• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 2000년도 하계 학술대회 논문집
• /
• pp.130-135
• /
• 2000

• 한국분말재료학회지
• /
• 제18권1호
• /
• pp.29-34
• /
• 2011

In order to increase the coercivity of (Nd, Dy)-Fe-B sintered magnets without much reduction of remanence, small amount of Dy compounds such as $Dy_2O_3$ and $DyF_3$ was mixed with (Nd, Dy)-Fe-B powder. After mixing, the coercivity of (Nd, Dy)-Fe-B sintered magnets apparently increased with the increase of Dy compound in the mixture. Addition of $DyF_3$ was more effective than $Dy_2O_3$ for the improvement of coercivity. Reduction of the remanence by the addition of Dy compound, however, was larger than expected mostly due to unresolved coarse Dy compound in the magnet. EPMA analysis revealed that Dy was diffused throughout the grains in the magnet mixed with $DyF_3$ whereas Dy was rather concentrated around grain boundaries in the magnet mixed with $Dy_2O_3$.

• 한국산업보건학회지
• /
• 제7권1호
• /
• pp.3-18
• /
• 1997

This study was conducted to evaluate desorption efficiencies by types of desorption solvent for polar and non-polar organic compounds collected on activated charcoal tubes. Analytes tested were toluene, m-xylene, isobutyl alcohol, n-butyl alcohol, cellosolve acetate, and butyl cellosolve. Three different concentration levels of spiked sample were made. Types of cosolvent mixed with the main solvent, $CS_2$, were methanol, pentanol, and dimethylformamide (DMF) and the cosolvent for methylenechloride was methanol. The amounts of cosolvent added to the main solvent were 1, 5, and 10% by volume (v/v%), respectively. The results were as follows: 1. For all mixed solvents except 1% methanol and 1% pentanol with $CS_2$, desorption efficiency significantly increased, compared with that of $CS_2$ alone. 2. Desorption efficiency increased by increasing analyte loading on charcoal tube regardless of mixed solvents used and the material polarity. 3. For all cosolvents mixed with $CS_2$ by 1% and 5% volume, desorption efficiency for non-polar compound was significantly higher than that of polar compound. For the 10% mixed solvents and the methylenechloride mixed with methanol, the results were opposite. 4. The lowest mean percent bias of 4.79% was obtained from the 5% DMF-$CS_2$ mixed solvent, followed by 4.82% from the 10% DMF-$CS_2$ solvent while the highest bias of 23.26% was from the solvent of $CS_2$ alone. Based on the results of this study, in order to increase desorption efficiency, it is recommended to add such cosolvents as methanol, pentanol, and DMF to $CS_2$, preferably 5% by volume for analyzing polar compounds collected in charcoal tubes.

• Restorative Dentistry and Endodontics
• /
• 제22권2호
• /
• pp.739-750
• /
• 1997

Treatment of root perforation elicits special considerations due to its blood-contaminated circumstances. It is known that conventional dental restorative materials are all leaking. Calcium sulfate is the material which react with water to become chemically set. This study, therefore, was performed to develop a new compound containing calcium sulfate and to evaluate its physical and biological characteristics. Three materials were used, IRM, calcium sulfate, calcium sulfate-hydroxyapatite compound. The composition of the calcium sulfate-hydroxyapatite compound was basically 50 % of calcium sulfate and 50 % of hydroxyapatite mixed with guajacol. The materials were mixed in conventional way and underwent four physical test procedures, setting time, solubility test, compressive strength, and marginal leakage test. All materials were evaluated under the scanning electron microscope to examine the marginal sealing ability. Animal experiment was also performed to test the materials' tissue response. Twenty-four dog's premolars were tested with either furcation perforations or apical retro-fillings. From the results, we found that calcium sulfate possess the good marginal sealing ability. However, calcium sulfate creates many voids which is caused by crystal thrusting action when it reacts with water. It seemed that the voids caused disintegration of the material which eventually lead to tissue reaction. By compounding calcium sulfate and hydroxyapatite, we were able to obtain the better physical properties but it showed larger marginal gap between the material and the root surface. Within the six weeks observation period, both IRM and calcium sulfate-hydroxyapatite compound showed good tissue responses in animal experiment. It is concluded that calcium sulfate would be the material of choice in root perforation repair, but the physical property needs to be further improved.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
• /
• pp.497-500
• /
• 2004

