레이저를 이용한 Tailored Blank 용접 판재의 피로거동

오택열,권윤기,이종재,곽대순 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.4

For the Tailor Welded Blank sheet used for automobile body panel, the characteristics of fatigue strength and crack propagation behavior were studied. The thickness of specimen was joined to be same (0.9mm+0.9mm) and different (0.9mm+2.0mm). As a base test, mechanical properties around weld zone were examined. The results indicated that there were no significant decreases in mechanical properties, but hardness around weld bead was 2.3 times greater than base material. The fatigue strength was the highest when the loading direction was parallel to the welding direction, which was about 85% of tensile strength of base metal. It was decreased by 8.5% when the thickness of specimen and base metal was different, and it was increased by 25% when pre-strain was applied. The crack propagation rate was noticeably decreased around weld line and rapidly increased as it passed through weld line. Reviewing the shape of the crack propagation, crack width around weld line was wide around the weld zone due to retardation of crack growth, but it became narrow passing weld line due to decreased toughness.

Grade 2, 4 티타늄 마이크로 임플랜트의 식립 및 제거 토크와 식립 후 조직학적 반응의 비교

강승택,권오원,성재현,경희문,박효상 대한치과교정학회 2006 대한치과교정학회지 Vol.36 No.3

마이크로 임플랜트는 순티타늄과 티타늄 합금을 사용하고 있다. 순티타늄의 경우 grade가 낮을 수록 생체적합성은 증가하나 기계적 성질이 낮다. 이에 본 연구에서는 순티타늄 grade 2와 grade 4를 재료로 한 마이크로 임플랜트를 각각 토끼의 다리뼈에 식립한 후 2, 8, 12주의 시간경과에 따른 조직학적 소견의 차이와 식립, 제거 시의 최대토크의 측정으로 그 티타늄 종류에 따른 차이를 살펴보았다. 토끼의 경골에 식립한 티타늄의 종류에 따른 식립시 및 시간의 경과에 따른 제거시의 토크를 측정하여 다음과 같은 결론을 얻었다. 첫째, grade 2와 grade 4간의 식립 시 최대토크의 차이는 없었다. 둘째, 식립 후 2, 8, 12주 후의 제거 시 최대토크 측정에서 전체 마이크로 임플랜트의 그룹간 차이는 없었다. 셋째, 2주에서 8주로 시간이 경과함에 따라 제거 시 최대토크가 유의하게 증가하였으며 8주와 12주간에는 유의한 상관관계가 없었다. 따라서 유지력은 grade 2 티타늄과 비슷하지만 물리적 성질이 더 단단한 grade 4 티타늄을 마이크로 임플랜트 재료로 사용하는 것이 좋은 것으로 생각된다. The purpose of this study was to evaluate the light microscopic features and the maximum insertional and removal torque value of microimplants, made from titanium grade 2 or 4, in the tibia of 6 rabbits. First, the maximum torque values of microimplants at implantation were measured. After 2, 8, and 12 weeks of healing time, the microimplant-containing segments of tibia of 2 rabbits were removed and the maximum removal torque of each microimplant were measured. Comparisons of histologic examination and insertional and removal torque values were carried out for the two groups of microimplants. Removal torque values were significantly increased in both groups after 8 and 12 weeks as compared to 2 weeks after implantation. Other values measured did not show any statistically significant differences and there were no histological differences between grade 2 and 4 titanium. Based on these results, this study showed that there were no significant differences between grade 2 and 4 titanium. It seems better to use grade 4 titanium for making microimplants because grade 4 titanium is mechanically harder than grade 2 titanium and has similar retention.

