• 한국전기전자재료학회논문지
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• 제17권12호
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• pp.1264-1270
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• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After making symmetric thyristor dies with a voltage rating of 1,600 V from 350 $\mu$m thickness of 60 $\Omega$ㆍcm NTD-Si wafer and 200 $\mu$m width of n-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7 MeV proton beam showed a superior trade-off relationship of $V_{TM}$ = 1.55 V and $t_{q}$ = 15 $\mu$s attributed to a very narrow layer of short carrier lifetime(～1 $\mu$s) in the middle of its n-base drift region. To explain the small increase of $V_{TM}$ , we will introduce the effect of carrier compensation at the low carrier lifetime region by the diffusion current.ffusion current.t.

• 한국전기전자재료학회논문지
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• 제33권2호
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• pp.109-113
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• 2020

A power device is a component used as a switch or rectifier in power electronics to control high voltages. Consequently, power devices are used to improve the efficiency of electric-vehicle (EV) chargers, new energy generators, welders, and switched-mode power supplies (SMPS). Power device designs, which require high voltage, high efficiency, and high reliability, are typically based on MOSFET (metal-oxide-semiconductor field-effect transistor) and IGBT (insulated-gate bipolar transistor) structures. As a unipolar device, a MOSFET has the advantage of relatively fast switching and low tail current at turn-off compared to IGBT-based devices, which are built on bipolar structures. A superjunction structure adds a p-base region to allow a higher yield voltage due to lower R_DS (on) and field dispersion than previous p-base components, significantly reducing the total gate charge. To verify the basic characteristics of the superjunction, we worked with a planar type MOSFET and Synopsys' process simulation T-CAD tool. A basic structure of the superjunction MOSFET was produced and its changing electrical characteristics, tested under a number of environmental variables, were analyzed.

• 한국식생활문화학회지
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• 제26권3호
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• pp.211-219
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• 2011

To examine the key success factors for long-lasting restaurants, we visited 10 restaurants with 30 or more than 30 years of tradition, located in Seoul and Gyeonggi-do districts, to research these restaurant menus and customer characteristics by observation and interview. The results were analyzed using descriptive statistics. The outstanding feature noted was that each and every restaurant had its own simple and specialized menu. We found that this feature created a virtuous circle that reinforced itself through a positive feedback loop. The simple and specialized menu increased both the cooking efficiency and food quality while it reduced both food and labor costs, this enabled the customers to eat at an affordable price and have generous servings. This lead to customer satisfaction and revisits to the restaurant, which triggered word-of-mouth referral and expansion of their customer base. This in turn created higher operating profit margins that could be reinvested in the business. The secret recipes for cooking, invented by their founders, were passed on from generation to generation. Their customer base included customers of all ages from children to senior people. And their regular customers consisted of neighboring office workers and families traveling from a long distance. We hope that our findings on long-lasting restaurants, especially of the virtuous cycle created due to the simple and specialized menus with secret recipes, will contribute to the development of Korean style long-lasting restaurant model.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.271-275
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• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After fabricating symmetric thyristor dies with a voltage rating of 1,600V from $350{\mu}m$ thickness of $60{\Omega}cm$ NTD-Si wafer and $200{\mu}m$ width of N-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7MeV proton beam showed a superior trade-off relationship of $V_{TM}=1.55V\;and\;t_q=15{\mu}s$ attributed to a very narrow layer of short carrier lifetime(${\sim}1{\mu}s$) in the middle of its N-base drift region. To explain the small increase of $V_{TM}$, we will introduce the effect of carrier compensation by the diffusion current at the low carrier lifetime region.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.3103-3103
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• 2001

NIR has been extensively used to predict directly measurable properties of materials that are important to the appropriate industries. Commonly, NIR is used to perform fast, routine tests to improve control response as against the response time for the (normally chemical) base test. This paper discusses the use of NIR to measure indirect properties of materials. In these cases, the pure chemical or physical tests are either unable measure the appropriate parameters (eg GMO modification) or there are mitigating effects that are not properly addressed by the base tests. In particular, we looked at the digestible portion of amino acids within meat and bone meal. This is the desired response measurement by end-users of the product (intensive livestock producers) but is currently unable to be offered as a measurement by producers. The base test method is by controlled feeding trials. These are somewhat cumbersome, taking 2-3 months, involving several sets of animals, and considerable expense. A shortened test (feed trial based) would be of little use, as the precision blows out over short period feeding trials. For example, a rat ileal digestibility test requires around 2 months, and costs some $USD1000. This is clearly impractical test for a producer involved in continuous production, with a 1-2 day turn around. While the amino acid abundance is accessible chemically, the uptake of amino acids into usable material by mammalian species is not simply related to the measured abundance within the material. There are many co-related material properties that might help or hinder uptake, some chemical based (eg protein damage), some indirect (eg palatability), some physiological (intestinal tract response vs speed of throughput). We discuss the approaches taken to provide a suitable reference data set, and present the derived prediction and validation relationships.

