• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.104-109
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• 2016

In Korea, the government has invested the installation of artificial reefs (ARs) which deploying to enhance the restoration of marine environment and productivity on the coastal area at the part of 222,627ha, from 1971 to 2014 for 44 years. The number of ARs are gradually increasing, while their comparison and corelation analysis were not much studied. Therefore, this study is to analyse temporal variation of ARs which composed of concrete named the Horn triangle reefs were deployed at Pohang, Jangkil-ri, a depth of 5 to 7m, in 2003, was monitored 4 times from 2009 to 2011. In results, the biodiversity investigated that the dominant species was Mollusca Omphalius pfeifferi except in 2009. The different species mainly depend on spatial-temporal variation. In this type of study can be used to the R&D, management and government policy of ARs as well improving marine environment.

• Journal of the Korean Solar Energy Society
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• v.37 no.1
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• pp.47-57
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• 2017

Solar energy is one of the important renewable energy resources. It can be used for air heating, hot water supply, heat source of desiccant cooling system and so on. And many researches for enhancing efficiency have been conducted because of these various uses of solar thermal energy. This study was performed to investigate the air heating performance of hybrid solar air-water heater that can heat air and liquid respectively or simultaneously and finding method for improving thermal performance of this collector. This collector has both liquid pipe and air channel different with the traditional solar water and air heater. Fins were installed in the air channel for enhancing the air heating performance of collector. Also air inlet & outlet temperature, ambient temperature and solar collector's inner part temperature were confirmed with different air velocity on similar solar irradiance. As a result, temperature of heated air was shown about $43^{\circ}C$ to $60^{\circ}C$ on the $30^{\circ}C$ of ambient temperature and thermal efficiency of solar collector was shown 28% to 73% with respect to air velocity. Also, possibility of improvement of thermal performance of this collector could be ascertained from the heat transfer coefficient calculated from this experiment. Thus, it is considered that the research for finding optimal structure of hybrid solar air-water heater for enhancing thermal performance might be needed to conduct as further study based on the method for improving air heating performance confirmed in this study.

• Journal of Korean Society of Forest Science
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• v.96 no.5
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• pp.520-527
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• 2007

Biomass and species diversity of understory vegetation after fertilization were studied for 28-year-old Quercus acutissima plantation (MQA), 29-year-old Pinus densiflora plantation (MPD), 8-year-old Betula platyphylla var. japonica plantation after coal reclamation (YBP), and 4-year-old Pinus densiflora plantation after forest fire (YPD) in central Korea. Nitrogen + phosphorus + potassium (6:4:1) fertilizer was applied for 3 years from 2004. Thereafter photosynthetically active radiation (PAR) and understory species richness and diversity were measured in late July-early August 2006. PAR (${\mu}mol\;m^{-2}S^{-1}$) was higher at the fertilization treatment (100.9) than at the control (67.0) for MQA while was lower at the fertilization treatment (156.5) than at the control (268.7) for MPD. Total understory biomass (t $ha^{-1}$) was lower at the fertilization plot (1.8) than at the control plot (3.0) for YPD, however, there were no differences in biomass between fertilization and control plots for MQA, MPD and YBP. Total species number of understory vegetation was higher for fertilization than for control at MPD (47 vs. 45) and YPD (21 vs. 13), and was higher for mature plantations (33 vs. 37 for MQA and 47 vs. 45 for MPD) than for young plantations (16 vs. 16 for YBP and 21 vs. 13 for YPD). Species richness and diversity were higher at the fertilization treatment than at the control for MQA, YBP, and YPD while were lower at the fertilization treatment than at the control for MPD, however, the differences were not statistically significant. Our results indicate that there were no consistent patterns in light conditions, biomass and species richness and diversity of understory vegetation following fertilization. More detailed long-term studies with different fertilizer applications would be necessary to conclude the influence of fertilization on understory vegetation in the region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.75-75
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• 2009