한국산 감귤 수입 예상국의 수입 검역제도에 관한 연구

김택조,강영길,권오균 濟州大學校 亞熱帶農業硏究所 1995 亞熱帶農業硏究 Vol.12 No.-

수출밀감 생산지와 밀감 수출관련기관에 유용한 정보를 제공하고자 제주산 온주밀감 주요수입국 및 수입가능국의 검역제도를 조사분석한 결과를 요약하면 다음과 같다. 1. 조사대상국의 연간 수입량은 캐나다 61.5천톤, 미국 101.1천톤, 일본 1.2천톤, 홍콩 32.3천톤 정도이었고 1993년 한국산 감귤 수입량은 캐나다 1107톤, 홍콩 6톤, 러시아가 150톤이었다. 2. 캐나다는 병충해 위험도 평가를 실시한 후 한국산 밀감을 식물위생증이나 수입허가서 없이 수입하고 있다. 수입검사 중 캐나다에 분포하는 병해충으로서 감염정도가 심하지 않은 식물류는 소독처리하고 캐나다에 분포하지 않은 병해충이나 분포하는 병해충이라도 감염이 심한 경우 폐기 (반송)된다. 한국산 밀감의 경우 부패과를 제외하고는 검역상 문제가 되지 않고 있다. 3. 미국은 수입허가제를 채택하고 있으며 한국산 밀감은 궤양병, 흑반병, 화살깍지벌레의 미국내 유입을 막기위하여 수입이 금지되고 있으나 궤양병 무병 생산단지 및 완충지대 설정, 과실의 예방적 소독처리, 박테리아제 테스트 실시, 선과 후 안전조치등을 조건으로 미국내 수입이 한미간 합의 되었다. 과실의 채소류의 반입항에서 수입물량의 약 2%의 임의 표본 추출하여 검사하며, 미국에 분포하는 병해충만이 검출되는 경우에는 수입이 가능한 반면 검역대상 병해충이 발견될 때 소독방법이 있을 경우에는 소독하고 소독방법이 없을 경우에는 폐기 또는 수입이 거부된다. 4. 일본은 14종의 금지병해충의 기주식물 및 식물성 생산물의 수입을 금지하고 있으나 한국산은 수입금지품에 해당되는 식물이 없다. 금지병해충 (14종)과 특정 중요병해충 (42종)이 부착된 식물중 효과적인 소독방법이 확립되어 있지 않은 과실은 폐기되고 소독가능 병해충이 발견된 과실류는 소독되거나 선별된다. 5. 홍콩에서의 수입 비제한 품목인 과실 및 채소류는 식물위생증이나 수입허가서 없이 수입되며 수입검사중 병해충이 발견되면 소독처리된다. 6. 러시아에서는 수입비제한 품목을 제외하고는 식물 및 식물성 산물의 수입시 식물위생증과 수입허가서가 요구되며 허가항을 통하여 수입되어져야 한다. 7. 감귤류가 재배되지 않아 수입검역이 까다롭지 않은 캐나다, 홍콩, 러시아의 동부에 한국산 밀감 수출 증대를 도모하는 것이 바람직하다. This study was conducted to obtain knowledge of import quarantine system in Canada, the U.S.A., Japan, Hongkong and Russia, which may facilitate export Korean mandarins to these countries. The results are summarized as follows : 1. Canada, the U.S.A., Japan, Hongkong annually import about 61,500, 101,100, 1,200 and 32,300 tons. respectively, of such citrus fruits as mandarins, tangerines and clementines. In 1993, 1,107 tons of Korean mandarins were imported into Canada, 6 tones into Hongkong and 150 tones into Russia. 2. After pest risk on Korea mandarins for Canada was assessed, the mandarins have been imported into Canada without phytosanitary certificate and import permit. When either diseases and/or pests which have occurred in Canada are found or they are not severe during import inspection, disinfection is ordered. When either diseases and/or pests which have never occurred in the country are found or they are severe, the importer is ordered to destroy or reship the shipment. In Canada, import quarantine for Korean mandarins has been smooth except the rotten fruits have been found. 3. The import of Korean mandarins into the U.S.A. is prohibited to prevent citrus caker, phoma rot and arrowhead scale from being introduced into the U.S.A. However, it has been agreed between Korea and the U.S.A. that there can be imports into the U.S.A. of mandarins from Chejudo based on implementation of certain procedures. At the ports of entry, inspections are conducted by sampling about 2% of the imported amount of fruits and vegetabls. When injurious diseases and/or pests are found, disinfection is ordered. When there is no methods of disinfection which can completely kill the diseases and/or pests, the importer is ordered to destroy or reship the shipment. 4. Prohibited are host plants and plant products of 14 kinds of diseases and pests that have never occurred in Japan. In import inspection, when diseases and/or pests are found, disinfection is ordered. When there is no methods of disinfection which can completely kill the diseases and/or pests. the importer is ordered to destroy or reship the shipment. 5. Fresh fruits and vegetable can be imported into Hongkong without phytosanitary certificate and import permit. When diseases and/or pests are found during import inspection, disinfection is ordered. 6. Phytosanitary certificate permit are required in Russia for import of plants and plant products from foreign countries. The port of entry is designated by the quarantine authorities. It seems to be desirable to try hard to increase export amount of Korean mandarins to Canada, eastern Russia and Hongkong which do not raise citrus fruits and are not strict for import quarantine of citrus fruits.

