• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.4
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• pp.758-770
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• 1996

Discectomy is the oldest and most commonly performed operation for the painful temporomandibular joint with internal derangement. It is the one operation for which there are longest follow-up study, with Eriksson, Silver, and Tolvanen et al reporting good results in patients about 30 years after discectomy. About 80% to 90% of patients clinically experience relief from pain and dysfunction after discectomy, and interestingly, the results may improve with time. However such as Myrhaug found headache and Poswillo supposed pain and limitation of movement as postoperative complications, even though this operation had the longest follow-up term, several aspects of discectomy remain unclear. The controversies to discectomy for TMJ with pain and dysfunction have laid emphasis only upon clinical results, and then the histomorphological study was planned to evaluate the morphologic change of TMJ after discectomy. To clarify the nature of the change through an observation on the morphologic changes of articular cartilage and subchondral bone of the condyle resulting from experimental unilateral discectomy in rabbit, the author excised the left articular discs of 12 male rabbits(control 4 rabbits), weighing about 3kg, and at 1, 3, 6, 9 weeks following surgery, harvested both(left surgical site and right nonsurgical sits) TMJ. The specimens were examined with light microscope after H-E and MT stain and the obtained results were as follows. 1. Histopathological features showed thickening of articular zone and active proliferation of fibrocartilaginous zone associated with slight proliferative zone in surgical site than control group. Also replacement of chondrocytes in calcified cartilaginous zone into bone cells was observed. 2. There were thinning of thickness of each zone of articular cartilage except calcified cartilagnous zone was observed in nonsurgical site. 3. In MT stain of condylar trabeculae, there was increased calcification in nonsurgical site than control and surgical site and the degree of calcification was similar in surgical site and control group. 4. In both site of experimental group no features of degenerative changes were observed. From the above results, it is presumed that the morphologic changes of surgical site discectomy are compensatory remodeling process characterized by an hyperplastic reaction of the articular zone and fibrocartilaginous zone filling the void created by removing the disc, and the bone changes are secondary to changes in the cartilage. Increased degree of calcification seen in condylar trabeculae of nonsurgical site results from the excessive use of condyle of that site.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.95-95
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• 2002

Human embryonic stem (hES) cells can be induced to differentiate into tyrosine hydroxylase expressing (TH+) cells that may serve as an alternative for cell replacement therapy for Parkinson's disease (PD). To examine in vitro differentiation of hES (MB03, registered in NIH) cells into TH+ cells, hES cells were induced to differentiate according to the 4-/4+ protocol using retinoic acid (RA), ascorbic acid (AA), and/or lithium chloride (LiCl) followed by culture in N2 medium for 14 days, during which time the differentiation occurs. Immunocytochemical stainings of the cells revealed that approximately 21.1% of cells treated with RA plus AA expressed TH protein that is higher than the ratio of TH+ cells seen in any other treatment groups (RA, RA+LiCl or RA+AA+LiCl). In order to see the differentiation pattern in vivo and the ability of in vitro differentiation-induced cells in easing symptomatic motor function of PD animal model, cells (2 $\times$ 10$^{5}$ cells/2${mu}ell$) undergone 4-/4+ protocol using RA plus AA without any further treatment were transplanted into unilateral striatum of MPTP-lesioned PD animal model (C57BL/6). Following the surgery, motor behavior of the animals was examined by measuring the retention time on an accelerating rotar-rod far next 10 weeks. No significant differences in retention time of the animals were noticed until 2 weeks post-graft; however, it increased markedly at 6 weeks and 10 weeks time point after the surgery. Immunohistochemical studies confirmed that a reasonable number of TH+ cells were found at the graft site as well as other remote sites, showing the migrating nature of embryonic stem cells. These results suggest that in viかo differentiated hES cells relieve symptomatic motor behavior of PD animal model and should be considered as a promising alternative for the treatment of PD.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.566-572
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• 2020

