• Journal of the Semiconductor & Display Technology
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• v.23 no.1
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• pp.84-87
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• 2024

A water sterilization system is developed utilizing a 275 nm-wavelength LED light source equipped with a TIR lens. The system's light source is constructed by combining a 275 nm-wavelength UVC LED, known for its germicidal properties, with a TIR lens having a direction angle of 6.8 degrees. The optical simulation software 'LightTools' is employed to design and optimize the intensity of deep ultraviolet sterilizing light irradiation, its distribution, and sterilization capacity. In the inactivation experiment with E. coli, the water sterilizer system achieved a sterilization rate of 78.92 % while maintaining a water flow capacity of 50 L/min. Compared to the conventional mercury lamp light source water sterilizer system, the UVC LED water sterilizer system addresses environmental concerns related to mercury usage and offers advantages in terms of lifespan and durability.

• Journal of Korean Society of Forest Science
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• v.111 no.3
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• pp.385-393
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• 2022

The study was carried out in Pocheon-si, Gyeonggi-do from March to December in 2019 to compare and analyze the water use strategies of two co-occurring tree species, Pinus densiflora and Quercus serrata, both native and dominant in Korea's forest ecosystems. Through seasonal changes, we measured environmental variables such as air temperature, relative humidity, precipitation, net radiation, and soil water content. Sap flow densities of P. densiflora (n = 6) and Q. serrata (n = 3) were measured, along with environmental variables. The maximum sa pflow density for Q. serrata almost doubled that of P. densiflora during the growing season, while the maximum sap flow densities in both Q. serrata and P. densiflora peaked in September and August, respectively. Net radiation and vapor pressure deficit, but not air temperature, were the major environmental variables significantly affecting sap flow density. Analysis of hysteresis revealed that P. densiflora exhibited isohydric behavior, while Q. serrata showed anisohydric behavior. Analysis of crown conductance revealed similar trends as sap flow density, i.e., the crown conductance of Q. serrata was twice that of P. densiflora during the growing period. The study compared and analyzed the water use strategies between two co-occurring species. To better understand the underlying mechanisms of water use, more research on both physiological and morphological traits are needed.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1058-1062
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• 2005

통상 방조제 배수갑문의 방류능력은 위어공식 또는 오리피스공식을 이용하여 산정하는데, 이 경우 지형특성, 배수갑문 형상에 따른 흐름의 간섭현상, 유입부와 유출부의 형상 등이 방류량에 미치는 영향을 고려하지 못한다. 본 연구에서는 도류벽, 배수문, 물받이 등 방조제 배수갑문의 형상과 배치가 방류량에 미치는 영향을 상용 프로그램인 FLOW-3D를 이용하여 정량적으로 해석하였다. 이를 통해 배수갑문의 방류능력과 유황을 개선할 수 있는 방안을 도출하였다. 본 연구에서는 시화조력발전소를 대상으로 배수갑문의 방류능력 개선에 3차원 수치모의가 효과적으로 적용될 수 있음을 보였다. 본 연구에서 도출한 주요 결론은 다음과 같다. 1) 유출부측의 물받이길이를 40 m 증가시킴에 따라 전체 방류량은 계획안에 비해 약 $10\% 증가하는 것으로 나타났다. 2) 물받이 끝과 원지반의 연결부 사면을 1:1에서 1:5의 완경사로 변화시킴에 따라 전체 방류량은 약 $2\%$ 증가하는 것으로 나타났다. 3) 배수문과 수차발전 구조물 사이의 유선형 연결구조물을 제거함에 따라 전체 방류량은 약 $3\%$ 증가하는 것으로 나타났다. 4) 도류벽의 접근각도를 $10^{\circ}$ 감소시키거나 증가시킴에 따라 전체 방류량은 약 $5\% 감소 또는 증가하는 것으로 나타났다. 본 연구는 배수갑문의 설계시 방류능력 개선을 위해서는 수리학적 검토가 필요하며 수치모형실험이 수리모형실험과 더불어 유용한 해석도구로 이용될 수 있음을 보인 것으로, 이후 관련 구조물의 설계시 참고자료로 이용 가능할 것으로 사료된다.다. 실험 결과, Escarameia와 May가 제안한 공식을 더 확장하여 적용할 수 있는 실험 공식으로 개선하였으며 다양한 조건에 대한 실험을 수행하여 보다 정밀한 공식으로 개선할 수 있었다.$10,924m^3/s$ 및 $10,075m^3/s$로서 실험 I의 $2,757m^3/s$에 비해 통수능이 많이 개선되었음을 알 수 있다.함을 알 수 있다. 상수관로 설계 기준에서는 관로내 수압을 $1.5\~4.0kg/cm^2$으로 나타내고 있는데 $6kg/cm^2$보다 과수압을 나타내는 경우가 $100\%$로 밸브를 개방하였을 때보다 $60\%,\;80\%$ 개방하였을 때가 더 빈번히 발생하고 있으므로 대상지역의 밸브 개폐는 $100\%$ 개방하는 것이 선계기준에 적합한 것으로 나타났다. 밸브 개폐에 따른 수압 변화를 모의한 결과 밸브 개폐도를 적절히 유지하여 필요수량의 확보 및 누수방지대책에 활용할 수 있을 것으로 판단된다.8R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며 $10\% 경사일 때를 기준으로 $Ro(mm)=Ro_{10}{\times}0.797{\times}e^{-0.021s(\

