• Journal of Astronomy and Space Sciences
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• v.13 no.2
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• pp.52-66
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• 1996

In this paper, we present the design methodology of KASCOM(KAIST satellite computer), the experimental on-board computer system of KITSAT-2. The design of the on-board computer system should consider the following constraints: operational throughput, fault tolerant input-output, low power, size, weight, and radiation hardness. KASCOM is designed to satisfy these constraints. This paper also presents the implementation and testing details of KASCOM. Finally, the in-orbit operational results are presented. The results show that about 2 SEU errors occur for the program memory(1Mbit SRAM) in a day, while 3.7 SEU errors occur for the data memory(4Mbit SRAM). This implies that high-integrated memories are more susceptible to the radiation environment than low-integrated memories.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.390-390
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• 2012

Information technology industries has grown rapidly and demanded alternative memories for the next generation. The most popular random access memory, dynamic random-access memory (DRAM), has many advantages as a memory, but it could not meet the demands from the current of developed industries. One of highlighted alternative memories is magnetic random-access memory (MRAM). It has many advantages like low power consumption, huge storage, high operating speed, and non-volatile properties. MRAM consists of magnetic-tunnel-junction (MTJ) stack which is a key part of it and has various magnetic thin films like CoFeB, FePt, IrMn, and so on. Each magnetic thin film is difficult to be etched without any damages and react with chemical species in plasma. For improving the etching process, a high density plasma etching process was employed. Moreover, the previous etching gases were highly corrosive and dangerous. Therefore, the safety etching gases are needed to be developed. In this research, the etch characteristics of CoFeB magnetic thin films were studied by using an inductively coupled plasma reactive ion etching in $CH_4/O_2/Ar$ gas mixes. TiN thin films were used as a hardmask on CoFeB thin films. The concentrations of $O_2$ in $CH_4/O_2/Ar$ gas mix were varied, and then, the rf coil power, gas pressure, and dc-bias voltage. The etch rates and the selectivity were obtained by a surface profiler and the etch profiles were observed by a field emission scanning electron microscopy. X-ray photoelectron spectroscopy was employed to reveal the etch mechanism.

• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.1-5
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• 2005

Electric double layer capacitors(EDLCS) based on the charge stored at the interface between a hi팀 surface area carbon electrode and an organic electrolyte solution are widely used as a maintenance-free power source for IC memories and microcomputers. The achievement of the excellent performance of the capacitor requires an electrolyte solution which provides high conductivities over a wide temperature range and good electrochemical stabilities to allow the capacitor to be operated at high voltage. The electrochemical capacitor using a carbon material as electrodes and using an organic electrolyte with $1M-LiPF_6$ in PC-GBL-DEC(volume ratio 1:1:2) has specific capacitance of 64F/g.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.12
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• pp.685-697
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• 2001

Cache memories are small fast memories used to temporarily hold the contents of main memory that are likely to be referenced by processors so as to reduce instruction and data access time. In this paper, we represent analytical models of instruction fetch process for four types of instruction cache structures that can be used for superscalar processors. In the models, we define various kinds of architectural parameters and take cache miss and branch misprediction into consideration. To prove the correctness of the proposed models, we performed extensive simulations and compared the results with the analytical models. Simulation results showed that the proposed model can estimate the instruction fetch rate accurately within 10% error in most cases. Both analytical model and simulation show that the increase of cache misses reduces the instruction fetch rate more severely than that of branch misprediction does. However, the analytical model can explain the causes of performance degradation which cannot be uncovered by the simulation method only. The model is also able to provide exact relationship between cache miss and branch misprediction for instruction fetch analysis.

• Lingua Humanitatis
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• v.1 no.2
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• pp.179-196
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• 2001

According to Formalist theory, form is not separate from content. Form does not merely convey or express content but can itself produce meaning. The close correlation of the narrative structure, more specifically the time structure of the narrative, and the narrative style of Kim Seung-Ok′s short story′"Travel in Mujin" provides a good example of this argument. The story opens with the first-person narrator, currently living in the bustling city of Seoul, back in his small provincial home town Mujin, where he brings up memories that had been hitherto suppressed. The revived memories are ordered into the narrator′s present thought structure, in effect bridging the vast psychological rift between the lost past and the present. The narrator′s travel in Mujin thus becomes a psychological journey, and Mujin becomes a psychological space where the narrator can experience the continuity of his own being. The "narrating I" excludes the principles of reality from his narrative, concentrating on the inner thoughts, recollections, psychological experience, and the level of consciousness of the "narrated I." This narrative attitude or style expresses the narrator-protagonist′s acceptance and affirmation of the thoughts and actions occur in Mujin (which he had till now been resistant to). It is also an affirmation of the narrative act itself. Before the travel back to Mujin, the narrator-protagonist′s thoughts about his home town was ambivalent-an attitude originating from nostalgia, together with the narrator-protagonist′s ambivalent attitude toward his youthful past. It is a reflection of the narrator-protagonist′s desire for purity intermingled with a disdain for his enervated existence in Seoul. This ambivalence is resolved by the "I" of the narrative present, and Mujin enables him to come to a renewed affirmation of his life.