반도체 및 전자기기 산업에 있어 비활성메모리 (NVM)는 중요한 부운을 차지한다. NVM은 디스플레이 분야에 많은 기여를 하고 있으며, 특히 AMOLED에 적용이 가능하여 온도에 따라 변하는 구동 전류, 휘도, color balance에 따른 문제를 해결하는데 큰 역할을 한다. 본 연구는 NNN 구조에서 터널 층을 $SiN_X$ 박막에서 $SiO_XN_Y$ 박막으로 대체하기위한 $SiO_XN_Y$ 박막을 이용한 NNO구조의 NVM에 관한 연구이다. 이로 인하여 보다 얇으면서 우수한 절연 특성을 가지는 박막을 사용함으로써 실리콘 층으로부터 전하의 터널링 효과를 높여 전하 저장 정도를 높이고, 메모리 retention 특성을 향상시키는 터널 박막을 성장 시킬 수 있다. 최적의 NNO 구조의 메모리 소자를 제작하기 위하여 MIS 상태로 다양한 조건의 실험을 진행하였다. 처음으로 블로킹 박막의 두께를 조절하는 실험을 진행하여 최적 두께의 블로킹 박막을 찾았으며, 다음으로 전하 저장 박막의 band gap을 조절하여 최적의 band gap을 갖는 $SiN_X$ 박막을 찾았다. 마지막으로 최적두께의 $SiO_XN_Y$박막을 찾는 실험을 진행하였다. MIS 상태에서의 최적의 NNO 구조를 이용하여 유리 기판 상에 NNO 구조의 NVM 소자를 제작하였다. 제작된 메모리 소자는 문턱전압이 -1.48 V로 낮은 구동전압을 보였으며, I-V의 slope 값 역시 약 0.3 V/decade로 낮은 값을 보인다. 전류 점멸비($I_{ON}/I_{OFF}$)는 약 $5\times10^6$로 무수하였다. $SiN_X$의 band gap을 다양하게 조절하여 band gap 차이에 의한 밴드 저장 방식을 사용하였다. 또한 $SiN_X$은 전하를 전하 포획(trap) 방식으로 저장하기 때문에 본 연구에서의 메모리 소자는 밴드 저장 방식과 전하 포획 방식을 동시에 사용하여 우수한 메모리 특성을 갖게 될 것으로 기대된다. 우수한 비휘발성 메모리 소자를 제작하기 위해 메모리 특성에 많은 영향을 주는 터널 박막과 전하 저장 층을 다양화하여 소자를 제작하였다. 터널 박막은 터널링이 일어나기 쉽도록 최대한 얇으며, 전하 저장 층으로부터 기판으로 전하가 쉽게 빠져나오지 못하도록 절연 특성이 우수한 박막을 사용하였다. 전하 저장 층은 band gap이 작으며 trap 공간이 많은 박막을 사용하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.508-517
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• 2004

We described a near-field scanning microwave microscope which uses a high-quality dielectric resonator with a tunable screw. The operating frequency is f=4.5 5GHz. The probe tip is mounted in a cylindrical resonant cavity coupled to a dielectric resonator We developed a hybrid tip combining a reduced length of the tapered part with a small apex. In order to understand the function of the probe, we fabricated three different tips using a conventional chemical etching technique and observed three different NSMM images for patterened Cr films on glass substrates. We measured the reflection coefficient of different metal thin film samples with the same thickness of 300m and compared with theoretical impedance respectly. By tuning the tunable screw coming through the top cover, we could improve sensitivity, signal-to-noise ratio, and spatial resolution to better than $1{\mu}m$. To demonstrate the ability of local microwave characterization, the surface resistance of metallic thin films has been mapped.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.65-71
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• 2008

This paper proposes a structure of haptic collaboration system over high resolution tiled-display, and proposes a QoE (quality of experience) increase scheme in integrated system. Both haptic system and tiled-display system have requirements of computational power. A haptic device is unstable if haptic rendering rate is less than 1kHz, A requirement of tiled-display systeme is frame rate of display. It requires update of 30 frame fer sec. If we use these systems independently, we can satisfy each requirements. However, if we integrate two systems, performance of entire system significantly decreases because of lack of resources, and QoE of users also decrease. In this paper, therefore, we propose a QoE guaranty scheme which selectively allocates cpu resource between display update and haptic rendering. In order to increase QoE, we set a priority for visual and haptic in order to allocate more resource on visual or haptic. If a user sensitive about touch, then proposed scheme increases haptic rendering rate by allocating more resource. Otherwise a user more sensitive about visual than haptic, proposed scheme decreases haptic rendering rate and increases tiled-display update rate. Therefore, by selectively allocating limited cpu resource, proposed scheme guaranties QoE of both haptic and visual.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.275-280
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• 2009

Radicular cyst is a true epithelium lined cyst formed when epithelium at the apex of a nonvital tooth is stimulated by inflammation. It is the most common type of cyst in the oral cavity, but its frequency is low in the primary dentition. Treatment of large-sized cyst aims at conservation of adjacent structure and allowance of proper eruption of the successive permanent teeth in the primary dentition. Considering these two aspects, marsupialization or enucleation following decompression is recommended as a treatment means for large-sized radicular cyst. In this case, 8-year old boy visited the pediatric dentistry department. Yonsei University Dental Hospital, with the chief complaint of pain on the lower right area. Clinical and radiographic examinations revealed periapical radiolucent lesion on #84, which had previous pulp treatment and restorated with the stainless steel crown. Dislocation of its successive tooth, #44, was also observed. #84 was extracted and sent for biopsy. Through histologic examination, it was diagnosed as radicular cyst. Following its extraction, removable space maintainer was delivered, which was also used as a decompressor. During periodic check-up for next 22 months, favorable healing of the lesion and eruption of the successive tooth were observed.