Recently, the use of structure compound waterproof agent (hereinafter referred to as 'SCWA') that is used when manufacturing concrete for concrete structures, increases in quantity. However, while it is expected that the SCWA that is mixed in the concrete inside can significantly affect the change of physical properties that lift the internal force of a structure. This study has been conducted through an experiment for the effects of cement hardener on the formation of microscopic texture, and newly generated hydrates from that result were not confirmed in the present experiment. It was found that at the hydrate reaction it has the property that can be hardened within the limit of pore diameterar a specific size rather than there is the internal gap filling capacity due to generating other hydrates.

• 응용통계연구
• /
• 제22권1호
• /
• pp.181-188
• /
• 2009

본 논문은 실험단위들의 구조적 특성으로 지분관계를 갖는 실험을 행해야 하는 경우를 가정한다. 지분계획하에서 처리를 구성하는 요인으로 반복측정 요인을 고려한다. 반복측정 요인의 수준들이 비확률화에 의해 지분구조의 실험단위들에 배정될 때, 비확률화에 따른 실험의 특성을 감안한 모형으로 복합대칭의 공분산 구조하에서 혼합효과 모형을 논의하고 있다. 처리의 일부 요인들이 시간 또는 공간상의 제약으로 인해 지분구조의 실험단위들에 임의적으로 배정될 수 없을 때, 지분구조의 실험단위들에 대한 반응 값들은 어떤 구조적 상관관계를 나타내는 값들로 관측될 수 있음을 예상할 수 있다. 자료의 구조적 상관성을 고려한 공분산 구조하의 선형모형으로 확률요인과 고정요인을 포함하는 혼합효과의 모형을 제시하고 모형내 미지모수들에 대한 추론방법을 다루고 있다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권4호
• /
• pp.557-562
• /
• 2008

In this paper, experiments have been performed for the investigation of tribological characteristics of automobile gear oil with the addition of ZDDP and DEP by using the FALEX WEAR TEST MACHINE. The results are as follows. The wear characteristics of gear oil was improved by adding compound additives. The extreme pressure of gear oil increases and then decreases with the applied load. The maximum extreme pressure of gear oil with compound additive is bigger then that of pure gear oil. The friction coefficient of pure gear oil monotonically increases with the temperature, but that of gear oil mixed with the additives decreases at the high temperature.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
• /
• pp.100.4-100
• /
• 1998

• 한국염색가공학회지
• /
• 제5권1호
• /
• pp.10-18
• /
• 1993

Epoxy compound was synthesized from bisphellol-A with epichlorophydrine. Epoxy compound and siloxane were emulsified conjugative one or another. The water repellency of silk fabrics was also highly improved by the treatment of epoxy-siloxane mixed emulsions containing stannic chloride and zirconium oxychloride. The maximum wrinkle recovery was obtained from the fabrics treated under the condition 2.5%-epoxy-siloxane emulsion at 16$0^{\circ}C$. The breaking elongation, the reflectance, the tensile strength and the bending properties of silk fabrics were not degraded severely by the treatment of epoxy-siloxane emulsion.

• 한국식품영양과학회지
• /
• 제26권1호
• /
• pp.144-147
• /
• 1997

산국의 꽃으로부터 2종의 sesquiterpene lactones을 분리정제하였으며, 각각 Compound I 과 II로 명명하였으며, 이 두 물질을 Sarcoma180에 감염된 ICR mouse에 대하여 항암효과실험을 수행한 결과 Compound I과 II의 투여농도가 10mg/kg일 때 수명 연장효과가 각 각 143%, 134%로 나타났다. 또한 Compound I 과 II 를 1mg/kg 씩을 섞어서 투여하였을 때에 158%의 수명 연장효과가 나타났다