• ETRI Journal
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• v.33 no.5
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• pp.802-805
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• 2011

This letter presents a K-band polarization reconfigurable antenna integrated with a silicon radio frequency MEMS switch into the form of a compact package. The proposed antenna can change its state from linear polarization (LP) to circular polarization (CP) by actuating the MEMS switch, which controls the configuration of the coupling ring slot. Low-loss quartz is used for a radiating patch substrate and at the same time for a packaging lid by stacking it onto the MEMS substrate, which can increase the system integrity. The fabricated antenna shows broadband impedance matching and exhibits high axial ratios better than 15 dB in the LP and small axial ratios in the CP, with a minimum value of 0.002 dB at 20.8 GHz in the K-band.

• ETRI Journal
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• v.35 no.4
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• pp.726-729
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• 2013

For secure multimedia communications, existing encryption techniques use an online session key for the key exchange, for which key size is limited to less than 10 digits to accommodate the latency condition caused by user devices only being able to handle low computational loads. This condition results in poor security of recorded encrypted data. In this letter, we propose a packet key scheme that encrypts real-time packets using a different key per packet for multimedia applications. Therefore, a key of a relatively small size can provide after-transmission confidentiality to data of a real-time session.

• Journal of electromagnetic engineering and science
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• v.14 no.3
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• pp.317-319
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• 2014

In this letter, a small-loop antenna for a mobile UHF RFID device is proposed. To achieve size reduction, a ferrite sheet optimized for a 900 MHz band is applied. The overall dimensions of the antenna are $46mm{\times}35mm{\times}0.24mm$, and it has a bandwidth of 45 MHz with a return loss of less than -6 dB. The proposed antenna satisfies near and far field UHF EPC global frequency band communications (902-928 MHz).

• Journal of the Korean Chemical Society
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• v.52 no.3
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• pp.303-314
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• 2008

The purpose of this study was to understand the experiment for measuring chemical reaction rate by precipitate formation and to develop experiments applying small-scale chemistry. For this study, the experimental method for measuring the effect of concentration and temperature on chemical reaction rates presented in the 10 high school science textbooks were classified by their experimental methods of confirming production. Subsequently, problems observed in carrying out the experiments for measuring chemical reaction rates by precipitate formation frequently presented in the 10 high school science textbooks were analyzed. Experiments applying small-scale chemistry were developed measuring chemical reaction rate by precipitate formation. According to the result of this study, there were some problems in the experimental method of precipitate formation for measuring chemical reaction rates presented in the high school science textbooks. Those problems in the science textbook experiments were insufficient specification of mixing methods of reaction solutions, obscurity of knowing when the character letter X disappeared, time delay in collecting the experimental data, formation of hazardous sulfur dioxide, uneasiness of fixing water bath container, controlling the reaction temperature, and low reproducibility. Those problems were solved by developing experiments applying smallscale chemistry. Presenting the procedure of mixing reaction solutions on the A4 reaction paper sheet made the experimental procedure clearly, using well plates and stem pipette shortened the reaction time and made it possible to continuously collect the experimental data. Furthermore, the quantity of hazardous sulfur dioxide was reduced 1/7 times and the time when the character letter X disappeared could be observed clearly. Since experiments for measuring the effect of concentration and temperature on chemical reaction rates could be performed in 30 minutes, the developing experiments applying SSC would help students understand the scientific concepts on the effect of concentration and temperature on chemical reaction rates with enough time for experimental data analysis and discussion.

• Journal of Arbitration Studies
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• v.17 no.1
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• pp.137-155
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• 2007

Since China joined the WTO, the trade between Korea and China has continued to grow by leaps and bounds, making both nations become mutually important trading partners to each other. The volume of trades with China showed a rapid upward trend with an average annual increase rate of 20% and the resultant dispute is also rising. Thus, this study was aimed to make some suggestions and come up with ways of responding claims by surveying Korean trading firms which have experience in making transactions with China to investigate the current status and the actual condition of their occurrence. As a result of this study, firstly, the main cause of such dispute was shown to be the failure to perform the agreement. Secondly, there were malty verbal agreements and due to a deterioration of trust in Chinese firms, the method of a letter of credit was adopted by many Korean firms. Thirdly, the payment and credit appeared to be most important in transactions with China. A credit inquiry is a must in future transactions with China. Fourthly, the indirect cause of the occurrence of trade claims was the difference in commercial practices and as for the way of settling disputes, the agreement through negotiations between the parties involved was the most. Fifthly, small and medium firms should make more of their credit and English proficiency than large ones do.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2002.05a
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• pp.111-116
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• 2002

