final restoration. The purpose of this investigation was to evaluate the effects of the storage time and pouring frequency of the additional silicone materials on dimensional stability. Total 30 impressions were made of tooth prepared single crown. The dies had 1 buccolingual, 1 mesiodistal and 1 occlusogingival lines. Two additional silicone materials(examixfine, aquasil) were included. 15 specimens were made of each impression material and poured by type IV stone over times(1hour, 24hours, 72hours) after mixing. 5 impressions poured after 1 hour were used for second pouring after 24hours and third pouring after 72hours. The same examiner measured each specimen 3 times after lazer scanning. All statistical tests were performed with the level of significance set at 0.05. The results indicated that significant difference at any measuring point of stone dies except the buccolingual and mesiodistal lines of the specimen made at 1hour after mixing with examixfine when measurements at 1hour, 24hours and 72hours were campared. There were significant difference between two impression materials and at every measuring point of stone dies made at second and third pouring. The length of measuring point increased significantly as time passed by and increase of the pouring frequency. However, this results are clinically acceptable except the dies of the third pouring. Under the conditions of this study, the shrinkage rate of the additional silicone rubber impression materials significantly increased as time passed by and increase of the pouring frequency.

• 천문학논총
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• 제37권3호
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• pp.35-47
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• 2022

This study investigated the stone Angbu-ilgu (scaphe sundial) of the Korea Meteorological Administration (KMA) and the Seoul Museum of History (SMH). Since the first Angbu-ilgu was produced in Korea in 1434 (the year of the reign of King Sejong), Angbu-ilgu has been reproduced with various materials. The upper surface of these two stone Angbu-ilgus symbolizes the horizon. On the hemisphere concave at the center of the horizon, the South Pole, the time line, and the season line are engraved. On the horizon of both the KMA and SMH Angbu-ilgus, the schematic, typeface, and composition of the inscription completely coincide with each other. In this study, it was estimated that the appearance of the KMA Angbu-ilgu, which was damaged at some point previously at least once, was similar to that of the SMH Angbu-ilgu, and this means that it is superficially similar with Treasure No 840, the stone horizontal sundial. In the concave hemisphere of both the stone Angbu-ilgus of the KMA and SMH, there are hour lines and 24 solar-term lines (13 line), and there is an intersection point where these lines meet the horizon, respectively. It can be verified that these intersections of these two Angbu-ilgus can be calculated as having a latitude of +37°39'15". The hour lines of the two stone Angbu-ilgus show that they were made after about 1900.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.66-69
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• 2001

Previously we developed a CHO cell line (CHO-OTC1-A19) expressing the first two enzymes of urea cycle. This cell line showed higher ammonia removal activity and faster growth rate than the vector controlled CHO cells (CHO-neo-5). The purpose of this study was to develop a cell line with higher ammonia removal activity than the cell line developed previously. To accomplish this, we constructed stable CHO cell lines expressing the first three, the first four, or all five enzymes of urea cycle by the stable transfection method. We finally selected CHO-AL-19 cell line expressing the first three, the first four enzymes of the cycle with higher ammonia activity than CHO-OTC1-A19 and CHO-n대-5 cell lines: 40% and 15% higher than those of CHO-neo-5 and CHO-OTC1-A19 cell lines 72 hour after culture started, respectively. It also showed 44% and 10% higher cell viability than CHO-neo-5 and CHO- OTC1-A19 cell lines at higher cell density. In addition, CHO-AL-19 cells showed 45%-60% and about 20% lower ammonia concentration per cell than those of CHO-neo-% and CHO-OTC1-A19 cell lines, respectively. These results indicate that CHO-AL-19 could be used in the production of human therapeutic proteins with higher efficiency.

