• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.354.1-354.1
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• 2014

Hafnium nitride (HfN) 박막은 고온에서의 안정성과 낮은 비저항 그리고 산소확산에 대한 억제력을 가지고 있기 때문에 확산방지막으로 많은 연구가 진행 되고 있다. 현재까지 진행된 대부분의 연구는 HfN 박막의 전기적인 특성과 구조적인 특성에 대한 것이었고 다양한 연구 결과가 보고되었다. 하지만 기존의 연구들은 박막의 nano-electrotribology 특성에 대한 연구가 부족하여 박막 적층 공정시 요구되는 물성에 대한 연구가 절실하다. 따라서 본 연구에서는 HfN 박막의 증착조건 및 열처리조건에 따른 nano-electrotribology 특성 변화를 확인하고자 하였다. HfN박막은 rf magnetron sputter를 이용하여 Si 기판위에 Hf target으로 질소 유량을 변화시키며 증착하였고 가열로에서 $600^{\circ}C$와 $800^{\circ}C$로 20분간 열처리를 실시하였다. 열처리한 박막과 as-deposited 상태의 박막을 nano-indenter를 통하여 나노기계 전기적인 특성을 분석하였다. nano-indenter는 박막에 인가된 stress와 탄성계수(elastic modulus), 표면경도(surface hardness)와 같은 특성을 직접적인 tip 접촉을 통하여 in-situ로 분석할 수 있는 장비이다. 실험결과 HfN박막을 $600^{\circ}C$로 열처리 한 경우 표면경도가 16.20에서 18.59 GPa로 증가하였다. 표면경도의 증가는 열처리 시 박막내에 compressive stress가 생성되었기 때문이라고 생각된다. 그러나 $800^{\circ}C$로 열처리 한 경우 표면경도가 16.93 GPa로 감소하였는데 이는 표면균열 발생으로 인한 stress relaxation 때문인 것으로 생각된다. 증착 시 주입되는 질소의 유량과 열처리 온도는 HfN박막의 기계적 안정성에 영향을 미치는 중요한 요소임을 본 실험을 통해 확인하였다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.6
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• pp.770-778
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• 1996

A rapid and economical method of simultaneous extraction of DNA and RNA from seaweeds has been developed by the use of lithium chloride. Lithium chloride facilitates the softening of cell walls resulting in a decrease in both compressive and tensile modulus of elasticity. The DNA was characterized by high molecular weight larger than 27 kb and a relative lack of carbohydrate and protein contamination. The DNA and RNA extracted by the method from many seaweeds were of sufficient quality to be used as a template for per amplification with a plant intergenic gene primer set, for RAPD analysis with arbitrary primers, and for differential display with arbitrary primers in the morphologically distinct regions of the matured Porphyra thallus. The cDNA polymorphism indicated that the reproductive tissue types (male, female, patch) had a relatively high degree of similarity; the vegetative tissue types (dividing, non-dividing) also showed a similar pattern with respect to each other. Holdfast tissue had very low similarity with the other tissues, but appeared most similar to vegetative non-dividing tissue type.

• Journal of the Korean Wood Science and Technology
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• v.26 no.1
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• pp.70-75
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• 1998

In this paper, the relationships between volumetric mixing ratio of rubber chip and physical and mechanical properties of wood/rubber composite panel was examined in order to investigate the mixture characteristics of wood and rubber chip. Because of the specific gravity of rubber differed from wood chip, physical properties of wood/rubber composite panel was shown very different values by mixing rate of chip element. Specific gravity in air-dry of composite panel was increased rapidly as volumetric percent of rubber chip was increased. Moisture content of composite panel was decreased as volumetric percent of rubber chip element was increased. This results was considered that wood weight is light and porosity material for moisture absorption. Compressive strength and modulus of rupture in bending test were decreased as volumetric percent of rubber chip increased. By mixing ratio control of chip elements, various wood/rubber composite panel can be applicable to every interior materials such as subfloor, playground, and exterior materials such as road blocks for recreational facilities in garden and forest and city parks.

• Journal of Powder Materials
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• v.13 no.2 s.55
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• pp.102-107
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• 2006

Recycling industrial wastes such as fly ash from a coal burning heat power plant and shell from an oyster farming were investigated to prevent environment contamination as well as to enhance the value of recycling materials. In this study, the lightweight aggregates and the red bricks were fabricated from fly ashes with other inorganic materials and wastes. The starting materials of the lightweight aggregate were fly ash powder and water glass, and the compacts of these materials were heat treated at $1100^{\circ}C$. The fabricated lightweight aggregates had low bulk density, $0.9-1.2\;g/cm^3$, hence floated on the water and had the strength of 7.0-11.0 MPa and the modulus of 2900-3300 MPa which indicates it has enough strength as the aggregate. Another type of the light weight aggregate was prepared from fly ashes, shell powders and clays. The bulk density, porosity, and compressive strength of these aggregates were $1.19-1.34\;g/cm^3,\;18.3{\sim}56.1%$ and 5-12 MPa, respectively. The addition of a small amount of fly ash powder prevented hydration of the light weight aggregates. The red brick was also fabricated from the fly ash containing materials. It is suitable for the brick facing of a building as it has moderate strength and low water absorption rate.

