• Journal of the korean Society of Automotive Engineers
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• 제15권2호
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• pp.53-63
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• 1993

A numerical modeling technique is proposed for computer simulations of high speed valve train dynamic terms in the valve spring reaction forces are calculated using linear vibration theory for given kinematic valve motions. Because the spring dynamics are analyzed before the time stepping integration, spring surge phenomena can be included without using additional computer time. In addition to that, steady state response of the valve dynamics can be obtained by just one cycle simulation. Consequently, valve train dynamics can be simulated very quickly without noticeable errors in accuracy. The experimental result prove the computer model developed here is accurate and also computationally efficient. The model is especially useful for cam profile optimizations.

• Proceedings of the Korean Nuclear Society Conference
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.973-979
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• 1995

The input equivalent noise charge (ENC) of hydrogenated amorphous silicon radiation detector diodes was measured and analyzed. The noise sources of amorphous silicon diodes were analyzed into three sources; shot noise, flicker noise and thermal noise from the contact resistance. By comparing the measured ENC with the calculated signal charge in uniform generation case, the signal-to-noise ratio (S/N) for the sample diodes is estimated as a function of the detector bias and the shaping time of Gaussian pulse shaper. The maximum S/N occurred at the bias level just above the full depletion voltage for shaping time of 2∼3 ${\mu}$sec. The developed method is useful in optimum design or amorphous silicon p-i-n diodes for charged particulate radiation spectroscopy.

• Proceedings of the Korean Institute of Interior Design Conference
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• 한국실내디자인학회 2007년도 추계학술발표대회 논문집
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• pp.84-88
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• 2007

Movie has a light, colors, and texture in the space and a design. Movie is a ovation of the 3-dimensional reality with time and space. Just like a movie, a space can also express time, personality of characters and background stories. Symbolization of a space tells philosophy and emotions, making meaning of the space abundant and consistency in entire composition of the space. Expression of beauty through order of space inside proves meaning of space. Think that can do and present to production methodology of space design to universalize ureas through symbolic productions that is based on story.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• 제9권1호
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• pp.7-12
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• 2010

In this paper, we propose a new prioritized Optical Burst Switching (OBS) protocol based on a hop count, which can provide an efficient utilization in optical Wireless networks. Under several legacy schemes, a switch drops the burst with a shorter time among ones regardless of its traversed hop counts. As a result, the dropped burst that have been traversed more hops might cause to waste bandwidth than the one traversed a few hops. Noting that this problem, we propose the Just Enough Time (JET) with a hop count scheme which can reduce the wasted bandwidth by prioritizing the burst traversed more hops over others. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the burst blocking probability and the link utilization.

• Educational Technology International
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• 제10권2호
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• pp.1-27
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• 2009

Technology use can dramatically enhance teachers' performance in teaching and administrative tasks. An Electronic Performance Support System (EPSS) is a versatile tool that could provide just-in-time and on-the-job training when teachers need it. In order to design an effective EPSS for teachers, it is critical to identify their needs. This study used interviews to identify teachers' needs for technology by asking them about their workloads, the difficulty and time demands of tasks, and useful technologies. The implications of the findings for the design of an EPSS are discussed, including the necessity of an adaptive design of the EPSS.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제9권1호
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• pp.120-131
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• 2016

In this paper, a 512b MTP memory IP is designed by using MTP memory cells which are written by the FN (Fowler-Nordheim) tunneling method with only MV (medium voltage) devices of 5V which uses the back-gate bias, that is VNN (negative voltage). The used MTP cell consists of a CG (control gate) capacitor, a TG (tunnel gate) transistor, and a select transistor. To reduce the size of the MTP memory cell, just two PWs (P-wells) are used: one for the TG and the select transistors; and the other for the CG capacitor. In addition, just one DNW (deep N-well) is used for the entire 512b memory cell array. VPP and VNN generators supplying pumping voltages of ${\pm}8V$ which are insensitive to PVT variations since VPP and VNN level detectors are designed by a regulated voltage, V1V (=1V), provided by a BGR voltage generator.

• Magazine of the Korean Society of Agricultural Engineers
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• 제37권5호
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• pp.81-89
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• 1995

One of the most difficult problem to estimate the flood inflow is how to understand the effective rainfall. The effective rainfall is absolutely influenced by the condition of soil moisture in the watershed just before the storm event. DAWAST model developed to simulate the daily streamflow considering the meteologic and geographic characteristics in the Korean watersheds was applied to understand the soil moisture and estimate the effective rainfall rather accurately through the daily water balance in the watershed. From this soil moisture and effective rainfall, concentration time, dimensionless hydrograph, and addition of baseflow, the rainfall-runoff model for flood flow was developed by converting the concept of long-term runoff into short-term runoff. And, real-time flood forecasting model was also developed to forecast the flood-inflow hydrograph to the river and reservoir, and called RETFLO model. According to the model verification, RETFLO model can be practically applied to the medium and small river and reservoir to forecast the flood hydrograph with peak discharge, peak time, and volume. Consequently, flood forecasting and warning system in the river and the reservoir can be greatly improved by using personal computer.

