• 한국도로학회논문집
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• 제15권4호
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• pp.177-186
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• 2013

PURPOSES: The purpose of this study theoretically reviews vertical grade deriving process in super high speed environment and compares overseas design criteria with Domestic Standardization also draws suitable vertical grade design criteria of high standard for Domestic Circumstances in Korea. METHODS : By researching domestic vehicle registration status, calculating typical vehicle, using Vissim which is traffic simulation program, Speed-distance curve of the vehicle is derived under each design speed condition. Through Speed-distance curve, estimating critical length of grade and considering critical length of grade, maximum longitudinal incline is proposed. RESULTS : The result of domestic vehicle registration status, the typical vehicle for deriving vertical grade is calculated based on gravity horsepower ratio 200 lb/hp. For calculating critical length of grade, according to change speed of uphill entry, speed-distance curve is derived by using Vissim. Critical length of grade is calculated based on design speed 20 km/h criteria which is point of retardation. Estimated critical length of grade is 808 m and based on this result, maximum longitudinal incline was confirmed in the design speed between 130km/h to 140km/h. CONCLUSIONS: The case of the typical vehicle(truck) which is gravity horsepower ratio 200 lb/hp, maximum longitudinal incline 2% is desirable at the super high speed environment in the design speed between 130km/h to 140km/h.

• 한국작물학회지
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• 제7권1호
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• pp.117-121
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• 1969

춘파과맥 ${\ulcorner}$완주봄보리${\lrcorner}$의 종자를 5~100ppm의 지벨레린의 용액에서 백체출현기까지 최아하여 발아 및 포장시험을 실시한바 그 성적을 요약하면 다음과 같다. 1. 지벨레린최아에 으하여 발아율의 감퇴없이 2 (상온구)~3일(저온구)의 발아촉진을 보였다. 2. 지벨레린최아를 하면 초기생육촉진이 일면으로는 주장적현상이 현저하였는데 그경향은 고농도 일수록 심하다. 3. 지벨레린최아로 근생장의 억제작용은 전연 인정되지 않았다. 4. 포장조건에는 발아촉진의 효과가 별로없었고 고농도처리에서는 발아율의 감퇴를 초래하여 수수감소 및 수량감소를 초래하였다. 5. 고농도일수록 초기의 주장화경향이 심하고 회복도 늦으나 생육중기에 가서는 거의 모두 정상으로 회복되며, 따라서 출수 성숙 및 간장이 처리에 의한 변이를 보이지 않았다. 6. 5~10ppm의 농도에서는 발아저해가 적고 초기의 주장화경향이 적으며 수수감퇴도 적은 반면에 수장이나 천립중은 증대경향이어서 결과적으로 중수경향을 보였으나 재 검토가 필요하다. 7. 지벨레린 최아만으로는 발아촉진은 기대되나 조숙화는 기대되지 않는다.

• 한국전산구조공학회논문집
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• 제25권3호
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• pp.267-275
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• 2012

본 연구에서는 모드 I의 변동진폭하중 하에서 평판의 두께관통 균열성장을 예측하고 예측결과를 실험을 통해 검증하였다. 균열성장 모델을 위해 과하중으로 인한 균열가속과 지연효과를 고려하는 Huang의 모델식을 이용하였다. 실험적 검증을 위해 Al6016-T6 평판 균열을 제작하여 변동하중을 부여하고 균열길이를 일정 주기로 육안 측정하였다. 측정데이터로부터 모델 변수를 추정하기 위해 베이지안 접근법에 기반한 파티클 필터 방법을 이용하였고, 이를 통해 위험크기까지의 미래 거동 및 잔존수명을 확률적으로 예측하였으며, 이를 실제 실험한 결과와 비교하였다. 그 결과 변동하중에 의한 균열지연이 잘 예측됨을 확인하였고, 측정 데이터가 증가할수록 예측된 중앙값(median)이 실제와 점점 더 일치하였다.

• 환경생물
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• 제22권2호
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• pp.321-328
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• 2004

The effects of Di (2-ethylhexyl) phthalate (DEHP) on the fourth instar larvae of Chironomus riparius were tested in the laboratory. Employing a waterreplacement exposure setup, chironomids were subjected to various concentrations. In the most treatments mortality reached a statistically significant difference from the control conditions. As DEHP concentrations were increased, the rates of emerged adults decreased. Sex ratio was unaffected with little deviation from a 1:1 relationship (except in 1 and $30\mu{g}\;L^{-1})$. The developmental stages was delayed at low concentration (0.3 and $1\mu{g}\;L^{-1})$. Generally the emergent period was different between males and females, and the first emergent day of males was faster than females. The body shape of female adults was larger than males. Differences between males and females were found in body volume, body length and body width. In addition, the body volume showed the significant difference between controls and treatments, and those especially well observed females.

