昇降溫時 岩石에 對한 熱傳導率의 溫度依存性

姜大雨 동아대학교 공과대학 부설 한국자원개발연구소 1988 硏究報告 Vol.12 No.2

Thermal properties of rocks at elevated temperature and high pressure have been highly concerned in geothermal energy development and in many fields of engineering. These samples are measured by a needle probe method. Temperature dependences of the thermal conductivity of 21 core samples with the increase and decrease of temperature are presented in the temperature range from 30 to 460℃. The experimental temperature data to yield values of the thermal conductivity is obtained in about fifteen minutes. Temperature dependence of the thermal conductivity increases with the increase of temperature and decreases with the decrease of temperature. The range of the thermal conductivity of core samples presents from 0.5(w/m.k) to 2.4 (w/m.k) at the experimental temperature. Mudstone, pumice tuff, lapilli tuff, dacite, Sandy tuff and tuff breccia were nearly the same thermal conductivity. Fine grain tuff can be distinguished by the thermal conductivity of the increase and decrease of temperature.

154kv 대신 S/S 인출 전력구 시험발파 패턴 및 진동, 소음 계측에 의한 기존 CRACK에 미치는 영향 연구

강대우,박태원 동아대학교 건설기술연구소 1998 硏究報告 Vol.22 No.1

This area is covered in Andesite of high compression strength and located in PUSAN SEO­KU. There are many old houses around shaft site. So, we must have a cautious blasting operation. A total of 40 blasts were test at DAE-SHIN Shaft site to study the magnitude and frequency characterization of blast-induced vibration. The effect of viblating frequency on structual damage and site-specific scaling to define the empirical equations were also discussed. The results can be summarized as follows: 1. Some empirical equations were obtained. V=K{(D/W)1/3}^(-n), where the values for n and K are estimated to be -1.407 to -2.202 and 643.3489 to 7283.2104 respectively. 2. Dominant frequencies at shot distance are in the range of about 75.0 to 91.8 Hz, with some exceptions of about 50Hz, Frequencies obseverd at long distance are in the range of 10 to 20Hz. It is apparent the shift of dominant frequency down to lower levels at long distance.

Hydrogen Behavior in Ti-Added Reduced Activation Ferritic-Martensitic Steels

Kang‑Mook Ryu,Dae Geon Lee,Joonoh Moon,Chang‑Hoon Lee,Tae‑Ho Lee,Jae Sang Lee,Dong‑Woo Suh 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

Hydrogen behavior and corresponding mechanical degradation were examined in TaTi-RAFM and EUROFER97 steels. Increased Ta content with Ti addition decelerates the hydrogen diffusion but increases the solubility in the lattice. It ismainly led by the higher fraction of Ta-rich MC carbides and dislocation density in TaTi-RAFM steel. Overall activationenergy of hydrogen trapping of investigated steels is evaluated to be 25.3 ~ 25.6 kJ/mol in the tempered condition. The activationenergy increases to nearly 30 kJ/mol when the steels are re-austenitized and quenched. Higher activation energy withincreased dislocation density indicates that the dislocation provides for trap site with higher activation energy than Ta-richMC carbide. Mechanical degradation by hydrogen with respect to the yield strength, tensile strength and uniform elongationcould not be observed in all investigated steels. The presence of hydrogen only has influence on the loss of post-uniformelongation. For a given charging time, the loss of post-uniform elongation is more remarkable in TaTi-RAFM steel due tothe larger hydrogen uptake.

Flowable Resin을 이용한 접착식 보정장치의 결합강도 연구

강대근,손우성,김형일 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.4

This in vitro investigation was conducted to determine the bond strength of two resin material using universal testing machine and to verify the failure mode for each test specimen with stereoscope. Eighty human permanent maxillary and mandibular premolars were randomly divided into 2 groups (40 in each group). Teeth were mounted in stone block (2 teeth in each block) and a 3 mm diameter area of enamel of each sample were etched, rinsed, dried, and adhesives were applied according to the manufacturers' instructions. A bonded orthodontic retainer with triflex wire was bonded to buccal enamel surface. Debonding was then performed with a force using an Instron universal testing machine. The force was recorded at bond failure. The results data was collected and the mode of fracture failure recorded. The broken specimens were examined with 20× stereoscope to determine the fracture location or failure mode. Failures for each adhesive system were evaluated with ARI scores. The t-test was performed to determine any statistically significant differences among bond strength values of the two materials. And Chi-square test was used to compare the Modified adhesive remnant index (ARI) scores for the two groups. This in vitro study concluded that; 1. There was no statistical difference in mean bond strength between the flowable (Filtek Flow^(�)) and conventional (Filtek Z250^(�)) resin material (p=0.128). 2. The fracture modes of all samples were resin-wire interface failure or combination of enamel-resin and resin-wire interface failure. Bonded lingual retainer with flowable resin might have clinically acceptable bond strengths. Modes of failure site of flowable resin and conventional composite resin were similar.

