• Restorative Dentistry and Endodontics
• /
• v.9 no.1
• /
• pp.101-106
• /
• 1983

It was the purpose of this study to investigate the fracture mode of dental amalgam by observing the crack propagation, and to relate this to the microstructure of the amalgam. Caulk 20th Century Regular, Caulk Spherical, Dispersalloy, and Tytin amalgam alloys were used for this study. After each amalgam alloy and Hg measured exactly by the balance was triturated by the mechanical amalgamator (Capmaster, S.S. White), the triturated mass was inserted into the cylindrical metal mold which was 4 mm in diameter and 12 mm in height and was pressed by the Instron Universal Testing Machine at the speed of 1mm/min with 120Kg. The specimen removed from the mold was stored in the room temperature for a week. This specimen was polished with the emery papers from #100 to #200 and finally on the polishing cloth with 0.06${\mu}Al_2O_3$ powder suspended in water. The specimen was placed on the Instron testing machine in the method similar to the diametral tensile test and loaded at the crosshead speed of 0.05mm/min. The load was stopped short of fracture. The cracks on the polished surface of specimen was examined with scanning electron microscope (JSM-35) and analyzed by EPMA (Electron probe microanalyzer). The following results were obtained. 1. In low copper lathe-cut amalgam, the crack went through the voids and ${\gamma}_2$ phase, through the ${\gamma}_1$ phase around the ${\gamma}$ particles. 2. In low copper spherical amalgam, it was observed that the crack passed through the ${\gamma}_2$ and ${\gamma}_1$ phase, and through the boundary between the ${\gamma}_1$ and ${\gamma}$ phase. 3. In high copper dispersant (Dispersalloy) amalgam, the crack was found to propagate at the interface between the ${\gamma}_1$ matrix and reaction ring around the dispersant (Ag-Cu) particles, and to pass through the Ag-Sn particles. 4. In high copper single composition (Tytin) amalgam, the crack went through the ${\gamma}_1$ matrix between ${\eta}$ crystals, and through the unreacted alloy particle (core).

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.11a
• /
• pp.135-135
• /
• 2003

The fast evolution in the fold of optical communication systems demands powerful optical information treatment. These functions can be performed by integrated optical systems. A key component of such systems is erbium doped waveguide amplifier(EDWA). The intra 4f radiative transition of Er at 1.5 $\mu\textrm{m}$ is particularly interesting because this wavelength is standard in optical telecommunications. The fabrication of waveguide amplifier for integrated optics using sol-gel process has received an increasing attention. Potential advantage of lower cost by less capital equipment and easy processing makes this process an attractive alternatives to conventional technologies like flame hydrolysis deposition, ion exchange and chemical vapor deposition, etc. In addition, sol-gel process has been found to be extremely suitable for the control of composition and refractive index related directly with optical properties. The main drawback of such an amplifier with respect to the EDWA is the need for a much higher Er3+ concentration to compensate for the smaller interaction length. However, the high doping of Er might be resulted in the non-radiative relaxation by clustering of Er ions End co-operative upconversion. In order to solve this problem, we investigate the possibility of avoiding short Er-Er distances by encapsulation of Er3+ ions in hosts such as organic-inorganic hybrid materials. For inorganic-organic hybrid sols, methacryloxypropyltrimethoxysilane (MPTS), zirconyl chloride octahydrate and erbium(III) chloride hexahydrate were used as starting materials, followed by conventional sol-gel process. It was observed by TEM that nano sols having core/shell toplology were formed, depending on the mole ratio of Zr/Er. The surface roughness for the coatings on Si substrate was investigated by AFM as a function of Zr/Er ratio. The local environment and vibrational Properties of Er3+ ions were studied using Near-IR, FT-IR, and UV/Vis spectroscopy. Nano hybrid coatings derived from polymer and Er doped encapsulation Eave the good luminescence at 1.55$\mu\textrm{m}$.

