• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2008년도 Asian Magnetics Conference
• /
• pp.136.2-136.2
• /
• 2008

• 한국재료학회지
• /
• 제24권9호
• /
• pp.502-507
• /
• 2014

Recently, improvement in the conversion efficiency of silicon-based solar cells has been achieved by decreasing emitter doping concentration, because the lightly doped emitter can effectively prevent the recombination of electrons and holes generated by solar light irradiation. This type of emitter is very thin due to the low doping concentration, thus conductive materials (i.e., silver) used for front electrodes can easily penetrate the emitter during a firing process because of their large diffusivity in silicon. This results in junction leakage currents which might reduce cell efficiencies. In this study, $Al_2O_3$-coated Ag powders were synthesized by an ultrasonic spray pyrolysis method and applied to the conductive materials of the front electrode to control the junction leakage current. The $Al_2O_3$ shell obstructs the Ag diffusion into the emitter during the firing process. The powder is spherical with a core-shell structure and the thickness of the $Al_2O_3$ shell is tens of nanometers. Solar cells were fabricated using pure Ag powders or the $Al_2O_3$-coated Ag powder as front electrode materials, and the conversion efficiency and junction leakage current were compared to investigate the role of the $Al_2O_3$ shell during the firing processes.

• 한국실내디자인학회논문집
• /
• 제15권5호
• /
• pp.120-129
• /
• 2006

Apartments have become the most popular type of residential building in Korea since the 1960s. The dwelling space should be designed to accomodate various life styles or changing needs of family members. This research is conducted to analyze flexible interior space types of apartments and to improve the architectural planning and design of apartments that can satisfy various needs of residents. In this study, apartments of 10 - 90 pyeongs built in the region of Seoul, between 1998 and 2007, are investigated in terms of the unit plan, the number of open sides, and a distribution of flexible apartment types for each year, Apartments with flexible space are classified into 10 different types, including a flexible type between bedrooms, a flexible type between a bedroom and the livingroom, and a flexible type between the dinning room and the livingroom. According to the composition of unit plans, apartments are also differentiated as a single-corridor type, a double-corridor type, a stairway type, a hall type, and a combination type. According to these classifications, the characteristics of desirable unit plans were analyzed. The results of the analysis showed that, as the unit size of apartments get bigger, the ratio of width/depth of the front side unit plan is increased. This result reflects a trend of high-rise apartments which have an increased number of front-side bays and a shorter depth for better penetration of daylight. In addition, a hall type is found to have a wider front side and shorter depth. According to open sides, a flexible type of the livingroom and the dinning room/kitchen (L-D.K) is found to be most common for the front/back open space, and the livingroom is usually placed on the front/side open space. To meet the changing needs of residents, more research should be conducted on flexible dwelling space.

• 한국항해항만학회지
• /
• 제32권5호
• /
• pp.341-347
• /
• 2008

수변이나 연안에서의 식생은 어류의 산란지, 파랑으로부터 배후공간을 보호하고 수변의 침식을 감소하며 아름다운 자연 경관을 제공하고 있으며 수질 정화, 생태학적으로도 주요한 기능을 하고 있는 등 최근 식생의 가치가 재인식되고 있다. 그러나 수변식생에 의한 파랑변형 특성에 관한 수치적 및 이론적 연구뿐 만 아니라 해안수리학적 연구가 아직은 미흡한 상태이다. 본 연구에서는 수변식생에 의한 파랑 감쇠 특성을 비정상완경사방정식에 의한 수치모형에 의해 검토하였으며 단순한 선형장파 이론에 의한 이론적 연구 결과와 비교 검토하였다. 식생이 있는 수로에 파랑이 전파하는 경우 파랑의 감쇠특성은 지형이나 입사파 조건 뿐 만 아니라 식생조건에 따라 변화하므로 이들을 고려하여 검토하였다. 이론적 해석과 수치실험 결과를 통해 식생특성과 파랑조건 및 운동량교환 계수와 같은 파라메타의 특성을 명확히 하였다.