Berkshire豚의 産仔數와 育成率의 反復力

姜大珍,林鍾佑,朴忠生 慶尙大學校 1976 論文集 Vol.15 No.-

國立種?場 酉州支場에서 1969年부터 1972年까지 保有 縷?에 供用한 62頭의 Berkshire의 總 225부에 대한 資料를 기초로하여 産仔數와 育成率에 대한 反復力을 推定하였다. 産仔數는 年度 季節 및 産次의 差異에 대하여 複定하였고,育成率은 年度, 戒節, 産次, 産仔數 및 仔?의 性別 差異 대하여 統計的으로 補正하였다. 産仔數의 反復力은 0.293±0.073, 그리고 育成率의 反復力은 0.089±0.066으로 推定되었다. Repreatabilities of letter size at birth adn percent pigs raised to weaning of Berkshire swine were estimated based on the data from 225 litters produced at the Sacheon Branch of the National livestock Breeding Station from 1969 to 1972. The litter size at bith was adjusted for differences in year-season of farrowing and number of farrowing of sows and the percent pigs faised to weaning was adjusted for differences in year-season of farrowing, number of farrowing, letter size at birth and sex of pigs. Repeatabilities estimated were 0.293+0.073 for litter size at birth and 0.089+0.066 for percent pigs raised to weaning at 56 days of age.

8년간(1992~1999) 산업안전보건연구원에 의뢰된 직업병 심의 사례 분석

강성규,김규상,김양호,최정근,안연순,진영우,최병순,양정선,김은아,채창호,최용휴,김대성,박정선,정호근 대한산업의학회 2000 대한직업환경의학회지 Vol.12 No.2

Objectives : Pneumoconisis and noise-induced hearing loss (NIHL) have been reported as main occupational diseases by the Special Health Examination. The Industrial Accident Compensation Insurance has reported various work-related diseases, however, these two diseases occupied almost a half of compensated cases. Therefore, it was not well known about the status of occupational diseases other than pneumoconiosis, NIHL, and cardio-cerebrovascular accident (CVA). This study was conducted to analyze claimed cases as an occupational disease, that was requested to the Korea Industrial Safety and Health Agency (KOSHA). Methods : The local office of the Korea Labor Welfare Corporation (KLWC) has asked the KOSHA for confirmation of claimed cases as an occupational disease. We analyzed 379 cases requested from KLWC, the Ministry of Labor, employers, unions and occupational health agencies from 1992 to 1999. Results : Male was 80.7 % of the requested cases. Their mean age was 42 years old and 75.5 % of them were more than 35 years old. The requested cases were increased rapidly from 25 cases in 1992 to 108 cases in 1999 and the accept rate was 50.7 %. The majority of requested cases were respiratory diseases(22.4%), cancers(18.5%), Neuropsychiatric problems(14.5%), and musculoskeletal problems(13.5%). The accept rate was high in reproductive, respiratory, musculoskeletal and digestive disorders and low in neuropsychiatric, renal and otologic problems and occupational cancers. 73.6% of them were caused by chemical agents, especially 28.5 % were by organic solvents. 67% of them were clinically confirmed at university hospitals. A half of the cases were from KyongIn area, even the request came from the whole country. Conclusions : A claim was common in workers whose age was over 35 years old and exposure history was over 10 years. The respiratory diseases and neuropsychiatric disorders were still main problems in occupational health and occupational cancers was increasing even though its accept rate was not high yet.