• 펄프종이기술
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• 제30권3호
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• pp.74-83
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• 1998

The phenomenon of decrease in sizing efficiency when the stock temperature is increased is well recognized as summer sizing, and this is believed to be caused by uneven distribution of sizing agents on paper surface most often incurred by coagulation of sizing agents. When unevenly sized paper is used as coating base stock, nonuniform consolidation of the coating layer may result, which, in turn, causes uneven distribution of binder on coating surface. This causes nonuniform ink absorption to produce print mottle. In this study the effects of simple or polymeric electrolytes, storage temperature and time on the coagulation of cationic dispersed rosin size were investigated using a turbidity measurement method which was verified to correlate well with the particle size of rosin emulsion or its coagulates. Handsheets sized with rosin dispersions coagulated under various conditions were prepared and their sizing degree and coated paper properties including gloss and ink density were examined. The relationship between the sizing nonuniformity of coated papers and its ink absorption property was evaluated. Turbidity of rosin emulsion increased as the storage temperature and time were increased. Addition of simple or polymeric electrolytes caused reduction in $zeta$ -potential of the rosin dispersion and accelerated the coagulation tendency substantially. Reversion of the $zeta$ -potential of rosin dispersion, however, did not occur when coagulation was induced with simple electrolytes. On the other hand, addition of an anionic polyelectrolyte reversed the $zeta$ -potential of the flocculated rosin dispersion. This indicated that electrical double layer compaction and bridging flocculation were coagulation mechanisms for simple and polymeric electrolytes, respectively. Sizing degree decreased as coagulation of rosin was increased. Paper gloss, ink gloss and ink density were increased when sizing degree of base stock was increased most probably due to prevention of base paper swelling and increased binder migration to coating surface. This suggested that uneven printing ink density occurred when uneven sizing development was induced by coagulation of rosin particles.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.381-388
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• 2000

The steel piers and the concrete-filled steel piers, in spite of reasonable strength, high ductility, small section, and fast construction, have not been considered as the alternatives to the RC piers even in the highly populated urban area where aseismic safety, limited space and fast construction are indispensably required. In this paper, a steel pier and 4 box type concrete-filled steel piers were tested with the quasi-static cyclic loading to estimate the ductility and the strength. Additional devices such as base rib, turn-buckle, and anchor bolted added at the to increase the ductility with minimum additional cost. The result showed that the concrete filled-in steel piers had higher energy absorbtion and strength than steel piers had, but also showed that slight overlooking in the design and fabrication could lead to the abrupt fracture just after small local buckling at the bottom.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2005년도 ISMP
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• pp.111-129
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• 2005

Pop provides OEMs and EMS with a platform to cost effectively expand options for logic + memory 3D integration - Expands device options by simplifying business logistics of stacking - Integration controlled at the system level to best match stacked combinations with system requirements - Eliminates margin stacking and expands technology reuse - Helps manage the huge cost impacts associated with increasing demand for multi media processing and memory. PoP is well timed to enable and leverage: - Mass customization of systems for different use (form, fit and function) requirements o Bband and apps processor + memory stack platforms - Logic transition to flip chip enables PoP size reduction o Area and height reduction. Industry standardization is progressing. Amkor provides full turn-key support for base package, memory package and full system integration.

• Geomechanics and Engineering
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• 제8권4호
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• pp.523-540
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• 2015

Based on limit equilibrium principles, this study presents a theoretical derivation of a new analytical formulation for estimating magnitude and lateral earth pressure distribution on a retaining wall subjected to seismic loads. The proposed solution accounts for failure wedge inclination, unit weight and friction angle of backfill soil, wall roughness, and horizontal and vertical seismic ground accelerations. The current analysis predicts a nonlinear lateral earth pressure variation along the wall with and without seismic loads. A parametric study is conducted to examine the influence of various parameters on lateral earth pressure distribution. Findings reveal that lateral earth pressure increases with the increase of horizontal ground acceleration while it decreases with the increase of vertical ground acceleration. Compared to classical theory, the position of resultant lateral earth force is located at a higher distance from wall base which in turn has a direct impact on wall stability and economy. A numerical example is presented to illustrate the computations of lateral earth pressure distribution based on the suggested analytical method.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1997년도 춘계학술대회
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• pp.3-5
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• 1997

Properties of a good drug include safety, efficacy, half-life and bioavailability. With the current approach to drug discovery based on receptor-based and cell-based screening methods, compounds are frequently moved into development with poor bioavailability. With low bioavailability, drug administration is typically limited to parenteral routes, thus limiting the potential wide-spread utility of these therapeutic agents. The first and most important factor limiting a drug's bioavailability is the intestinal membrane permeability which in turn determines the maximum fi:action of the dose administered that can be absorbed. We have recently utilized new intubation methods for performing permeability measurements in humans and establishing a fundamental human data base for correlating intestinal jejunal membrane permeabilities with permeabilities determined in other systems, e.g., animals, tissue culture, as well as physical chemical properties.