In the recent years, thin film solar cells (TFSCs) have emerged as a viable replacement for crystalline silicon solar cells and offer a variety of choices, particularly in terms of synthesis processes and substrates (rigid or flexible, metal or insulator). Among the thin-film absorber materials, SnS has great potential for the manufacturing of low-cost TFSCs due to its suitable optical and electrical properties, non-toxic nature, and earth abundancy. However, the efficiency of SnS-based solar cells is found to be in the range of 1 ~ 4 % and remains far below those of CdTe-, CIGS-, and CZTSSe-based TFSCs. Aside from the improvement in the physical properties of absorber layer, enormous efforts have been focused on the development of suitable buffer layer for SnS-based solar cells. Herein, we investigate the device performance of SnS-based TFSCs by introducing double buffer layers, in which CdS is applied as first buffer layer and ZnMgO films is employed as second buffer layer. The effect of the composition ratio (Mg/(Mg+Zn)) of RF sputtered ZnMgO films on the device performance is studied. The structural and optical properties of ZnMgO films with various Mg/(Mg+Zn) ratios are also analyzed systemically. The fabricated SnS-based TFSCs with device structure of SLG/Mo/SnS/CdS/ZnMgO/AZO/Al exhibit a highest cell efficiency of 1.84 % along with open-circuit voltage of 0.302 V, short-circuit current density of 13.55 mA cm^-2, and fill factor of 0.45 with an optimum Mg/(Mg + Zn) ratio of 0.02.

• Journal of the Korean association of regional geographers
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• v.7 no.4
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• pp.48-64
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• 2001

In the dissertation, Bibos are discussed as landscape features in the geographical context of Youngnam Region. The bibo tradition in Youngnam Region began with the incorporation of temple structures in Shilla and Kaya kingdoms, and spread throughout the country during the period of Unified Shilla. In Korea Dynasty, the diffusion of temple Bibo gained momentum, because Buddhism was worshipped as national religion. Then came a sea change in the Bibo repertoire with the replacement of Buddhism by Confucianism as an ideological prop for Chason Korea. The retreat of Buddhism led to the popularization of feng-shui motifs in Bibo strategy. The centers of the diffusion of the logic of bibo were major towns such as Kyongju, Ahndong, Sangju, and Chinju. The diffusion process continued top-down to mid-sized towns, and to the bottom of small villages. What sustained the hierarchical diffusion of Bibo attributes was myriad of transportation lines. The main artery of the diffusion in Korea Dynasty was that connecting Kaegyong to Kyongju. That same function was performed by the royal road running from Seoul through Sangju, Milyang, and to Tongrae. In the age of modernization, the feng-shui and Bibo landscapes have lost their original aura. They have suffered from the ruthless attacks of the Enlightenment logic of science. However, the elan vital of feng-shui and Bibo are still visible and strongly felt in the countryside. From field experiences, one can notice that the Bibo landscapes are tightly integrated into the rural way of life. The durability of the traditional geomancy shows us the beauty of the harmonious interplay between Youngnam people and the nature.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.68.1-68.1
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• 2012