• Journal of Veterinary Clinics
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• 제23권2호
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• pp.123-128
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• 2006

Production of cloned pigs by somatic cell nuclear transfer (SCNT) has unlimited value for developing critical biotechnology such as xenotransplantation. Various efforts have been made to establish this technology, and several litters of live piglets have been produced after transfer of SCNT embryos. However, the efficiency is very low compared to piglet production by artificial insemination or natural mating. So far, most studies have been limited to in vitro production of SCNT embryos. This study was conducted to standardize a surrogate recipient (gilts) for transfer of SCNT embryos to improve pregnancy rate. Potential surrogate gilts over 7 months of age were checked for their estrous status by observing external signs; vaginal fluid, vulva redness, vulva swelling, and standing response to back pressure. Viscosity of vaginal fluid was evaluated and classified as none (0), medium (1), and strong (2). Vulva redness and swelling was respectively assessed by none or shrink (0), medium (1), strong (2). Back pressure was estimated by an immediate move (0), standing less than 10 sec (1), and standing over 10 see (2). And then ovulation status of each surrogate was classified as pre-ovulation (PO-17 surrogates), just prior to ovulation (JPO-20 surrogates), in ovulation (IO-12 surrogates), just after ovulation (JAO-14 surrogates) and after ovulation (AO-24 surrogates) at the time of surgery for embryo transfer (ET). Real-time ultrasonographic scanners have been used for pregnancy diagnosis by observing amniotic vesicles. The first pregnancy diagnosis was done on Day 30 after ET and then repeated 2-week interval. In the results, SCNT embryos transferred into JPO surrogates gave better pregnancy rates (45%) than others (4% to 11%) on Day 30 after ET. These result indicates that surrogate gilts in a status just prior to ovulation can offer optimal condition to establish pregnancy by transfer of SCNT pig embryos.

• Journal of the Korean Society of Food Science and Nutrition
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• 제31권4호
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• pp.664-671
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• 2002

To investigate the effects of different type of dietary fat on survival metabolism of fasting rats, one group rats (FO) were fasted, another one group rats (BM) were fed normal diet and the others were fed only one of the following fat diets: beef tallow (FT), corn oil (FC), and perilla oil (FP) of 11.4g/kg respectively. Most FO group rats survived for 6 days and large part of the only-fat-diet groups rats survived for 16 days. Body weights of all rats in fasting and only-fat-groups, measured just one day prior to death owing to fasting or caloric malnutrition, decreased by 24.5%~25% only-fat to fasting rat somewhat extended the survival time but the specific properties of dietary fat types had no remarkably differential effect on survival time and body weight gain rate. The features of liver and kidney weight gain rate of all rats in fasting and only-fat-diet groups were similar to those of body weight gain rate. In FO groups blood levels of total-cholesterol, triglyceride, and glucose markedly reduced whereas GPT activities and BUN levels considerably increased as compared to BM group. However the types of dietary fat perse did not affect blood total cholesterol, triglyceride, glucose, BUN levels, and GPT activities in early stage of fasting in FC and FP group. GPT activities in rats of FP group just prior to death of starvation seemed to be affected by the dietary fat types. The results showed that only-fat-feeding to fasting rats somewhat extended survival time but the types of dietary fat had no remarkably differential effect on survival time and metabolism of fasting rats.

• Rapid Communication in Photoscience
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• 제4권1호
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• pp.25-28
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• 2015

The time-resolved photoexcitation dynamics of electrical conductivity of the magnetic organic superconductor ${\lambda}-(BETS)_2Fe_{0.45}Ga_{0.55}Cl_4$ has been studied with a nanosecond visible laser pulse at its three different phases, i. e., metallic phase, superconducting phase and insulating phase. A transient increase of the resistance is induced by photoirradiation at all the temperatures measured for all three phases, but the decay profile shows a significant temperature dependence. The relaxation rate in the metallic and insulating phase are different from each other, and the decay time is relatively faster and almost constant in the metallic phase. However, a prolongation of the relaxation time is observed at temperature just around the narrow superconducting phase. Nonbolometric (nonthermal) origin of the observed photoresponse of the electrical conductivity is confirmed in the superconducting phase.