• 한국기계가공학회지
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• 제10권4호
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• pp.121-126
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• 2011

An accumulator placed on the refrigerant cycle pipe lines is a part to relax fluctuations of pressure within the pipe lines and stabilize refrigerants flowed into pipe. The accumulator has been mainly manufactured by the process of tube spinning using CNC(Computer Numerical Control) lathe. However, this process has the defects which are low productivity per hour and high cost. For that reason, tube end-forming using roll die is actively being developed, recently. The purpose of this study is to develope the tube end-forming process using roll die in order to manufacture the accumulator for the refrigeration pipe lines. First, the process design of tube end-forming was performed based on specification of product, and then was verified with FE analysis. Also, the effects of friction coefficient and revolution speed of roll die on forming load were investigated. The analytical results were applied in the final process design of tube end-forming. Finally, tube end-forming test was carried out to verify the validity of the FE analysis and the process design.

• Journal of Astronomy and Space Sciences
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• 제32권1호
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• pp.73-80
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• 2015

The Yang-gyeong-gyu-il-ui (兩景揆日儀) is a kind of elevation sundial using three wooden plates. Sang-hyeok Lee (李尙爀, 1810~?) and Byeong-cheol Nam (南秉哲, 1817~1863) gave descriptions of this sundial and explained how to use it in their Gyu-il-go (揆日考) and Ui-gi-jip-seol (儀器輯說), respectively. According to Gyu-il-go (揆日考) there are two horizontal plates and two vertical plates that have lines of season and time. Subseasonal (節候) lines are engraved between seasonal (節氣) lines, subdividing the interval into three equal lines of Cho-hu (初候, early subseason), Jung-hu (中候, mid subseason) and Mal-hu (末候, late subseason); there are 13 seasonal lines for a year, thus resulting in 37 subseasonal lines; also, there are 12 double-hour (時辰) lines for a day engraved on these plates. The only remaining artifact of Yang-gyeong-gyu-il-ui was made in 1849 (the $15^{th}$ year of Heon-jong) and is kept at the Korea University Museum. We have compared and analyzed Yang-gyeong-gyu-il-ui and similar western sundials. Also, we have reviewed the scientific aspect of this artifact and built a replica. Yang-gyeong-gyu-il-ui is a new model enhanced from the miniaturization development in the early Joseon Dynasty and can be applied to the southern part of the tropic line through a structure change.

• 대한수의학회지
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• 제35권2호
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• pp.317-326
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• 1995

The purpose of this study was to establish a method for in vitro culture of C parvum isolated in Korea by determination of suitable cell model to complete development of this parasite. The result obtained were summerized as follows: 1. To determine the most suitable cell line, six types of cell line were examined by microscopy. All cell lines were infected with C parvum and showed the highest infection score in HmLu cells. 2. The staining methods including DMSO-modified acid-fast(A-F) stain, hematoxylin-eosin(H & E) stain and immunofluorescence antibody(IFA) stain were applied to examine the infection of C parvum in cell culture. These staining methods were possible to examine the infection of C parvum in cell culture. The most sensitive one was IFA staining technique. 3. Developmental stages of C parvum in HmLu cell were observed. After the initial 8 hour incubation period, some trophozoites were observed. The meronts and gametes were appeared at 24-48 hour post inoculation(PI), and oocysts were observed firstly at 48-72 hour PI. 4. In H & E stain, the parasite appeared as basophilic within parasitophorous vacuole membrane(PVM) and lying in cytoplasm at near the nucleus of the host cells. It was able to distinguish the type I, type II meronts and gametes. 5. In DMSO-modified acid-fast stain, specific stained parasites were appeared firstly after 48 hour PI. The parasites were showed with different degrees of staining bright red color within PVM. 6. The endogenous stages of parasites in HmLu cell recovered at 48, 96, 120 and 144 hour after inoculation were reacted with rabbit immunized serum in immunofluorescence antibody and avidin-biotin complex peroxidase staining technique.

• 한국철도학회논문집
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• 제8권6호
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• pp.507-512
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• 2005

Railroad transportation system has experienced major changes due to KTX introduction. Kyungbu corridor especially Seoul to Cheonan has line capacity problem and its solution has been a primary concern to researchers and policy decision makers. This study explored pattern of train operation between Seoul and Cheonan after the introduction of KTX in 2004. Both the number of trains and available seat capacity per day have increased but maximum number of trains per specific hour has not been changed much. Demand for train shows that if concentrated in a specific time, so number of trains during the peak hour should be increased. But, it is difficult ? 새 line capacity, so increasing seat capacity per train might be an option. An increase in an avaliable sear should be considered the characteristics of each train lines.