• Korean Journal of Oriental Medicine
• /
• v.18 no.2
• /
• pp.17-24
• /
• 2012

Research on Seokgok(石谷), Lee Gyu Jun(李圭晙, 1855~1923)'s thought and medicine was progressed from various angles. There is no research on Chinese poem(漢詩) accounting for the half of his collection of literary works, "Seokgoksango(石谷散稿)" yet. Hence, the article reviewed concerns on his life and what life he lived as a Confusion(儒家) writer through his Chinese poem. Should read "Seokgoksango", Seokgok's spiritual orientation and attitude to life were found to have its core in the Confusion(儒家的), especially ethical(道學的) aspect. Seokgok's Chinese poem materialized his spiritual composition more, able to access up to general emotional state, representing concerns and frustration of intellectuals in the latter era of the Choson Dynasty. Anxiety consciousness(憂患) of patriotism and love of the people which traditional intellectuals implicated enough at the turbulent era of early modern time appeared strongly in his works. Also works seeking for devotion(歸依) toward the clean world(淸明世界) staring at the corrupt world losing the national sovereignty at the same time and the expansion(擴散) was able to be found many. The latter half of the 19th century and the early 20th century when Seokgok lived was the period of changeover in the history of civilization called intersection between traditional era and modern times. His Chinese poem showed traditional intellectuals' anxiety, frustration, conflict, and hope based on such times. Along with the status of an Oriental, medical doctor and thinker, up to discussion on the quality of a writer, the intensified research on him is expected.

• Korean Institute of Interior Design Journal
• /
• v.23 no.3
• /
• pp.56-63
• /
• 2014

Furniture has been developed in pursuit of human convenience and comfort, but nowadays it does not consider human users and gradually loses the essence of furniture. Especially furniture design that disregards the relation with space loses both the meaning and purpose of furniture. In this regards, it is necessary to understand the essence of furniture design and establish a design direction for future progress. Based on the relation between furniture and space, this paper intended to study on John Pawson's works that pursued the essence of design focusing on users, and propose a direction in a sense of real meaning for modern furniture design after exploring the characteristic of the furniture design of John Pawson. The study method of this paper was to investigate the design language of John Pawson and analyze his furniture in the morphological structural, functional, and material aspects. Based on such analysis, this study investigated the characteristics of the furniture design and found out what the core of the design that he pursued was. The scope of the study included the Independent Furniture that was restricted furniture collections of Driade and Spatial Furniture designed and installed at the stage of space construction. The study result showed that the design of John Pawson considered 'the suitability to a specific place' as important factor and furniture was planned at the stage of planning space. Each independent furniture defines all spaces in the morphological, lay-out and functional aspects of furniture and emphasizes their own property. As Spatial Furniture shares the function of spatial composition element, Pawson's furniture can be all called Spatial Furniture.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.2
• /
• pp.280-286
• /
• 2020

Cards made from PVC and PET materials do not oxidize or decompose readily, so they are generally incinerated or landfilled after use and cause pollution problems, such as environmental hormones and combustion gases during incineration. In addition, there is a problem of environmental pollution because they are discarded as semi-permanent refuse without being decomposed at landfill. This study attempted to solve this problem using polylactic acid (PLA), which is a representative biodegradable material as a substitute material that can solve the issues with these cards. On the other hand, when the thin card core sheet is made from only PLA material, the physical properties of the material are insufficient, such as the low temperature impact strength, high temperature stability, and poor bending properties, so its use is limited. To solve this problem, the compositional ratio of PLA was reviewed, and the optimal biodegradable compound composition was determined through an examination of the compositions, such as crystallization nucleating agents, additives, and nano compound technology. The high functionalization as a biodegradable card was verified through a laminating process using annealing technology.

• Journal of Distribution Science
• /
• v.17 no.6
• /
• pp.5-13
• /
• 2019

Purpose - The potential for small businesses in the distribution sector to contribute to socio-economic development remains largely inert due to a litany of challenges that they face. Incubators have emerged as the 'silver bullet' for most of the problems but the extent to which they are effectively helping small business overcome their challenges remains debatable. This study seeks to determine the core reasons why respondents enrolled in an incubator, the essence of the incubator and the extent to which the incubator performance is satisfactory. Research design, data, and methodology - A positivist philosophical approach was adopted for the study. This quantitative study used a survey method to collect data from incubatees in a cross-sectional manner. The data were subsequently analysed to generate necessary insights. Results - Results reveal that the gender composition of incubatees is severely skewed in favour of males. Also, most incubatees enrolled in the incubators with a hope that it would ease their pathway to big businesses, financiers and business registration institutions, and it is not. Conclusion - Incubators are mostly inward-looking and are adept at offering training interventions. To improve the effectiveness of incubators, it is necessary to invest efforts in attracting more females and building networks with key external stakeholders that could possibly assist the incubatees establish and grow their businesses.