The regularity effect for printed word recognition and naming depends on ambiguities between single letters (small grain-size) and their phonemic values. As a given word is repeated and becomes more familiar, letter-aggregate size (grain-size) is predicted to increase, thereby decreasing the ambiguity between spelling pattern and phonological representation and, therefore, decreasing the regularity effect. Lexical decision and naming tasks studied the effect of repetition on the regularity effect for words. The familiarity of a word from was manipulated by presenting low and high frequency words as well as by presenting half the stimuli in mixed upper- and lowercase letters (an unfamiliar form) and half in uniform case. In lexical decision, the regularity effect was initially strong for low frequency words but became null after two presentations; in naming it was also initially strong but was merely reduced (although still substantial) after three repetitions. Mixed case words were recognized and named more slowly and tended to show stronger regularity effects. The results were consistent with the primary hypothesis that familiar word forms are read faster because they are processed at a larger grain-size, which requires fewer operations to achieve lexical selection. Results are discussed in terms of a neurobiological model of word recognition based on brain imaging studies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.812-814
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• 2015

In this letter, a distributed self-organized cell association scheme is proposed for heterogeneous cellular networks. In which each small cell uses a common self-organization strategy and takes its environment into account to establish its own cell association scheme. It is confirmed that the proposed cell association improves the user throughput and areal spectral efficiency compared to joint association.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.154-155
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• 2007

PRAM(Phase-Change RAM) is a promising memory that can solve the problem of conventional memory and has the nearly ideal memory characteristics. We reviewed the issues for high density PRAM integration. Writing current reduction is the most urgent problem for high density PRAM realization. So, we studied new constitution of $Ge_1Se_1Te_2$ chalcogenide material and presented the method of reducing the contact size between $Ge_1Se_1Te_2$ and electrode. A small-contact-area electrode is used primarily to supply current into and minimize heat loss from the chalcogenide. In this letter, we expect the method of reducing the contact size between $Ge_1Se_1Te_2$ and electrode to decrease writing current.

• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.59-62
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• 2019

Y2O3-MgO nanocomposites are promising materials for hypersonic infrared windows and domes due to their excellent midIR transmittance and mechanical properties. In this work, influence of SPS heating rate on the microstructure, IR transmittance, and mechanical properties of Y2O3-MgO nanocomposites was investigated. It was found that the average grain size decreases with a decreasing heating rate, which can be attributed to high defect concentration by rapid heating and deformation during densification. Also, the residual porosity decreases with a decreasing heating rate, which is ascribed to the enhancement of grain boundary diffusion by a large grain-boundary area (a small grain size). Consequently, high transmittance and hardness were attained by the low heating rate. On the other hand, the mechanical strength showed little difference with the heating rate change, which is somewhat different from the general knowledge on ceramics and will be discussed in this letter.

• Journal of the Korean Society of Costume
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• v.65 no.7
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• pp.32-46
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• 2015

Treasures patterns are simplified designs of vessels used in everyday life, which were symbols of luck. Treasures patterns on textiles are largely assorted into four groups: eight auspicious patterns of Buddhism, eight immortal patterns of Taoism, seven treasures patterns of King Chakravarti in the Buddhist Scriptures and normal treasures patterns. Among them normal treasures patterns are most commonly used. Records in the Joseon documents show these patterns as being composed of seven treasures patterns or eight treasures patterns. But observation of the actual relics show that these patterns ranged from four to ten patterns. Korean traditional textiles treasures patterns began to appear in Korea on the relics of the last of Goryeo period. They were used as sub-patterns among main patterns of dynamically rising cloud patterns with five heads. Treasures patterns in the early Joseon period were commonly used as sub-patterns, and cloud and treasures pattern were prime examples of this. In the 16th century, lotus vine pattern, small flower vine pattern, or small flower pattern were often used as main patterns and treasures patterns were regularly used as sub-patterns. The robe of the Great Monk of Seo San was unique, in that both main and sub patterns consisted of the treasures patterns. From the 17th century, treasures patterns began to be used as main patterns. For example, a relic with eight alternatively arranged treasures patterns were found. Though there were still some cases where the patterns were used as sub-patterns, they begin to appear bigger than the previous period and became similar to main patterns in size. In the 18th and 19th centuries, there were various cases where treasures patterns were combined with flowers, fruits, animals, and letter patterns and used as main patterns. And there are many different methods of representing and developing the patterns.