• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.676-677
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• 2011

Rhenium-Iridium(Re-Ir) thin films were deposited onto the tungsten carbide(WC) molding core by sputtering system. The Re-Ir thin films on tungsten carbide molding core were analyzed by scanning electron microscope(SEM) and surface roughness. The Re-Ir coating technique has been intensive efforts in the field of coating process because the coating technique and process have been their feature, like hardness, high elasticity, adrasion resistance and mechanical stability and also have been applied widely the industrial and biomedical areas. In this report, tungsten carbide(WC) molding core was manufactures using high performance precision machining and the efforts of Re-Ir coating on the surface roughness.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.3
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• pp.135-140
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• 2016

In this study, we developed the solution-processed PMMA-$HfO_x$ hybrid ReRAM devices to overcome the respective drawbacks of organic and inorganic materials. The performances of PMMA-$HfO_x$ hybrid ReRAM were compared to those of PMMA- and $HfO_x$-based ReRAMs. Bipolar resistive switching behavior was observed from these ReRAMs. The PMMA-$HfO_x$ hybrid ReRAMs showed a larger operation voltage margin and memory window than PMMA-based and $HfO_x$-based ReRAMs. The reliability and electrical instability of ReRAMs were remarkably improved by blending the $HfO_x$ into PMMA. An Ohmic conduction path was commonly generated in the LRS (low resistance state). In HRS (high resistance state), the PMMA-based ReRAM showed SCLC (space charge limited conduction). the PMMA-$HfO_x$ hybrid ReRAM and $HfO_x$-based ReRAM revealed the Pool-Frenkel conduction. As a result of flexibility test, serious defects were generated in $HfO_x$ film deposited on PI (polyimide) substrate. On the other hand, the PMMA and PMMA-$HfO_x$ films showed an excellent flexibility without defect generation.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.106-115
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• 1999

Design parameters and goals play important roles in design. Design goals are the required functions of the design elements and explicitly expressed by design parameters. Design parameters also indicate the relations among design elements, by which constraint networks can be constructed and some useful information can be induced. In this study, the mechanical design process is assumed to be the assignment of design goals and their realization through the evolutionary refinement of the design parameters. Thus an integrated design system is proposed to support the process of assigning the design goals and refining the values of the design parameters. In the design system, a genetic engine that utilizes a genetic algorithm is installed to simulate an iterative design process, which leads to an evolutionary design. The genetic engine treats design parameters as genes and design goals as evaluation function. Re-design and design modification are facilitated by the design parameters. The re-design can be activated in the design system by using the information stored in the design parameters when design parameters or goals are changed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.1-6
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• 2017

Gear tooth micro-geometry modifications include the intentional removal of material from the gear teeth flanks, so that the shape is no longer a perfect involute. If the gear shapes are perfect, then the gear tooth meshing is better, therefore the gears will transmit input torque in a more efficient manner without the generation of high frequency engine fluctuation noise. In this paper, we study tooth micro-geometry optimization of rear gear set in 2 speed planetary gear reducers. Analysis revealed problems which are need of modification. Based on the results, tooth micro-geometry was used to deal with load distributions on the rear gear set.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.5
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• pp.415-420
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• 2018

The development of sail gas has increased the production of ethane as well as natural gas. The decline in the market price for ethane has led to a change in the petroleum-based ethylene production process into an ethane-based ethylene production process and an increase in the ethane/ethylene trade volume. Large-scale ethane/ethylene carrier have been needed due to an increase in long-distance trade from the US, and cargo type change have leaded to consider a liquefaction process to re-liquefy Boil-Off gas generated during the voyage. In this paper, the liquefaction system of Liquefied Ethane Gas carrier was evaluated with Low-GWP (Low-Global Warming Potential) refrigerant and process parameters, Boil-Off Gas pressure and expansion valve outlet pressure, were optimized. Low-GWP refrigerants were propane (R290), propylene(R1270), carbon dioxide(R744) was considered at two type of liquefaction process such as Linde and cascade cycle. The results show that the optimal pressure point depends on the individual refrigerant and the highest liquefaction efficiency of carbon dioxide (R744) - propane (R290) refrigerant.