• 한국해양학회지
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• v.19 no.2
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• pp.141-152
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• 1984

In order to investigate the circulation dynamics of the Keum River estuary, 300velocity fields obtained at six sites over two tidal cycles by using instantaneous profiling technique were analyzed in detail. In this investigation, the variability of shear velocity, bottom shear stress, drag coefficient, and roughness length scale were confirmed. The measured values of the bottom boundary drag coefficient show wide range of variations, i.e., C$\_$100/=6.78${\times}$10$\^$-5/∼1.15${\times}$10$\^$-1/, and the mean of 300 measurements is 1.6${\times}$10$\^$-2/. The relationship between U* and C$\_$100/ also show the scatter in values. However, overall mean values over two tidal cycles at 6 stations show that if U* 1cm/s, C$\_$100/ is unpredictable, if U* 1cm/s, C$\_$100/ increase with U*. The values of Re$\_$100/ and C$\_$100/ have scatter. But the overall mean values over two tidal cycles show that if Re$\_$100/ 3.6${\times}$10$\^$5/, C$\_$100/ is unpredictable, if Re$\_$100/ 3.6${\times}$10$\^$5/, C$\_$100/=1.4${\times}$10$\^$-2/. Finally the flow regime of the Keum River estuary was classified as "subcritical fully turbulent" flow.

• Journal of the Korean Vacuum Society
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• v.21 no.6
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• pp.333-341
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• 2012

Indium Tin Oxide (ITO) thin films were prepared by RF magnetron sputtering with different flow rates of $O_2$ gas from 0 to 12 sccm. Electrical and optical properties of these films were characterized and analyzed. ITO deposited on soda lime glass and RF power was 2 kW, frequency was 13.56 MHz, and working pressure was $1.0{\times}10^{-3}$ Torr, Ar gas was fixed at 1,000 sccm. The transmittance was measured at 300~1,100 nm ranges by using Photovoltaic analysis system. Electrical properties were measured by Hall measurement system. ITO thin films surface were measured by Scanning electron microscope. Atomic force microscope surface roughness scan for ITO thin films. ITO thin films secondary electron emission coefficient(${\gamma}$) was measured by ${\gamma}$-Focused ion beam. The resistivity is about $2.4{\times}10^{-4}{\Omega}{\cdot}cm$ and the weighted average transmittance is about 84.93% at 3 sccm oxygen flow rate. Also, we investigated Work-function of ITO thin films by using Auger neutralization mechanism according to secondary electron emission coefficient(${\gamma}$) values. We confirmed secondary electron emission peak at 3 sccm oxygen flow rate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.4
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• pp.213-223
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• 2004

The discharges of groundwater flow were estimated using Darcy's method along the coastal zone in the Masan Bay. The estimates using the information, i.e., groundwater level, location of the observation well, hydraulic conductivity, the thickness of the aquifer, and coastline length, were 1.65% of the precipitation of the watershed. The estimated groundwater discharges through fractured rock aquifer and the aquifer with sedimentary material were $0.7\times10^4$$m^2/year$and $1.0\times10^7$$m^3/year$ respectively. Whereas, the discharge estimated by KORDI (2003) using isotopes method is about 20 times larger than the estimates from this study because of the influence of the re-circulated seawater through the coastal zone aquifer. In order to quantify this effect in detail, the groundwater levels and salinity changes in the observation wells located in the coastal zone should be continuously monitored and analyzed.