진동 저감을 위한 수직구 발파의 패턴 비교

강대우,안봉도 동아대학교 건설기술연구소 1998 硏究報告 Vol.22 No.1

This study aims, at applying the optimal shaft blasting patterns in the urban area, Vibrations were measured with and without vibration reduction methods at a urban site in Pusan. The results were analyzed with respect to scaled distance, frequency distribution, and blasting pattern. The conciusions are as follows: 1. The relationship formula between vibration velocity and scaled distance are found with the confidence level of 95%. without reduction methods : V_(95)=4041.3350(SD)^(-1.717) (square root) V_(95)= 2229.0863(SD)^(-1.717) (cube root) with reduction methods : V_(95)= 563.3637 (SD)^(-1.192) (square root) V_(95)=436.6020(SD)^(-1.253) (cube root) 2. The main frequency of vortical component Is found to the higher than in 100Hz in most of the measurements, while the transverse component has the main frequency lower than 60Hz, in the meanwhile, it is hardly found in the case of longitidual component. 3. Measurements were made at a bulding approximately 5m apart from the blasting site. The blasting pattern with vibration reduction methods shows much lower vibration. The reduction magnitudes are 12.7% for the squre root formula and 13.8% for the cube root when the thres hold limit value in set at 10mm/sec. Comparisions are made with the same charging weight per delay at the same distance.

두 계통 잉어의 체성분 비교

강석중,최병대,정우건 國立統營水産專門大學 附設 水産科學硏究所 1994 수산과학연구소보고 Vol.5 No.-

보통잉어와 이스라엘잉어를 같은 조건에서 사육하였을 때 두 품종 간의 체성분 변화를 조사하기 위하여 식물성 플랑크톤이 많은 동일한 조건에서 사육한 보통잉어와 이스라엘잉어의 아미노산 및 지방산 조성을 분석하였다. 근육과 내장의 일반 성분을 분석한 결과 근육 중 조지방의 함량은 보통 잉어가 높았고, 회분은 이스라엘잉어가 높았으며 내장 중의 조지방의 함량은 이스라엘 잉어가 휠씬 높았으나, 회분의 함량은 비슷하여 지방의 함량에서 차이가 있었다. 구성 아미노산의 함량 및 패턴은 비슷하였고 주된 아미노산은 aspartic acid, glutamic acid, leucine 및 Iysine이었으며 전체 함량의 약 42%를 차지하였다. 또한 필수 아미노산이 차지하는 비율은 38~43%으로 높았다. 유리 아미노산 중 주된 성분은 taurine과 histidine이었으며 이들이 맛에 영향을 줄 수 있으나 두 품종 간에는 이들 함량이 비슷하였기 때문에 맛에는 차이가 없을 것으로 사료된다. 지방산 조성은 극성 지질 중 eicosapentaenoic acid(20:5n-3) 및 docosahexaenoic acid(22:6n-3)의 함량이 높아 건강 식품으로서의 가치가 있는 것으로 나타났다. The differences of nutritive components in muscle and viscera of local and Israeli strains of common carp were examined. The crude lipid content in muscle was higher in the local carp than in the Israeli carp, but that in viscera was lower in the local carp than in the Israeli carp. There was no appreciable differences of crude protein and ash in viscera between local and Israeli carp. The distribution patterns of the total amino acid profiles for both local and Israeli carp were very similar. The principal amino acids were aspartic acid, glutamic acid, leucine and Iysine. They were 42 percent of total amino acids. Taurine and histidine were important part of free amino acids. Eicosapentaenoic acid and docosahexaenoic acid content in the polar lipids were high in both strains.