• 한국환경과학회지
• /
• 제20권9호
• /
• pp.1141-1149
• /
• 2011

The three-dimensional hydrodynamic model was simulated to understand coastal sea front of formation and seasonal variation in the Southern Sea of Korea. In this study, we used to concept of stratification factor, to realize seasonal distribution of stratification coefficient which of seasonal residual flow, considered with, tide, wind and density effect. Tidal current tends to flow westward during the flood and eastward during ebb. The current by the wind stress showed to be much stronger the coastal than the offshore area in the surface layer. And the current by the horizontal gradient of water density showed to be relatively weak in the coastal area, with little seasonal differences. On the other hand, the flow in the offshore area showed results similar to that of the Tsushima Warm Current. The stratification factor (SHv) was calculated by taking into account the total flow of tide, wind and density effect. In summer, the calculated SHv distribution ranged from 2.0 to 2.5, similar to that of the coastal sea front. The horizontal temperature gradient showed to be strong during the winter, when the vertical stratification is weak. On the other hand, the horizontal gradient became weak in summer, during which vertical stratification is strong. Therefore, it is presume that the strength of vertical stratification and the horizontal temperature gradient affect the position of the coastal sea front.

• 한국지구과학회지
• /
• 제33권5호
• /
• pp.377-394
• /
• 2012

To elucidate the mechanism associated with the development of heavy precipitation system, a field experiment was carried out in Jejudo (or Jeju Island) and Marado, Korea from 22 June to 12 July 2006. The synoptic atmospheric conditions were analyzed using the National Centers for Environmental Prediction-National Center for Atmospheric Research's (NCEP/NCAR) reanalyzed data, weather maps, and sounding data. The kinematic characteristics of each precipitation system were investigated by dual Doppler radar analysis. During the field experiment, data of four precipitation events with more than 20 mm rainfall were collected. In F case (frontal precipitation), a typical Changma front was dominant and the observation field was fully saturated. However there was no convective instability near the surface. LF case (low pressure accompanied with Changma front) showed strong convective instability near the surface, while a strong convergence corresponded to the low pressure from China accompanied with Changma front. In FT case (Changma front indirectly influenced by typhoon), the presence of a convective instability indicated the transport of near surface, strong additional moisture from the typhoon 'EWINIAR'. The convergence wind field was ground to be located at a low level. The convective instability was not significant in T case (precipitation of the typhoon 'EWINIAR'), since the typhoon passed through Jejudo and the Changma front was disappeared toward the northeastern region of the Korean peninsula. The kinematic (convergence and divergence) characteristics of wind fields, convective instability, and additional moisture inflow played important roles in the formation and development of heavy precipitation.

• 한국재료학회지
• /
• 제28권1호
• /
• pp.38-42
• /
• 2018

Continuous efforts are being made to improve the efficiency of Si solar cells, which is the prevailing technology at this time. As opposed to the standard front-lit solar cell design, the back-lit design suffers no shading loss because all the metal electrodes are placed on one side close to the pn junction, which is referred to as the front side, and the incoming light enters the denuded back side. In this study, a systematic comparison between the two designs was conducted by means of computer simulation. Medici, a two-dimensional semiconductor device simulation tool, was utilized for this purpose. The $0.6{\mu}m$ wavelength, the peak value for the AM-1.5 illumination, was chosen for the incident photons, and the minority-carrier recombination lifetime (${\tau}$), a key indicator of the Si substrate quality, was the main variable in the simulation on a p-type $150{\mu}m$ thick Si substrate. Qualitatively, minority-carrier recombination affected the short circuit current (Isc) but not the opencircuit voltage (Voc). The latter was most affected by series resistance associated with the electrode locations. Quantitatively, when ${\tau}{\leq}500{\mu}s$, the simulation yielded the solar cell power outputs of $20.7mW{\cdot}cm^{-2}$ and $18.6mW{\cdot}cm^{-2}$, respectively, for the front-lit and back-lit cells, a reasonable 10 % difference. However, when ${\tau}$ < $500{\mu}s$, the difference was 20 % or more, making the back-lit design less than competitive. We concluded that the back-lit design, despite its inherent benefits, is not suitable for a broad range of Si solar cells but may only be applicable in the high-end cells where float-zone (FZ) or magnetic Czochralski (MCZ) Si crystals of the highest quality are used as the substrate.