• Journal of The Korean Association For Science Education
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• v.33 no.1
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• pp.208-227
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• 2013

The purpose of this study is to analyze secondary science teachers' planning process for an integrated science lesson. For this study, relevant references were collected from various sources, including literatures, previous studies regarding integrated science education, and individual studies. Two teachers (one from middle school and the other from high school) participated and 'the five-step instructional design' was adopted from former studies in this subject. The teachers were asked to develop an instructional plan based on 'the design' provided. While the consultation provided a framework for an instructional plan, the teachers were asked to take a leading role in terms of selecting the chapter to be taught; analyzing the course structure; and making detailed teaching plans. In the course of consultations, discussions, records, and analysis were organized into a journal. Based on the journal, the aspects of the planning process, including difficulties and problems faced by teachers, were analyzed in-depth. From the study, it could be observed that both high school and middle school teachers face various difficulties in preparing for the integrated science lesson. Among other things, the teachers emphasized the difficulties in the stages of selecting the topic, collecting the relevant information, and restructuring and organizing the lecture contents.

• The Journal of Korean Academic Society of Nursing Education
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• v.3 no.2
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• pp.125-149
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• 1997

The role of nurses in Korea is undergoing significant change because of the economic development, medical insurance and the change of family structure. It will be predicted that the nurse's role is extended more and more in the 21C. So the nursing curriculum in nursing education is the most important thing to prepare a good quality of nursing. Furthermore qualified curriculum calls for the development of desirable attitudes in nursing students. The purpose of this descriptive study was to collect data which can be used to facilitate the process of encouraging every college to assume greater responsibility for needed curriculum and educational conditions related to preperation of nursing students for various developed society toward 21C. A total sixty one nursing college were surveyed by mail during August and October 1997. Thirty six college(59%) responded. The data was analyzed by using SAS program. The results are as follows : 1) 32 college(88.9%) answered that they have Nursing educational philosophy and goal. 2) Total credits are 136credits, and the students who don't have teacher's course need 128 credits. 3) Nursing essential subjects comprise 84 credits, and nursing clinical practice subjects are 19 credits. 4) 15 colleges(41.7%) have their own hospital for student's clinical practice, 36 college(100%) take the community nursing practice in public health center, 34college(94.4%) take the school health nursing practice. 5 college(13.9%) have industrial nursing practice. 5) 3-year nursing college have 6.4 professor, 3.5 assistent professor, 1.9 and 3.4 full faculty and 7.4 part time faculty. We sugest that 3-year college have to have nursing educational philosophy and goal in terms of nursing educational standard. To improve the quality of nursing education every college should try to increase the number of professor and to contact qualified hospital for students clinical practice.

• Journal of the Korean Electrochemical Society
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• v.15 no.2
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• pp.95-100
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• 2012

$LiFePO_4$ is an attractive cathode material due to its low cost, good cyclability and safety. But it has low ionic conductivity and working voltage impose a limitation on its application for commercial products. In order to solve these problems, the iron($Fe^{2+}$)site in $LiFePO_4$ can be substituted with other transition metal ions such as $Mn^{2+}$ in pursuance of increase the working voltage. Also, reducing the size of electrode materials to nanometer scale can improve the power density because of a larger electrode-electrolyte contact area and shorter diffusion lengths for Li ions in crystals. Therefore, we chose electrospinning as a general method to prepare $Li[Fe_{0.9}Mn_{0.1}]PO_4$ to increase the surface area. Also, there have been very a few reports on the synthesis of cathode materials by electrospinning method for Lithium ion batteries. The morphology and nanostructure of the obtained $Li[Fe_{0.9}Mn_{0.1}]PO_4$ nanofibers were characterized using scanning electron microscopy(SEM). X-ray diffraction(XRD) measurements were also carried out in order to determine the structure of $Li[Fe_{0.9}Mn_{0.1}]PO_4$ nanofibers. Electrochemical properties of $Li[Fe_{0.9}Mn_{0.1}]PO_4$ were investigated with charge/discharge measurements, electrochemical impedance spectroscopy measurements(EIS).