脂質 종류에 따른 나일틸라피아의 성장 효과

강석중,최병대,정우건 國立統營水産專門大學 附設 水産科學硏究所 1994 수산과학연구소보고 Vol.5 No.-

양어 사료에 피드오일을 첨가하면 사료 효율이 향상된다. 나일틸라피아가 요구하는 필수 지방산의 종류를 알아보기 위하여 대두유 및 옥수수유 등의 식물유 및 오징어 간유, 어유를 사료에 첨가하고 사육하여 다음과 같은 결과를 얻었다. n-6 계열이 풍부한 식물유를 투여한 실험구가 n-3 계열의 어유를 투여한 실험구 보다 성장이 좋았으며 그 중에서도 대두유 첨가구가 가장 양호하였다. 총 지질중의 20:3n-9의 수준은 유지의 종류에 따라 현저한 차이는 없었으나 극성 지질중의 20:3n-9의 수준은 어유 및 오징어 간유 보다는 식물유구에서 낮게 나타났다. 틸라피아 사료에 첨가하는 지질로서는 n-6계열을 많이 포함하는 것이 적당할 것으로 나타났다. Experiments were conducted to find out suitable dietary lipids in the practical feed for Nile tilapia, Oreochromis niloticus. Soybean oil, corn oil, fish oil or cuttlefish liver oil was mixed in the diet and tested. The best weight gain and feed efficiency were obtained from the fish fed soybean oil or corn oil, both rich in 18:2n-6. But the growth rate of fish fed diet with fish oil or cuttlefish liver oil were inferior. The levels of 20:3n-9 in the total lipid were not different in all tested lipids, but that in the polar lipid of the fish oil or cuttlefish liver oil were lower than that in the soybean oil or corn oil. Thus, vegetable oil such as soybean oil or corn oil, rich in 18:2n-6, were suitable as dietary lipid for Nile tilapia. Unlike other fish species, fish oil or cuttlefish liver oil showed no essential dietary value for this species.

외경 0.25 ㎜ 동맥의 단단 및 단측문합법

전대우,정재홍,강진성,한기환 大韓成形外科學會 1989 Archives of Plastic Surgery Vol.16 No.3

Microvascular surgery has rapidly developed in the last 30 years and vessels of 1.0 mm can be anastomosed easily with a patency rate over 90 percent and is widely used in clinical practice with remarkable success. To obtain more successful microvascular anastomosis in smaller vessels, the improvement in methods of microanastomosis, the development of microvascular instruments including the operating microscope along with microsutures, and anticoagulants are needed. These improvements made microvascular anastomoses of vessels that are less than 0.5mm in extemal diameter possible. Huang et al.? performed anastomoses of the vessels in rats with an external diameter of 0.2 mm using a high magnification operating microscope, specially designed microinstruments, and fine sutures, and achieved a patency rate of 76 percent in the second postoperative week. However, we tried to anastomose vessels with an external diameter of 0.25 mm with ordinary instruments and 11-0 nylon. Animal studies on 180 rats were carried out by doing end-to-end anastomoses and 180 end-to-side anastomoses. In the end-to-end and end-to-side anastomoses, each 180 rats were then divided into 3 groups each. Group A was the control group. Aspirin and persantin were given orally in group B. Ticlopidine hydrochloride was given orally in group C. The method of end-to=end anastomosis was as follows : A superficial epigastric artery as small as 0.25 mm in diameter was severed transversely and longitudinal incisions, the length of the arterial diameter, were made down opposite sides of each end. Each flared fragment of the proximal end is approximated with each distal end and sutured together by only two stitches. The method of end-to-side anastomosis was as follows. In the side of the femoral artery an elliptical hole was made the same length of the circumference of the superficial epigastric artery, then the superficial epigastric artery was incised in the same manner as the end-to-end anastomosis. The flared ends of the superficial epigastric artery were then inserted into the hole of the femoral artery and sutured by four stitches. Light microscopic and scanning electron microscopic observation was performed serially at 3 days, 2 weeks, 3 weeks after the microvascular anastomosis for studying change of vessel diameter and histopathological changes at the microvascular anastomotic sites. The results were as follows : 1. The patency rate for the end-to-end anastomoses in the third postoperative week was 25% in the control group(A), 35% in the aspirin-persantin group(B), and 40% in the ticlopidine group(C) ; in the end-to-side anastomoses, 45% in group A, 50% in group B, and 60% in group C. 2. In the patency rate, the ticlopidine group is slightly higher than the aspirin-persantin group and even higher than the control group (P<0.05) in the end-to-end and end-to-side anastomoses. However, the end-to side group is higher in all 3 groups than the end-to-end one (P<0.1). 3. The intimal regeneration in all arteries was completed at end of the third postoperative week in the end-to-end and end-to-side anastomoses. 4. Changes of the internal diameter in anastomosed vessels showed luminal narrowing in the vessels at the third postoperative day and still narrowing at the second and third postoperative week in the end-to-end anastomoses. However, initial postoperative widening continued into the third postoperative week in the end-to-side anastomoses. The authors got a high success rate of anastomoses of very small arteries approximately 0.25 mm in external diameter, by developing a method of using an ordinary microscope and instruments, 11-0 nylon suture, and the administration of ticlopidine hydrochloride which is a more powerful anticoagulant than aspirin-persatin.