• 건축역사연구
• /
• 제25권6호
• /
• pp.17-25
• /
• 2016

Simgok Seowon is the commemorative shrine and academy established for scholar Jo Gwangjo (pen name : Jeongam). The shrine (sangnyangsik) and the east and west dormitories (Dongjae and Seojae) were built in 1636. The lecture hall, Imsimnu Pavilion, Sananggak and Munhyanggak buildings were built successively. Simgok Seowon is the only one that survived through the abolishment of seowon ordered by Regent Heungseon in the 19th century. The original seowon was renowned as a representative example showing the typical lecture hall in front and dormitory at the back (jeondanghujae) layout of the Giho School built in 1650. Two archaeological excavations were conducted in the lecture hall courtyard in 2004 and 2007~2008, which prompted debates the position of the dormitories in respect to the lecture hall, whether the dormitories should be placed in front, or at the back of the lecture hall. Simgok Seowon had been long known as a representative example of the lecture hall in front layout, but the excavations revealed contrasting evidence, suggesting the possibility for a dormitories in front layout. Recent studies and evidence show that the architecture of Simgok Seowon can be grouped into three phases. The first phase was when the shrine and both dormitories were built to the rear of the lecture hall, the second phase was when the lecture hall, Imsimnu Pavilion, Sananggak and Munhyanggak buildings were built, and lastly the third phase when the east, west dormitories were reconstructed in front of the lecture hall. The large scale construction of Simgok Seowon is related to the education based management of the academy by Doam Yi Jae, and the 17~18th century remains confirmed from the archaeological excavations are evidence of this. Remains for Imsimnu Pavilion, Sananggak, and Munhyanggak buildings have yet to be confirmed, and spaces to the south and east of the seowon are unidentified. Therefore, it is necessary to conduct investigations and research for the unexcavated spaces of the seowon, to conduct in-depth studies and for the effective adaptive re-use of the seowon.

• Journal of the korean society of oceanography
• /
• 제37권4호
• /
• pp.212-223
• /
• 2002

Cochlodinium polykrikoides bloom in 1995 was studied with a focus on an unusual coastal environment in the South Sea of Korea. Data on temperature, salinity, and zooplankton biomass during 1965-1998 and nutrients during 1990-1998 and chlorophyll-a during 1995-1998 were used in this study. These data were obtained from the serial oceanographic observations in Korean waters carried out by the National Fisheries Research and Development Institute. In 1995 the C. polykrikoides bloom began in the coastal area around Narodo Island in August and consequently occurred to the whole coastal area of the South and East Seas of Korea. During June-October 1995, the coastal environment was unusual compared with the long-term means during 1965-1998. In June 1995, sea surface temperature was 1-2$^{\circ}C$ warmer than in other years in all coastal areas, while salinity was high only to the east of Jeju Island. In August 1995, a strong coastal front appeared inshore of a line between Jeju and Tsushima Islands. In particular, a strong coastal front which showed the characteristics of upwelling front occurred in the coastal area around Narodo and Sorido Islands, not only because of a strong intrusion of the Tsushima Warm Current but also because of the upwelling of cold bottom water. Salinity was low in the neighboring waters of western side of Jeju Island. Nutrients and chlorophyll-a were high in the inshore area between Narodo and Sorido Islands in 1995 in contrast with the other years and areas. Zooplankton showed an unusually high abundance in the coastal area in October 1995. We conclude that the Tsushima Warm Current strongly influenced the South Sea of Korea in 1995 and created strong upwelling front bordering cold upwelled water in the coastal area around Narodo and Sorido Islands. It leads us that these physical structures introduce the favorable environment for the development of C. polykrikoides blooms. We suggest that C. polykrikoides has a bio-physical tolerance of high shear and stress and prefers frontal and upwelling relaxed areas as its habitat. We also find that nutrients were not supplied to the coastal area from the offshore where a low salinity water mass with high nutrients appeared around Jeju Island. Because the strong upwelling front protect the reach of offshore low saline water mass. The main source of nutrients was the upwelled water mass in the coastal area of Wando-Narodo-Sorido.

• Ocean and Polar Research
• /
• 제30권4호
• /
• pp.379-399
• /
• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.