• Journal of Powder Materials
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• v.25 no.3
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• pp.213-219
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• 2018

We report a method for preparing rare earth oxides ($Re_xO_y$) from the recycling process for spent Ni-metal hydride (Ni-MH) batteries. This process first involves a leaching of spent Ni-MH powders with sulfuric acid at $90^{\circ}C$, resulting in rare earth precipitates (i.e., $NaRE(SO_4)_2{\cdot}H_2O$, RE = La, Ce, Nd), which are converted into rare earth oxides via two different approaches: i) simple heat treatment in air, and ii) metathesis reaction with NaOH at $70^{\circ}C$. Not only the morphological features but also the crystallographic structures of all products are systematically investigated using field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD); their thermal behaviors are also analyzed. In particular, XRD results show that some of the rare earth precipitates are converted into oxide form (such as $La_2O_3$, $Ce_2O_3$, and $Nd_2O_3$) with heat treatment at $1200^{\circ}C$; however, secondary peaks are also observed. On the other hand, rare earth oxides, RExOy can be successfully obtained after metathesis of rare earth precipitates, followed by heat treatment at $1000^{\circ}C$ in air, along with a change of crystallographic structures, i.e., $NaRE(SO_4)_2{\cdot}H_2O{\rightarrow}RE(OH)_3{\rightarrow}RE_xO_y$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.828-829
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• 2010

Rhenium-Iridium(Re-Ir) thin films were deposited onto the tungsten carbide(WC) molding core by sputtering system. The Re-Ir thin films on tungsten carbide molding core were analyzed by scanning electron microscope(SEM) and surface roughness. The Re-Ir coating technique has been intensive efforts in the field of coating process because the coating technique and process have been their feature, like hardness, high elasticity, adrasion resistance and mechanical stability and also have been applied widely the industrial and biomedical areas. In this report, tungsten carbide(WC) molding core was manufactures using high performance precision machining and the efforts of Re-Ir coating on the surface roughness.

• Resources Recycling
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• v.32 no.2
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• pp.43-51
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• 2023

In this research, through LCA analysis, the environmental impact of automotive engine manufacturing and re-manufacturing was analyzed from the perspective of the entire process, and the greenhouse gas reduction effect was calculated based on this. The amount of greenhouse gas emitted from the process of acquiring and manufacturing raw materials for automotive engines is about 3,473 kg for new manufacturing and 872 kg for re-manufacturing. Thus, the amount of greenhouse gas reduction by engaging in re-manufacturing is about 2,601 kg; the analysis shows a reduction effect in each part of the entire process except for the processing stage. As a result of the LCA weighted analysis, the environmental impact of new product manufacturing was found to be 1.07E+03 Eco-point, and it was 2.67E+02 Eco-point for re-manufacturing. The share of GWP(Global Warming Potential) among the six major impact categories(Abiotic Depletion Potential, Acidification Potential, Eutrophication Potential, Global Warming Potential, Ozone-layer Depletion Potential, Photochemical Oxidant Creation Potential) as high at 99.72%(new manufacturing) and 99.68%(re-manufacturing).

• Journal of the Korean Society of Systems Engineering
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• v.13 no.1
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• pp.25-31
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• 2017

This paper aims to evaluate the conservatism in the design of APR1400 (Advanced Pressurized water Reactor 1400 designed by KHNP) reactor internals component, the LSS (Lower Support Structure). Re-engineering of the LSS is done based on the system design condition data and applicable ASME code that was used for the original APR1400 design. Systems engineering approach is applied to design the LSS of APR1400 without refering APR1400 LSS dimensional parameters and tries to verify important design parameters of APR1400 LSS as well as the validity of the re-engineering design process as independent verification method of reactor component design. Systems engineering approach applied in this study following V-model approach. The re-engineered LSS design showed more than enough conservatism for static loading case. The maximum deflection of LSS is under 1mm (calculated value is 0.25mm) from 4000 mm diameter of LSS. Hence the deflection can be ignored in other reactor internals for structural integrity assessment. Especially the effect of LSS deflection on fuel assembly can be minimized and which is one of the main requirements of LSS design. It also showed that the maximum stress intensity is 2.36MPa for the allowable stress intensity of 60.1 MPa. The stress resulted from the static load is also very small compared to the maximum allowable stress intensity, hence there is more than enough conservatism in the LSS design.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.1
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• pp.6-14
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• 2011

The re-crystallization process for recovering granular crystalline gypsum from phospho-gypsum have proposed. The process consists of two stages; at the first stage, needle-like fine gypsum is recovered with under-product of 325 mesh wet screening after the speedy hydration of dehydrated phospho-gypsum, and at the second stage, granular crystalline gypsum is recovered with upper-product of 325 mesh wet screening after dehydration and re-crystallization of the needle-like fine gypsum in $Na_2SO_4$ solution. This paper is mainly focused on the influence of dehydration time, cooling speed of temperature and re-crystallization temperature on the recovery of granular crystalline gypsum. And the re-crystallization velocity of needle-like fine gypsum at room temperature and the variation of $Ca^{2+}$ concentration of gypsum slurry during over all re-crystallization process were also discussed.