용해성 poly(dimethy-co-diphenylsilane)공중합체의 특성과 열분해에 관한 연구

강필현,양현수,황택성,김봉만,권오현 忠南大學校 産業技術硏究所 1993 산업기술연구논문집 Vol.8 No.2

Soluble poly(dimethyl-co-diphenylsilane)copolymer,[(SiMe₂)x(SiPh₂)1-x]n where x=0.5 to 0.9., was synthesized by condensation polymerization of dimethyldichlorosilane and diphenyldichlorosilane in xylene. In the TG analysis of the copolymer, weight loss started at 170℃ and the weight residue at 1000℃ was 32%. The copolymer was stabilized by thermal oxidation at 80 to 110℃ for 5 hr. in air, and its thermal stability increased as the temperature increased. The copolymer heat treated above 700℃ showed no organic bonds of C-H and Si-CH₃. while Si-C, and Si-O large bonds were observed. Amorphous SiC was obtained by pyrolysis at 1000℃ and β-SiC at 1200 to 1400℃, in which a better crystallinity of β-SiC was observed at a higher temperature.

Hydrophilic and Flexible Polyurethane Foams Using Sodium Alginate as Polyol: Effects of PEG Molecular Weight and Cross-linking Agent Content on Water Absorbency

Kwon, Oh-Jin,Oh, Seung-Taek,Lee, Sang-Do,Lee, Na-Ri,Shin, Chang-Hoon,Park, Jong-Shin The Korean Fiber Society 2007 Fibers and polymers Vol.8 No.4

Hydrophilic and flexible polyurethane foams were prepared using sodium alginate as a polyol, and characterized by optical microscopy, FT-IR spectroscopy, density measurements, volume swelling, and water absorbency. Optical microscopy revealed that the resulting cells were closed with round and elongated shapes. FT-IR confirmed that the urethane linkages were formed between the isocyanate and sodium-alginate. As an indirect measurement of porosity, the apparent density indicated an initial decrease followed by an increase with increasing glycerin content. The volume-swelling ratio was initially constant, followed by a gradual decrease with glycerin content. The volume swelling ratio increased with PEG molecular weight. The water absorbency initially increased, followed by a decrease with increasing glycerin content. The correlation ships between water absorbency, density, and volume-swelling ratio indicated that the absorbency was predominantly influenced by density when the PEG molecular weight was low and was greatly affected by the volume-swelling ratio when the PEG molecular weight was relatively high.

Effects of Somatotropinand Human Vascular Endothelial Growth Factor on the In Vitro Development of Porcine Oocytes using Chemically Defined Medium

Kwon, Oh-Seo,Koo, Ok-Jae,Kwon, Dae-Kee,Kang, Jung-Taek,Oh, Hyun-Joo,Hong, So-Gun,Park, Jung-Eun,Park, Hee-Jung,Kim, Dae-Yong,Lee, Byeong-Chun 한국수정란이식학회 2006 한국수정란이식학회 학술대회 Vol.2006 No.1

Behavioral evidence for geomagnetic imprinting and transgenerational inheritance in fruit flies

Oh, In-Taek,Kwon, Hye-Jin,Kim, Soo-Chan,Kim, Hyung-Jun,Lohmann, Kenneth J.,Chae, Kwon-Seok National Academy of Sciences 2020 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.117 No.2

<P><B>Significance</B></P><P>Although migratory animals, such as salmon and sea turtles, are thought to imprint on their natal magnetic field and use this information to return as adults, direct experimental evidence thereof remains elusive. This study experimentally demonstrates that organisms can imprint a magnetic field and that this imprinting can be inherited by their progeny. Prenatal exposure to a specific geographic magnetic field during development affected adult responses to the matching field gradient through downward movements associated with foraging. This same behavior occurred spontaneously in the progeny of the next generation. These results suggest that imprinting on the magnetic field of a natal area assists magnetoreceptive organisms and their offspring in recognizing locations favorable for foraging and reproduction.</P><P>Certain long-distance migratory animals, such as salmon and sea turtles, are thought to imprint on the magnetic field of their natal area and to use this information to help them return as adults. Despite a growing body of indirect support for such imprinting, direct experimental evidence thereof remains elusive. Here, using the fruit fly as a magnetoreceptive model organism, we demonstrate that exposure to a specific geographic magnetic field during a critical period of early development affected responses to a matching magnetic field gradient later in life. Specifically, hungry flies that had imprinted on a specific magnetic field from 1 of 3 widely separated geographic locations responded to the imprinted field, but not other magnetic fields, by moving downward, a geotactic behavior associated with foraging. This same behavior occurred spontaneously in the progeny of the next generation: female progeny moved downward in response to the field on which their parents had imprinted, whereas male progeny did so only in the presence of these females. These results represent experimental evidence that organisms can learn and remember a magnetic field to which they were exposed during a critical period of development. Although the function of the behavior is not known, one possibility is that imprinting on the magnetic field of a natal area assists flies and their offspring in recognizing locations likely to be favorable for foraging and reproduction.</P>