• Proceedings of the Korean Geotechical Society Conference
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• 1993.06a
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• pp.83-116
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• 1993

This article analyzed the dynamic compaction incuced vibration of man made waste landfill. General dynamic properties and compaction-condition-related dynamic properties were analyzed. from the results, it was turned out that the shear modulus G=17496-58320 t/m2, dannpln ratio D=14~58%, dominant frequency f=6-14Hz. Also, it was turned out that the propagation velocitis of low amplitude shear wave and compressive wave were increased as the number of impact increased, the relation between peak particle velocity, and impact distance was wpp=5.08.[D/r E]-1.4, the peak particle velocity was high at the lower part of the waste fill layer and the range of dynamically improved area was about 6-10m.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.571-578
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• 1997

In the repair and repair works, epoxy resins are widely used as repair materials. The successful concrete repairs and retrofit works depends on the quality of the repair and retrofit materials. Although many materials for the repairs and retrofit have been developed in many contries, information on the repair methods are somewhat limited. Futhermore, the repairs and retrofit methods are also largely dependent on those froms in other developed contries, it is necessary to initiate rather fundamental repair-related research. The purpose of this study is to investigate th physical and mechanical properties of epoxy resin which is commonly used in repairing concrte crack in RC structures. The basic physical properties such as specific gravity, gel point and shrinkage ratio as well as the mechanical properties such ad the tensile and compressive strength, elastic modulus were acquired by the standard test method (KS code). For the test results, the great deviations of physical and mechanical properties among the test materials were discovered and is, therefore, recommended that careful attentions should be give in selecting the epoxy resin by considering the characteristics of the repair materials and repair works.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.225-228
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• 2005

This paper was accomplished for analyzing the reason of the above deterioration happened on the deck of concrete bridge. The bridge was constructed at 660m above the sea level having more freezing and snowing days. Therefore, it is placed on the particular condition sprinkling $CaCl_2$ enough for keeping up with moderate traffic condition. When it is considered to the former condition, the bridge can be assumed to potentialities for combined deterioration with freezing-thawing under sprinkling deicing chemical. Core specimens were gathered from the concrete deck for clearing the reason of the above deterioration exactly, and it is used for various tests for measuring the compressive strength, elastic modulus, content of $Cl^-$, freezing-thawing at the fresh and salt water. As a result of freezing-thawing test, the specimen at the fresh water has over 90$\%$ of durability factor, but another specimen at 1$\%$ of salt water has 0$\%$ of durability factor at 140 cycles of the freezing-thawing. The result means that frost damage is sccelerated at the salt water. Therefore, the deterioration of the concrete deck is estimated to be occured by combined effects of freezing-thawing and chloride ion attack.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.469-472
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• 2005

With all ensuring the fire resistance structure as a method of setting the required cover thickness to fire, the RC is significantly affected from the standpoint of its structural stability that the compressive strength and elastic modulus is reduced by fire. Normally, the degradation of concrete member exposed to fire is largely dependent on the fire scale and fire condition. There is therefore a need to precisely predict the deterioration and fire damage of the exposed member. Thus, this work estimated the temperature distribution inside a member taking into consideration of the thermal properties by means of finite element method(FEM). The estimation results in a little higher prediction value than the experimental value in surface layer and is almost coincident with the experiment as the heating depth increase. From this work it can be known that the simulation application of FEM using the thermal properties of concrete member in high temperature gives rise to the confident prediction in the prediction of temperature distribution.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.857-860
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• 2008

This study shows systematic procedures for investigating creep and shrinkage properties of 50, 60, 70 MPa concrete mixes, which were developed by Lotte E&C R&D Ins. for Lotte Super Tower Jamsil. The concrete test was performed both local and foreign laboratory, S-Lab. and CTL Group respectively. The former have done for total five days. The procedures included the followings, specimen fabrication, mold removal, specimen marking, water bath curing, packaging, and shipment. The latter has been doing by CTL within PCA(Portland Cement Association). They are testing on static and dynamic modulus of elasticity, compressive strength, creep & shrinkage, splitting tensile strength. In the case of creep and shrinkage, the test will be doing for 18 months according to each loading age.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.72-79
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• 2007

This study investigates the engineering properties of concrete incorporating lime stone crushed fine aggregate(Ls), which has been abandoned about 20% of total production due to the low purity. Test results showed that increase of Ls had favorable fluidity and slightly decreased air content. Bleeding capacity of all specimens was not appeared as those were high strength mixture proportion, but the specimens using more Ls accelerated initial and final setting. For the mechanical properties, specimens incorporating higher ratio of Ls, overall, resulted in increase of compressive strength, and exhibited very small inclined tendency in a dynamic elasticity modulus test In addition, for the durability properties, specimens incorporating higher Ls dramatically decreased a drying shrinkage and showed similar tendency in a frost & thaw test, as well as showing no more change in an accelerated neutralization test from the beginning. In conclusion, as it was confirmed in the experimental test, the high strength concrete applying Ls did not showed any problems in the aspects of engineering properties and mostly exhibited even more excellent quality than the specimens using natural fine aggregate.