• ETRI Journal
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• v.35 no.5
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• pp.819-826
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• 2013

A class-D audio amplifier for a digital hearing aid is described. The class-D amplifier operates with a pulse-code modulated (PCM) digital input and consists of an interpolation filter, a digital sigma-delta modulator (SDM), and an analog SDM, along with an H-bridge power switch. The noise of the power switch is suppressed by feeding it back to the input of the analog SDM. The interpolation filter removes the unwanted image tones of the PCM input, improving the linearity and power efficiency. The class-D amplifier is implemented in a 0.13-${\mu}m$ CMOS process. The maximum output power delivered to the receiver (speaker) is 1.19 mW. The measured total harmonic distortion plus noise is 0.015%, and the dynamic range is 86.0 dB. The class-D amplifier consumes 304 ${\mu}W$ from a 1.2-V power supply.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.128-131
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• 2005

Structural Dynamics Modification (SDM) is a very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures. changing material properties and shape of structure. Among those of SDM technique, the method to change shape of structure has been mostly relied on engineer's experience and trial-and-error process which are very time consuming. In order to develop a systematic method to change structure shape, surface grooving technique is studied and successfully applied to HDD cover model. To check the effectiveness of this surface grooving technique, the grooved HDD cover design was manufactured using rapid prototyping and experimentally tested to prove the effectiveness of the grooving method as one of SDM techniques. And the modal strain energy and eigenvalue sensitivity method for choosing the initial starting point are compared.

• Proceedings of the ESK Conference
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• 1995.10a
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• pp.214-218
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• 1995

A lot of design guidelines have been proposed for menu-drive interfaces, but they are applicable only to the menus on ordinary CRT displays. Many hardware products, however, cannot employ large displays because of the cost and space limitations. Instead, a single-line display menu (SDM) is widely used, and the designers need useful guidelines applicable to the SDM. A focus is often placed upon the optimal menu structure, but only the standard menu structures, such as $64^{\1}, 8^{\2}, 4^{\3}, and 2^{\6}$, are tested for optimality. In many cases, however, ill defined or asymmetric structures are suggested as design alternatives. To determine the optimal menu structure, user performance should be obtained in terms of quantitative measures for each of the optional structures considered. Hence, a model is needed to provide a predicted value of user performance for a given menu structure. Although severaal models have been proposed for ordinary menus, none is available for the SDM yet. A performance model was developed in this study using the neural network approach. A The model developed in this study is capable of providing quantiative measures of human performance for any menu structures without conducting additional experiments, which will save much time and reduce the design cost.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.534-544
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• 1995

Many electronic products employ menu-driven interfaces for user-system dialogue. Unlike the software user interfaces, a small single-line display, such as a Liquid Crystal Display, is typically used to present menu items. Since the display can show only a single menu item at a time, more serious navigation problems are expected with single-line display menus(SDM). This study attempts to provide a set of unique guidelines for the design of the SDM based on empirical results. A human factors experiment was conducted to examine the effects of four design variables: menu structure, user experience, navigation aid, and number of targets. The usability of design alternatives was measured quantitatively in four different aspects, which were speed, accuracy, inefficiency of navigation, and subjective user preference. The analysis of variance was used to test the statistical effects of the design variables and their interaction effects. A set of design guidelines was drawn from the results which can be applied to the design of human-system interfaces of a wide variety of electronic consumer products using such displays. Since more generalized guidelines could be provided by constructing prediction models based on the empirical data, some powerful performance models are also required for the SDM. As a preliminary study, a survey was done on the performance models for ordinary computer menus.

• Journal of the Ergonomics Society of Korea
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• v.15 no.2
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• pp.157-163
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• 1996

A single line display menu (SDM) is widely used for the user interface of many electronic consumer products, and the designers need useful guidelines applicable to the SDM. In many studies on menus, major focus has been placed on the optimal menu structure, but only a few standard menu structures, such as $64^{1},8^{2},4^{3}$,and $2^{6}$ are usually tested for optimality. In many cases, however, ill defined or asymmetric structures are suggested as design alternatives. To determine the optimal menu structure, user performance should be obtained in terms of quantitative measures. Hence, a model is needed to provide a predicted value of user performance for a given menu structure. Altough several models have been proposed for ordinary menus, none is available for the SDM yet. To solve this problem a performance model was developed in this study using the neural network approach. This model is capable of providing quantitative measures of human performance for any menu structures without conducting additional experiments, which will save much time and reduce the design cost.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.355-364
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• 2002