시화호 상류 기수역에서 시,공간적 수질 분포 특성

오영택 ( Young Taek Oh ),최광순 ( Kwang Soon Choi ),김세원 ( Sea Won Kim ),김동섭 ( Dong Sub Kim ),최동호 ( Dong Ho Choi ),권혁재 ( Hyuck Jae Kwon ),허우명 ( Woo Myung Heo ),권상용 ( Sang Yong Kwon ) 한국물환경학회 2006 공동 추계학술발표회 Vol.2006 No.-

포스터 발표 : 수질관리 ; 시화호 상류 기수역에서 시,공간적 수질 분포 특성

오영택 ( Young Taek Oh ),최광순 ( Kwang Soon Choi ),김세원 ( Sea Won Kim ),김동섭 ( Dong Sub Kim ),최동호 ( Dong Ho Choi ),권혁재 ( Hyuck Jae Kwon ),허우명 ( Woo Myung Heo ),권상용 ( Sang Yong Kwon ) 대한상하수도학회 2006 공동추계 학술발표회 논문집 Vol.2006 No.-

제주도 지하수 질산염 농도의 시·공간적 변화 특성: 장기(1993-2015) 모니터링 자료의 평가

김호림(Ho-Rim Kim),오준섭(Junseop Oh),도현권(Hyun-Kwon Do),이경진(Kyung-Jin Lee),현익현(Ik-Hyun Hyun),오상실(Sang-Sil Oh),감상규(Sang-Kyu Kam),윤성택(Seong-Taek Yun) 대한자원환경지질학회 2018 자원환경지질 Vol.51 No.1

1993년부터 2015년까지 관측된 제주도 지하수 장기모니터링 관측정(N = 4,835)에서 수집된 지하수 수질자료(N = 21,568)를 기반으로 질산성질소의 시공간적 변동 특성을 평가하였다. 제주도 지하수의 질산성질소 농도의 중앙값은 2.5 mg/L로서 다른 국가나 대륙의 조사 결과에 비해 다소 높거나 유사한 것으로 나타났다. 또한 지하수 용도, 행정구역 및 고도 별로 유의한 차이를 보였다. 특히, 산간 지역에 비해 저지대 해안가에 위치한 농업 및 주거지역에서 농도가 높음을 확인하였다. Mann-Kendall 및 Sen’s slope 분석을 활용한 질산성질소 농도의 추세 분석 결과, 하류 저지 대에 비해 중산간지역에서의 질산성질소 농도 증가 경향이 뚜렷하였다. 제주도 내 토지 피복의 시계열 변화 특성과 결부 지어 보면, 중산간지역의 오염 증가 추세는 농업지역의 확장 등 인위적 활동 증가에 기인한 결과로 판단된다. 반면,기지정된 지하수자원특별관리구역에서는 전반적으로 질산성질소 농도의 감소 경향이 나타났는데, 이는 지하수 관리 측면에서 수질관리를 위한 적극적인 정책이 유효함을 시사한다. 본 연구에서는 제주도 지하수의 질산성질소 오염관리를 위한 적정 방안을 제안한다. The spatio-temporal variations of nitrate concentrations in groundwater of Jeju Island were evaluated by an analysis of time series groundwater quality data (N = 21,568) that were collected from regional groundwater monitoring (number of wells = 4,835) for up to 20 years between 1993 and 2015. The median concentration of NO 3 -N is 2.5 mg/L, which is slightly higher than those reported from regional surveys in other countries. Nitrate concentrations of groundwater in wells tend to significantly vary according to different water usage (of the well), administrative districts, and topographic elevations: nitrate level is higher in low-lying agricultural and residential areas than those in high mountainous areas. The Mann-Kendall trend test and Sen’s slope analysis show that nitrate concentration in mid-mountainous areas tends to increase, possibly due to the expansion of agricultural areas toward highland. On the other hand, nitrate concentrations in the Specially Designated Groundwater Quality Protection Zones show the temporally decreasing trend, which implies the efficiency of groundwater management actions in Jeju. Proper measures for sustainable groundwater quality management are suggested in this study.