• Lingua Humanitatis
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• v.1 no.2
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• pp.91-104
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• 2001

Ford Madox Ford, the early twentieth-century writer most famous for his novel The Good Soldier, perceived his "business in life [as an] ... attempt to discover and to try to let you see where you stand." With this grand purpose in mind, Ford disregarded distinctions of genre in his prolific output of what we would consider novels, memoirs, literary criticism, travel writing, and history. Claiming that "the Novelist ... [is a] historian of his own time," Ford sought his own version of the "truth," a truth that was more faithful to his own subjective impressions than to verifiable "fact." Among these works that depict his age are a series of "memoirs" or "reminiscences," works published from the 1910s to the 1930s which carry out his Impressionistic purpose. What lies behind these memoirs is Ford′s view that his own individual history can be understood as his contemporary society′s collective history. This article explores Ford′s experimentation with boundaries of fact and fiction, and history and narrative, as he employs and expands the memoir form. In particular, 1 focus on two works, Memories and Impressions (1911) and It Was the Nightingale (1933), and Ford′s techniques in these memoirs, such as 1) the adoption of fictional personae from which to comment on his society at large and 2) the use of emblematic "parables" to encapsulate larger lessons of life within the minutiae of existence. Current theorists on the memoir form share interests in these questions of genre and of the social role of the memoir Nancy Miller, for instance, terms the memoir "the record of an experience in search of a community." This article engages these current discussions of the memoir genre by examining Ford′s early twentieth-century examples as innovative experiments that play with the boundaries between fiction and history, and personal impressions and collective truth.

• Korean Journal of Optics and Photonics
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• v.11 no.1
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• pp.58-64
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• 2000

Assuming that the performance of holographic storage media is ideal, we estimate the area storage density of disk-type holographic memories, when the method of either angle multiplexing, or rotational multiplexing, or both are used. The area storage density is strongly dependent on the f numbers (ratio of focal length to diameter) of both the Fourier transform lens in the signal arm, denoted by $F/#_2$, and the angle range over which the reference beam is incident (or, the equivalent f number corresponding to the angle range denoted by $F/#_1$). The area storage density is largely independent of the pixel pitch of the spatial light modulator when the Fourier plane holograms are recorded, while it is sensitive to the pixel pitch when the image plane holograms are recorded. In general, to obtain high area storage density, the Fourier or at least near Fourier plane holograms rather than the image plane holograms should be recorded. In addition, when the thickness of the recording materials are less than approximately $500\mu\extrm{m}$, rotational multiplexing gives higher area storage densities than angle multiplexing does. To increase the storage density further, however, it is desirable to use both of the two multiplexing methods in combination.nation.

• Journal of Korean Society of Archives and Records Management
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• v.11 no.1
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• pp.299-326
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• 2011

This paper surveyed records and archives which the railroad stations in Busan possesses and illustrated the status of them. Also we examined whether records and archives of railroad stations contain the memories of localities or not. We visited 17 railroad stations in Busan and we found that 1) the archives in railroad station are fugitive archives 2) the records or archives are classified into five categories, 'station's history', 'report on station-adjacent area', 'report of drive and transport', 'photos', and 'other materials' 3) the volume of such archives in 17 stations are different because of disposal or missing 4) Each archives in same category have same form. Especially the descriptions and images in 'station's history', 'report on station-adjacent area' represent much to memories of locality, but we also must examine the public records, private records related railroad station in Busan for documenting localities. To bridge the gap we suggest to collect oral records by relevant persons.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.2
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• pp.176-183
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• 2017

There is a problem of long erase and program times in testing large-density memories. Also, there is a need of testing the VT voltages of EEPROM cells at each step during the reliability test. In this paper, a cell verification module is designed for a 512kb EEPROM and a CG (control gate) driver is proposed for measuring the VT voltages of a split gate EEPROM having negative erase VT voltages. In the proposed cell verification module, asymmetric isolated HV (high-voltage) NMOS devices are used to apply negative voltages of -3V to 0V in measuring erase VT voltages. Since erasing and programming can be done in units of even pages, odd pages, or a chip in the test time reduction mode, test time can be reduced to 2ms in testing the chip from 4ms in testing the even and the odd pages.