The goal of this research is to reduce noise level of an outdoor unit of air conditioner by changing its dynamic characteristics using SDM (structural dynamics modification) technique. At first, the emitting noise was measured and analyzed. The measurement records show the most critical frequency components which influences on the noise level. Then it was tried to move the natural frequencies outside the critical frequency region by SDM. Since it is very difficult to get a reliable FE model of air conditioner, experimentally measured frequency response functions were used to derive sensitivities that are very important to obtain design changes. The positions of modification and the thickness of modifying structures were determined to improve the dynamic characteristics of air conditioner. The recommended design guideline to move its natural frequencies outside the targeting frequency range was obtained. Then in order to prove its effectiveness, the changed design was experimentally tested and found that the SDM result is very effective to reduce not only its vibration but also its emitting noise.

• YAKHAK HOEJI
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• v.15 no.2
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• pp.41-52
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• 1971

Cu(II) chelates of several sulfanilamide derivatives (Sulfa-Cu) were prepared and their effects on solubility, absorptivity in intestinal lumen, biding tendency with serum protein and erythrocytes, concentration in rabbit blood, and acetylation rate were studied in comparison with their free ligand forms. For solubility concerned, the partition coefficients of Sulfa-Cu are decreased as following order: Sulfadimethoxine Copper chelate (SDM-Cu), Sulfamethoxypyridazine Copper chelate (SD-Cu), Sulfamerazine Copper chelate (SM-Cu), Sulfaisoxazole Copper chelate (SIX-Cu). The partition coefficients of SDM-Cu and ST-Cu were much greater than those of ligands. this phenomenone acounts for the rapid absorption of SDM-Cu and ST-Cu in the rat small intestine (in situ). The Sulfa-Cu were absorbed at the intestinal lumen of a rat in the rate of first order and there was no difference between long acting sulfa drugs and their Cu0chelates in biological half lives. In binding experiments, sulfa-Cu binded with serum protein in lower ratio than their ligands except SIX-Cu. On other hand, acetylation rates of sulfa-Cu were higher than those of free sulfa drugs and the acetylation rate were higher than those of free sulfa drugs and powder. In a experiment on Sulfa-Cu concentration in rabbit blood, the half lives of SD-Cu, SIX-cu, ST-Cu, and SM-Cu were longer than those of their ligands. Above all, the half life of SD-Cu appeared to be approximately 3.5 times logner than that of corresponding ligand, SD. When absorption of sulfa drugs or sulfa-Cu at the small intestinal lumen of a rat and the concentration in rabbit blood after absorption were compared, it was found that there was not always conrrelated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.434-441
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• 2015

To develop dough methods for improving bread making properties of Korean wheat flour, straight dough methods (SDM) and dough and sponge methods (DSM) were applied. The bread making properties such as weight of bread, specific volume, baking loss, crumb color, and texture were analyzed. In comparison of flour properties between Korean wheat flour and imported wheat flour by Farinograph, Korean wheat flour showed less gluten network form ability than imported wheat flour. The dough making method affected bread quality such as weight of bread, specific volume, and baking loss. SDM had a more desirable effect on bread quality. Crumb color was lighter in bread made with Korean wheat flour compared to imported wheat flour, whereas dough making method did not affect crumb color. In consumer acceptance analysis, bread made by DSM showed higher consumer acceptance than that made by SDM. Regarding physicochemical changes during storage, bread made by SDM using Korean wheat flour showed higher chewiness, brittleness, and hardness than that made by imported wheat flour. However, bread made by DSM showed similar chewiness as bread made by SDM using imported wheat flour. The bread making properties of bread made by DSM is improved versus that of bread made with Korean wheat flour.

• 건축구조
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• v.20 no.1
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• pp.60-63
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• 2013

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.6
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• pp.678-685
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• 2012

The objective of this study is to monitor the health status of harbor caissons which have potential foundation damage. To obtain the objective, the following approaches are performed. Firstly, a structural damage monitoring(SDM) method is designed for interlocked multiple-caisson structures. The SDM method utilizes the change in modal strain energy to monitor the foundation damage in a target caisson unit. Secondly, a finite element model of a caisson system which consists of three caisson units is established to verify the feasibility of the proposed method. In the finite element simulation, the caisson units are constrained each other by shear-key connections. The health status of the caisson system against various levels of foundation damage is monitored by measuring relative modal displacements between the adjacent caissons.