• 대한의생명과학회지
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• 제15권2호
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• pp.153-160
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• 2009

Photodynamic therapy(PDT) is a treatment utilizing the generation of singlet oxygen and other reactive oxygen species(ROS), which selectively accumulate in target cells. The aim of present work is to investigate the photodynamic therapy mechanism of 9-HpbD-a-mediated PDT in HeLa cell lines. We studied the general reactive oxygen species(G-ROS) activation after 9-HpbD-a PDT using fluorescence stain with $H_2DCF-DA$. G-ROS activation observed after 9-HpbD-a PDT and higher activation condition was 1 hour after PDT at 0.5 ${\mu}g/ml$ 9-HpbD-a concentration. Sodium azide and reduced glutathione(the singlet oxygen quencher) could protect HeLa cells from cell death induced by 9-HpbD-a PDT. But D-mannitol(the hydroxyl radical scavenger) could not protect cell death. Singlet oxygen played a decisive role in 9-HpbD-a PDT induced HeLa cell death. Type II reaction was the main type of ROS formation at 9-HpbD-a PDT.

• 산업공학
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• 제17권3호
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• pp.375-383
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• 2004

The purpose of this study is to investigate the characteristics of vibration induced by the powered hand tools used in the automobile assembly lines, and estimate the prevalence of vibration syndrome. The acceleration levels of four major powered hand tools were measured using the ISO 5349 method along with the time of exposure to the vibration of the hand tools. Four-hour-energy-equivalent frequency-weighted accelerations ranged from $1.27m/s^2$ to $2.58m/s^2$, After exposure to vibration for 12.6 years, about 10% of the workers using impact ranches were expected to develop Raynaud's disease. For the workers using grinders, 16.6% of the workers were expected to develop Raynaud's disease. The results would be of help in developing the guidelines of local vibration control.

• 한국작물학회지
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• 제50권spc1호
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• pp.112-117
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• 2005

본 연구는 lipoxygenase 결여 품종인 진품콩2호와 lipoxygenase 가 존재하는 광안콩, 소백나물콩, 푸른콩의 교배조합 내의 각 계통의 lipoxygenase 유무를 확인하고 activity 차이를 규명함으로써 lipoxygenase 결여 나물콩 육성의 가능성을 알아보고자 수행되었다. 콩나물 재배일수별 lipoxygenase 여부, 재배일수별 lipoxygenase 활성도 등을 분석한 결과를 요약하면 다음과 같다. 1. 콩나물 발아율은 대비품종과 계통들간의 큰 차이는 없었지만 정상 발아 개체율 에서는 계통이 $63\%$로 낮았으며 $T_{50}$은 1일로 소백나물콩, 푸른콩(0.6일)보다는 느렸으나 진품콩2호, 광안콩보다는 빨랐다. 2. 콩나물 생육은 치상 후 2일부터 콩나물 전체길이, 배축길이, 배축 직경을 조사한 결과 진품콩2호와 푸른콩 교배 조합 계통의 4537계통(콩나물 전체길이 13.9cm, 배축 길이: 7.3cm, 배축 직경: 2.2mm)이 대비품종들보다 높은 신장성을 보였다. 3. 콩나물의 물성은 치상 후 96시간 후에 hardness, cutting force, masticcation을 측정한 결과 lipoxygenase 결여 계통이 대비품종들보다 높게 측정되었다. 4. 콩나물 재배 일수 별 lipoxygenase band는 자엽부에서는 종실과 같이 lipoxygenase band를 확인 할 수 없었으며 배축부에서 모든 계통과 대비품종에서 확인 할 수 있었다. 5. 콩나물 재배 일수별 lipoxygenase 활성도는 2일차에 최고로 높았으며, 3일차에 최저치로 낮아진 후 다시 증가하는 양상을 나타내었다. 6. 각 교배 조합 내에서는 진품콩2호보다 활성도가 낮은 4510, 4522, 4537계통들이 lipoxygenase 결여 콩나물로서의 육종 가능성이 높을 것으로 생각되었다.