• Journal of Nutrition and Health
• /
• v.36 no.8
• /
• pp.870-881
• /
• 2003

We examined the effects of 5 g red pepper powder in soup preload given at breakfast on food intake, blood pressure, body core temperature, hunger, fullness and thirst scores in 29 female collage students. All subjects received two kind of soup preloads in random order. After ingesting a soup, subjects ate other food items as a breakfast ad libitum. Two soups were of the same composition and volume but differed only in 5 g red pepper. So one soup designated as "beef-vegetable" and the other soup designated as "red pepper". Red pepper soup consumption significantly enhanced energy and macronutrient intake by 17%. The hunger scores after test meals were inversely correlated with energy and nutrient intake in beef-vegetable meal. However, the postprandial hunger scores were not correlated with energy and nutrient intakes in red pepper meal. The fullness scores at 90 min after the red pepper meal were inversely correlated with energy and nutrient intake whereas the fullness scores after beef-vegetable meal were not correlated with energy and nutrient intake. These results suggest that hot red pepper ingestion may desensitize some gastrointestinal vagal afferents and disturb feeling of hunger and fullness. The postprandial changes of body temperatures in red pepper meal were higher for a longer time in comparison with those in beef-vegetable meal. For the red pepper meal there frequently were higher correlations between blood pressures and anthropometric measurements, compared to those in beef-vegetable meal. These results might be explained partly by the enhancing effects of capsaicin on thermogenesis and sympathetic nervous system activity. It is concluded that the ingestion of spicy soup with red pepper can increase appetite, energy and nutrient intakes in Korean females, and this effect might be related to disturbed feeling of hunger and fullness.hunger and fullness.

• Asian-Australasian Journal of Animal Sciences
• /
• v.30 no.4
• /
• pp.531-537
• /
• 2017

Objective: This experiment was conducted to explore the impact of diet on the ruminal microbial community in goats. Methods: Twelve goats were divided into two groups and fed complete feed (CF) or all forage (AF) diet. The total microbial DNAs in the rumen liquid were extracted. The V4 region of microbial 16S rRNA genes was amplified and sequenced using high-throughput. Information of sequences was mainly analyzed by QIIME 1.8.0. Results: The results showed that Bacteroidetes and Firmicutes were the most predominant microbial phyla in the rumen of all goats. At genus level, the abundance of fiber-digesting bacteria such as Ruminococcus and Lachnospiracea incertae sedis was significantly higher in AF than that in CF, while the levels of fat-degrading bacterium Anaerovibrio and protein-degrading bacterium Pseudomonas were opposite. The core shared genera, Prevotella and Butyrivibrio were widespread in the rumen of goats and no significant difference was observed in relative abundance between groups. Conclusion: We concluded that the richness of fiber-, protein-, and fat-digesting bacteria was affected by diet and tended to increase with the rise of their corresponding substrate contents in the ration; some bacteria shared by all goats maintained stable despite the difference in the ration, and they might be essential in maintaining the normal function of rumen.

• Proceedings of the Korea Contents Association Conference
• /
• 2009.05a
• /
• pp.770-775
• /
• 2009

Along with the advance of USN technology in a human-oriented informatization society these days, society is quickly changing into a ubiquitous computing society in which information even between objects can be organically combined and utilized. In order to successfully build such a ubiquitous computing society, it is indispensable to have core USN technologies such as USN sensor nodes, sensor networks, USN middleware, and USN applied services that efficiently manage sensing information collected from sensor nodes, and support the abstraction function for the composition of sensor networks. In order to process the transmission event of sensing values that are generated from various USN terminal devices, this study designs a process that performs the abstraction of data for the efficient process of diverse sensing values transferred from USN and RFID terminal devices.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.40 no.1
• /
• pp.11-21
• /
• 2017

Artillery fire power due to effectiveness which is hard to predict well-planned and surprising attack can give a fear and shock to the personnel and is a very core weapon system and takes a critical role in wartime. Therefore in order to maximize operational effectiveness, Army required protecting artillery and takes a quick attack action through rapid construction of artillery's positions. The artillery use artillery's position to prevent exposure by moving to other position frequently. They have to move and construct at new artillery's positions quickly against exposing existed place by foe's recognition. These positions should be built by not manpower but engineering construction equipment. Because artillery positions have to protect human and artillery equipment well and build quickly. Military engineering battalion have lots of construction equipment which include excavator, loader, dozer, combat multi-purposed excavator, armored combat earthmover dump truck and so on. So they have to decide to optimal number of Team combining these equipments and determine construction sequence of artillery's position in operational plan. In this research, we propose to decide number of Team efficiently and allocate required construction's positions for each Team under constraints of limited equipments and time. To do so, we develop efficient heuristic method which can give near optimal solution and be applied to various situation including commander's intention, artillery position's priority or grouping etc. This heuristic can support quick and flexible construction plan of artillery positions not only for using various composition's equipment to organize Teams but also for changing quantity of positions.