The best part of graphene is - charge-carriers in it are mass less particles which move in near relativistic speeds. Comparing to other materials, electrons in graphene travel much faster - at speeds of $10^8cm/s$. A graphene sheet is pure enough to ensure that electrons can travel a fair distance before colliding. Electronic devices few nanometers long that would be able to transmit charge at breath taking speeds for a fraction of power compared to present day CMOS transistors. Many researches try to check a possibility to make it a perfect replacement for silicon based devices. Graphene has shown high potential to be used as interconnects in the field of high frequency electrical devices. With all those advantages of graphene, we demonstrate characteristics of electrical and optical properties of graphene such as the effect of graphene geometry on the microwave properties using the measurements of S-parameter in range of 500 MHz - 40 GHz at room temperature condition. We confirm that impedance and resistance decrease with increasing the number of graphene layer and w/L ratio. This result shows proper geometry of graphene to be used as high frequency interconnects. This study also presents the optical properties of graphene oxide (GO), which were deposited in different substrate, or influenced by oxygen plasma, were confirmed using different characterization techniques. 4-6 layers of the polycrystalline GO layers, which were confirmed by High resolution transmission electron microscopy (HRTEM) and electron diffraction analysis, were shown short range order of crystallization by the substrate as well as interlayer effect with an increase in interplanar spacing, which can be attributed to the presence of oxygen functional groups on its layers. X-ray photoelectron Spectroscopy (XPS) and Raman spectroscopy confirms the presence of the $sp^2$ and $sp^3$ hybridization due to the disordered crystal structures of the carbon atoms results from oxidation, and Fourier Transform Infrared spectroscopy (FTIR) and XPS analysis shows the changes in oxygen functional groups with nature of substrate. Moreover, the photoluminescent (PL) peak emission wavelength varies with substrate and the broad energy level distribution produces excitation dependent PL emission in a broad wavelength ranging from 400 to 650 nm. The structural and optical properties of oxygen plasma treated GO films for possible optoelectronic applications were also investigated using various characterization techniques. HRTEM and electron diffraction analysis confirmed that the oxygen plasma treatment results short range order crystallization in GO films with an increase in interplanar spacing, which can be attributed to the presence of oxygen functional groups. In addition, Electron energy loss spectroscopy (EELS) and Raman spectroscopy confirms the presence of the $sp^2$ and $sp^3$ hybridization due to the disordered crystal structures of the carbon atoms results from oxidation and XPS analysis shows that epoxy pairs convert to more stable C=O and O-C=O groups with oxygen plasma treatment. The broad energy level distribution resulting from the broad size distribution of the $sp^2$ clusters produces excitation dependent PL emission in a broad wavelength range from 400 to 650 nm. Our results suggest that substrate influenced, or oxygen treatment GO has higher potential for future optoelectronic devices by its various optical properties and visible PL emission.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.136-143
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• 2006

In this study, recently it is urgently required that demolition waste concrete has to be recycled on the construction because urban development is accelerated and redevelopment project is rapidly expanded, production quantity of construction and demolition waste concrete is being increased. As a results of drying shrinkage test under restrained and unrestrained condition, although workability and mechanical properites of concrete using HQRS were similar to that of concrete using natural sand, there were a great difference in deformation characteristic of dry shrinkage according to replacement ratio of HQRS. And, it makes sure that use of HQRS instead of partial nature sand was effective because drying shrinkage of concrete using 30 volume percentage of HQRS was smaller than that using only natural sand. Therefore, it is the objective of this study to provide the fundamental data about the re-application as an analysis of the drying shrinkage characteristics of concrete using HQRS and it is able to creta a high value-added by using HQRS.

• Korean Journal of Materials Research
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• v.29 no.11
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• pp.727-733
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• 2019

In this study, the glass melting properties are evaluated to examine the possibility of using refused coal ore as replacement for ceramic materials. To fabricate the glass, refused coal ore with calcium carbonate and sodium carbonate in it (which are added as supplementary materials) is put into an alumina crucible, melted at $1,200{\sim}1,500^{\circ}C$ for 1 hr, and then annealed at $600^{\circ}C$ for 2 hrs. We fabricate a black colored glass. The properties of the glass are measured by XRD (X-ray diffractometry) and TG-DTA (thermogravimetry-differential thermal analysis). Glass samples manufactured at more than $1,300^{\circ}C$ with more than 60 % of refused coal ore are found by XRD to be non-crystalline in nature. In the case of the glass sample with 40 % of refused coal ore, from the sample melted at $1,200^{\circ}C$, a sodium aluminum phosphate peak, a disodium calcium silicate peak, and an unknown peak are observed. On the other hand, in the sample melted at $1,300^{\circ}C$, only the sodium aluminum phosphate peak and unknown peak are observed. And, peak changes that affect crystallization of the glass according to melting temperature are found. Therefore, it is concluded that glass with refused coal ore has good melting conditions at more than $1,200^{\circ}C$ and so can be applied to the construction field for materials such as glass tile, foamed glass panels, etc.