• Korea-Australia Rheology Journal
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• 제13권2호
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• pp.89-95
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• 2001

Effects of particulate size and frictional characteristics were examined on the melting behavior of PP(polypropylene) in a twin screw extruder. Powder and pellet types of PP were used and each component was blended with PE(polyethylene) wax and clay, respectively. It was observed that small size particulates, 1.e. powder systems exhibit accelerated melting behavior; and it was also found that the abrasive auditive acts as an effective agent for fast melting of PP powder. Retardation of melting due to the reduced friction was observed in both types of PP, contrary to the result found in a batch mixer. The tendency observed in variation of torque and exit temperature was explained in terms of frictional effect and length of compacted region formed during evolution of melting.

• International Journal of Precision Engineering and Manufacturing
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• 제2권3호
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• pp.19-26
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• 2001

In order to investigate the effect of single tensile overload on the short crack growth behavior under the out-of-plane cyclic bending moment, crack opening stresses were continuously measured by an elastic compliance method using strain gages. The characteristics of short crack growth after the single tensile overload are analyzed by the effective stress range ratio. Futhermore, the investigation was carried out with respect to various fatigue crack growth behaviors such as the plastic zone size effect on crack retardation, the retarded crack length and the number of cycles.

• Biomolecules & Therapeutics
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• 제22권2호
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• pp.83-92
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• 2014

Fatty acids (FAs) are highly diverse in terms of carbon (C) chain-length and number of double bonds. FAs with C>20 are called very long-chain fatty acids (VLCFAs). VLCFAs are found not only as constituents of cellular lipids such as sphingolipids and glycerophospholipids but also as precursors of lipid mediators. Our understanding on the function of VLCFAs is growing in parallel with the identification of enzymes involved in VLCFA synthesis or degradation. A variety of inherited diseases, such as ichthyosis, macular degeneration, myopathy, mental retardation, and demyelination, are caused by mutations in the genes encoding VLCFA metabolizing enzymes. In this review, we describe mammalian VLCFAs by highlighting their tissue distribution and metabolic pathways, and we discuss responsible genes and enzymes with reference to their roles in pathophysiology.

• Journal of Chest Surgery
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• 제25권9호
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• pp.925-929
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• 1992

Supravalvular aortic stenosis is relatively uncommon form of congenital heart disease and the most important lesion of this anomaly is various narrowing of the aortic lumen just above the sinus of Valsalva. We experienced a case of hourglass type of supravalvular aortic stenosis involving lcm from length from lcm above the sinus of Valsalva. The patient was associated with mental retardation, peculiar facies and dental anomaly. The diagnosis was confirmed preoperatively by retrograde left heart catheterization and left ventriculography. An incision was made in the ascending aorta and into the right coronary and noncornary sinus. Care was taken to protect the right coronary artery. A Y-shaped patch of Dacron was made to enlarge the stenotic portion of aorta. Postoperative pressure gradient between the aorta and left ventricle markedly reduced 36 mmHg in comparison with preoperative pressure gradient 150mmHg. The boy was discharged without any event.

• 한국세라믹학회지
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• 제31권10호
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• pp.1107-1114
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• 1994

Although various theories have been presented on the mechanism of setting retardation of plaster in addition to organic admixtures. The purpose of this paper is that Hydration studies of plaster of paris in the presence of carboxylic acids under alkalinity are examined in the coordination chemistry. Setting of plaster of paris is retarded by the addition of carboxylic acids except oxalic acid. And setting of plaster of paris contained 5 wt% of Ca(OH)2 is also retarded by the addition of above-mentioned carboxylic acids. The degree of retarding effect under alkalinity is found to be a function of the number of the functional group and the length of carbon chain of carboxyl acids. These reasons are attributed to the soluble complex formation, that is calcium complex formation between calcium ion and carboxylic acids. The author's proposal was confirmed by the results of electrical conductivity measurement. The formation of calcium complex was surpported by IR spectra.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.834-840
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• 2008

We carried out fatigue testing with materials of aluminum alloyC7075-T6, 2024-T4) by rotary bending fatigue tester. We investigated fatigue limit, fatigue crack initiation, fatigue crack propagation behavior and possibility of fatigue life prediction to the different small circular hole defect. The summarized result are as follows; Fatigue limit of the smooth specimens were related tensile strength and yield strength. In case of more large applied stress and small circular hole crack defect, the fatigue crack was grown rapidly. The fatigue crack propagation behavior proceed at according to inclusion. Fatigue crack propagation ratio appeared instability and retardation phenomenon in the first half of fatigue life but appeared stability and replied in the latter half. On other hand, this experimental data of the materials are appeared fatigue life predictability.