• Journal of Aerospace System Engineering
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• v.8 no.2
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• pp.27-32
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• 2014

From the flight safety and the performance point of views, a new engine installation impacts an helicopter development or upgrade program significantly. More than a close relationship between an aircraft manufacturer and an engine manufacturer is necessary for the best integration work from the program initiation phase. In this paper, technical cooperation between aircraft and engine companies, and technical supports by the engine manufacturer for the T700/701K engine during the Surion development program are summarized. The applications of official technical program documents, US Mil-spec, France airworthiness regulations as the standard of the engine installation work, and engineering activities at each phase such as contract, design and manufacturing, flight clearance, ground and flight tests are described. This paper would be a cornerstone for the future domestic helicopter development program.

• Proceedings of the KWS Conference
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• 1999.05a
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• pp.233-236
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• 1999

The welding residual stress should be considered in fatigue stress analysis because it develope during the process of the electric resistance spot welding and it causes bad affect on the fatigue crack initiation and growth at nugget edge of spot welded points. Therefore the accurate estimation of residual stress is crucial. In this study, nonlinear finite element analysis on welding residual stress generated during the process of the spot welding was conducted, and their results were compared with the experimental data measured by X-ray diffraction method. From the results, it was found that welding residual stress existed as tension in the nugget center and as compression around the nugget edge.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.891-896
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• 2000

It is necessary to drill new opening in an existing R.C beam either for service ducts and pipes or the determination of in place concrete strength. Therefore, to simulate in this study, 18-R.C beams were fabricated with circular openings. The major parameters considered are the sizes, location of opening and cut-off stirrup. These beams are tested shear failure and capacity under a point loading. The sizes of opening are changed 0.11, 0.2, 0.3 times of beam-depth and the locations of opening are divided into $X_1$ zone, $X_2$ zone, $X_3$zone. Loads are applied up to failure to observe the cracking initiation and propagation, initial diagonal cracking, midspan deflection. As a result, the sizes of opening with 0.11D and 0.2D in R.C beams without cutoff stirrup are profitable in $X_1$ and $X_3$zone. R.C beams with 0.3D and cutoff stirrup are advantageous in $X_3$zone.

• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.17-23
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• 2006

Monotonic four-point bending tests were conducted on straight pipe specimens, 102 mm in diameter with local wall thinning, in order to investigate the effects of the depth, shape, and location of wall thinning on the deformation and failure behavior of pipes. The local wall thinning simulated natural erosion/corrosion metal loss. The deformation and fracture behavior of the straight pipes with local wall thinning was compared with that of non wall-thinning pipes. The failure modes were classifiedas local buckling, ovalization, or crack initiation, depending on the depth, shape, and location of the local wall thinning. Three-dimensional elasto-plastic analyses were carried out using the finite element method. The deformation and failure behavior, simulated by finite element analyses, coincided with the experimental results.

• KIEAE Journal
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• v.12 no.6
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• pp.11-22
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• 2012

The paper aims to establish planning elements of planned-ecovillages, and analyze the cognizance of residents as well as experts' evaluation so as to examine the awareness of actual residents. The planned-ecovillage allows residents to participate in the organization of the ecovillage to the construction stage. Unlike general ecovillages, planned-ecovillages have a difference as they introduce planning elements by autonomous decision-making through discussions and meetings among residents. The present age is at its turning point. While a fatal impact to human life, including energy shortage and environmental pollution are expected, we may be able to suggest an alternative solution and triggered the initiation, such as a future-oriented ecovillage that enables environmentally-friendly and sustainable living, namely planned-ecovillages.

• Journal of the Korea Safety Management & Science
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• v.9 no.5
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• pp.1-5
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• 2007

We construct the procedure to predict safety accidents following Bayesian approach. We make a model that can utilize the data to predict other levels of accidents. An event tree model which is a frequently used graphical tool in describing accident initiation and escalation to more severe accident is transformed into an influence diagram model. Prior distributions for accident occurrence rate and probabilities to escalating to more severe accidents are assumed and likelihood of number of accidents in a given period of time is assessed. And then posterior distributions are obtained based on observed data. We also points out the advantages of the bayesian approach that estimates the whole distribution of accident rate over the classical point estimation.

• Imaging Science in Dentistry
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• v.48 no.1
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• pp.73-77
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• 2018

Organized hematoma is a pseudo-tumorous lesion mostly occurs at sinonasal cavity and often confused with malignant neoplasm. The initiation of this lesion is blood accumulation, probably due to trauma, and this hematoma develops into organized hematoma as it encapsulated with fibrous band and neo-vascularized. Since it is uninformed at temporomandibular joint (TMJ) region, imaging diagnosis might be challenging. Also, delayed detection of mass involving TMJ is not uncommon due to confusion with joint disorder. Thus, this report introduced the rare pathology, organized hematoma on TMJ with advanced imaging features. Also, diagnostic point for early detection was described for the TMJ tumors and pseudo-tumors considering complexity of surgical intervention in this region.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1142-1147
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• 2006

A practical method for reducing the number of spot welds in automotive structures considering fatigue crack initiation life is suggested. At first, an influence index for the durability and the fatigue life of a spot weld itself is defined and then taken as the main effect of the DOE analysis. Spot welds that can be removed without serious reduction of durability through numerical experiments are selected by the results of DOE. The proposed method was applied to the shock tower and LCA(lower control arm) structure of a vehicle, which are important components in durability-related point of view.

• 한국기계연구소 소보
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• s.20
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• pp.57-63
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• 1990

The morphologies of MC carbides (M stands for metal) and creep-rupture properties in directionally solidified Rene 80 having standard and Hf-modified chemistries were studied. It was found that Hf depressed the melting point, $\gamma$- $\gamma$’ eutectic temperature and $\gamma$’ solvus of nickel-base superalloy Rene 80, but did not depress MC carbide forming temperature. The morphologies of MC carbides depended upon solidification sequence, which led to blocky type in the early stage and script type in the late stage of solidification. Creep failure occurs through the crack initiation at the transverse components of longitudinal grain boundaries or interdendritic carbides in directionally solidified superalloys. It could be concluded MC carbide morphologies played an important role in creep properties of DS superalloys, that is, Hf additions increased the creep ductilities and lives of Rene 80.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1056-1059
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• 1995

The bulk photopolymerization of methyl methacrylate (MMA) with primary arylsilane (e.g., phenylsilane) and various primary alkylsilanes (e.g., benzylsilane, 3-phenoxyphenyl-1-silabutane, 3-naphthyl-1-silabutane, and 3-chlorophenyl-1-silabutane) was performed to produce poly(MMA)s containing the corresponding silyl moiety as an end group. It was found for the phenylsilane that while the polymerization yields increased and then decreased with a turning point at the molar ratio of MMA:silane=10:1 as the relative silane concentration increases, the polymer molecular weights decreased, and the TGA residue yields and the relative intensities of SiH IR stretching bands increased with increment of molar ratio of silane over MMA. The photopolymerization yield of MMA with the arylsilane was found to be higher than those with the alkylsilanes and without the silanes. Thus, the silanes seemed to significantly influence on the photopolymerization as both chain initiation and chain transfer agents.