• Journal of Ethics
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• no.74
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• pp.35-62
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• 2009

This study purports to explore the possibility of establishing the theory of ethics education based on the concept 'Gyeong(敬)' in Early Confucianism. There was a negative viewpoint on Confucianism directly after the modernization of Korea. However, a positive trend for Confucianism has emerged in almost all sorts of studies even though the results of the studies in Moral education are not always successful. West moral education theories and traditional ethics education theories should be integrated dialectically so that traditional ethics education may be updated. Recently a reappraisal of traditional values has been undertaken as a replacement of liberal democracy values. Faced with the modern civilization's crisis and a decline in morals in Korea, reverence needs to be dealt with in ethics education. This study is primarily concerned with the nature-transcendental relation whose concrete concept is 'Gyeong(敬)' in Confucianism. And the study attempts to put forward the theory of reverence-centered ethics education. The contents of the study consists of the substance of 'Gyeong(敬)' in Early Confucianism, and practical principles and methods of reverence-based ethics education. Some tasks of moral education are also suggested for the scientific establishment of reverence-centered ethics education.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.153-170
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• 1977

Considering the ways for the possible improvement of soil test for upland crops, various methods for the evaluation of K supplying power and testing of available soil K were reviewed in terms of theoretical principles and practical usefulness of the each method. The review was also made on the characteristics of upland crops in K requirement and on the chemical properties of major korean upland and lowland rice soils in terms of K availability. Following is the few remarks drawn from the review. 1. Quite large number of methods have been known for the evaluation of K supplying power and testing for available soil K. In nature, they can be divided into two categories; capacity-based methods and intensity-based methcds. The capacity-based methods usually measure the exchangeable and some portion of nonexchangeable K, while the intensity-based methods suggest to consider the ractivity ratios of major cations in soil solution and the energy requirement for the replacement of exchangeable soil K into soil solution. 2. As methodology for extraction of interested part of soil K, chemical extraction, electrodialysis and ion exchange methods have been known. Among these, chemical extract ion is favorable because of its simplicity. However, recently suggested Electro-Ultra-Filtration method seems to merit further study for wider use for not only K but also other nutrient availability of soils. 3. The intensity-based methods, although they are more theoretical, because of their complexity, in methods may not be adapted for practical soil tests. 4. The exchangeable K which is rather simple to measure and which well reflects the status of K reserve as nonexchangeable and is immediate pool of water soluble K may be good, if not best, criterion of soil K availability to plant in common soil testing. 5. Because there are evidences that the abundance of available K alone may not be good inclication for availability of K to plant, it is recommendable to interprete the exchangeable K data as percent saturation of exchangeable K to total C. E. C. of soil for the recommend ation of K fertilizer based on soil tests. 6. Some pot and field trial results showed the trends that percent potassium saturation to total C. E. C. better serve as the parameter for K fertilizer recommendation.

• Clinical and Experimental Pediatrics
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• v.50 no.10
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• pp.976-981
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• 2007

Purpose : Aortic valve or aortic root (AoRo) replacement is occasionally required because of AoRo dilatation and aortic regurgitation (AR) in repaired tetralogy of Fallot (TOF). We evaluated AoRo size and possible factors associated with its hemodynamic nature in patients with repaired TOF. Methods : We investigated 130 repaired TOF patients more than 15 years of age who followed-up by echocardiography from January 2002 to December 2003. Of 130 patients, we identified 17 patients with AoRo dilatation, which was defined as ratio of expected AoRo size by standard nomogram (AoRo ratio) >1.5 (dilator group), and 113 TOF controls, with AoRo ratio <1.5 (non-dilator group). Results : Mean indexed AoRo size ($mm/m^2$) in the first echo was $24{\pm}3.2$ in the dilator group and $18{\pm}3.4$ in the non-dilator group (P<0.0001). AoRo rate of change (mm/year) from the first to latest echo study was $1.6{\pm}3.8$ in dilator group and $0.05{\pm}1.6$ in the non dilator group (P=0.0021). Patients from the dilator group showed a higher prevalence of pulmonary atresia (P=0.031) and a history of aortopulmonary shunt before repair (P=0.048), moderate to severe AR (P=0.0065), and increased left ventricular end-diastolic dimensions (P=0.003). Conclusions : A subset of patients late after TOF repair may show progressive dilatation of AoRo. To identify and prevent long-term sequelae in this patient group, regular follow-up and speculation about AoRo after TOF repair is recommended.