• Structural Engineering and Mechanics
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• v.67 no.5
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• pp.493-504
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• 2018

In this paper, the tensile failure behaviour of transversally bedding layers was numerically simulated by using particle flow code in two dimensions. Firstly, numerical model was calibrated by uniaxial, Brazilian and triaxial experimental results to ensure the conformity of the simulated numerical model's response. Secondly, 21 circular models with diameter of 54 mm were built. Each model contains two transversely bedding layers. The first bedding layer has low mechanical properties, less than mechanical properties of intact material, and second bedding layer has high mechanical properties, more than mechanical properties of intact material. The angle of first bedding layer, with weak mechanical properties, related to loading direction was $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$ while the angle of second layer, with high mechanical properties, related to loading direction was $90^{\circ}$, $105^{\circ}$, $120^{\circ}$, $135^{\circ}$, $150^{\circ}$, $160^{\circ}$ and $180^{\circ}$. Is to be note that the angle between bedding layer was $90^{\circ}$ in all bedding configurations. Also, three different pairs of the thickness was chosen in models; i.e., 5 mm/10 mm, 10 mm/10 mm and 20 mm/10 mm. The result shows that In all configurations, shear cracks develop between the weaker bedding layers. Shear cracks angel related to normal load change from $0^{\circ}$ to $90^{\circ}$ with increment of $15^{\circ}$. Numbers of shear cracks are constant by increasing the bedding thickness. It's to be note that in some configuration, tensile cracks develop through the intact area of material model. There is not any failure in direction of bedding plane interface with higher strength.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.131-134
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• 2000

Increased temperature adversely affects the reliability of a device. So, package material should have high thermal diffusion, i.e., high thermal conductivity. And, there are several other physical properties of polymeric materials that are important to microelectronics packaging, some of which are a low dielectric constant, a low coefficient of thermal expansion (CTE), and a high flexural strength. In this study, to get practical maximum packing fraction of AIN (granular type) filled EMC, the properties such as the spiral flow, thermal conductivity, CTE, and water resistance of AIN-filled EMC (65-vol%) were evaluated according to the size of AIN and the filler-size distribution. Also, physical properties of AIN filled EMC above 65-vol% were evaluated according to increasing AIN content at the point of maximum packing fraction (highly loading condition). The high loading conditions of EMC were set $D_L/D_S$=12 and $X_S$=0.25 like as filler of sphere shape and the AIN filled EMC in this conditions can be obtained satisfactory fluidity up to 70-vol%. As a result, the AIN filled EMC (70-vol%) at high loading condition showed improved thermal conductivity (about 6 W/m-K), dielectric constant (2.0~3.0), CTE(less than 14 ppm/$^{\circ}C$) and water resistance. So, the AIN filled EMC (70-vol%) at high loading condition meets the requirement fur advanced microelectronic packaging materials.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.2
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• pp.34-44
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• 2002

Approximately 70 percent of shop's hull plate consists of three-dimensional curved shell. Concerning with the research on the automation of plate forming many studies have been carried out for the last decade. The purpose of this study is to develop the simulator of heating on the basis of the reasonable mechanical model representing a heating phenomenon. The beating experiment has been carried out with varying parameters influencing on the results of heating information at the kinematics analysis, simulatorestimate the shape of deformed plate that process along the processing information. When we get the initial shape and the object shape, we calculate the processing information first, using kinematics analysis. In a simulator we estimate deformed shape from the processing information. After this we compare deformed shape and object shape. If the error of deformed shape and object shape is in the proper limits, that information is determined the final processing information. Else we repeat the process changing variable.

• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.10-14
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• 2015

This paper reports the results of a study on the optimization of the etching profile, which is an important factor in deep-reactive-ion etching (DRIE), i.e., dry etching. Dry etching is the key processing step necessary for the development of the Internet of Things (IoT) and various microelectromechanical sensors (MEMS). Large-area etching (open area > 20%) under a high-frequency (HF) condition with nonoptimized processing parameters results in damage to the etched sidewall. Therefore, in this study, optimization was performed under a low-frequency (LF) condition. The HF method, which is typically used for through-silicon via (TSV) technology, applies a high etch rate and cannot be easily adapted to processes sensitive to sidewall damage. The optimal etching profile was determined by controlling various parameters for the DRIE of a large Si wafer area (open area > 20%). The optimal processing condition was derived after establishing the correlations of etch rate, uniformity, and sidewall damage on a 6-in Si wafer to the parameters of coil power, run pressure, platen power for passivation etching, and $SF_6$ gas flow rate. The processing-parameter-dependent results of the experiments performed for optimization of the etching profile in terms of etch rate, uniformity, and sidewall damage in the case of large Si area etching can be summarized as follows. When LF is applied, the platen power, coil power, and $SF_6$ should be low, whereas the run pressure has little effect on the etching performance. Under the optimal LF condition of 380 Hz, the platen power, coil power, and $SF_6$ were set at 115W, 3500W, and 700 sccm, respectively. In addition, the aforementioned standard recipe was applied as follows: run pressure of 4 Pa, $C_4F_8$ content of 400 sccm, and a gas exchange interval of $SF_6/C_4F_8=2s/3s$.