• 한국전자통신학회논문지
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• 제10권5호
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• pp.565-570
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• 2015

확산 스펙트럼 통신은 낮은 도청확률과 작은 잡음 채널의 영향 때문에 많은 시스템에서 사용이 증가하고 있다. 기존의 디지털 확산 스펙트럼 시스템의 한계 중 하나는 동기 코드 확산에 대한 필요성이다. 카오스 통신 시스템은 동기 없이 구현 할 수 있고 보안성도 우수하며 간단한 송수신기 구조로 디지털 확산 스펙트럼 통신에 많이 사용하고 있다. 본 논문에서는 카오스 신호를 디지털 통신시스템에 사용하기 위해 디지털 변복조의 반송파 대신 사용하였으며 여러 가지의 카오스 변조 방식들 중에서 차동 CSK(Differential Chaos Shift Keying) 사용한다. DCSK 복조기는 카오스 신호 위상을 복구 할 필요 없이 데이터를 감지하기 때문에 효율적이다. 또한 Matlab/Simulink를 이용하여 DCSK 변조기 및 복조기의 설계하고 성능을 분석하고 송신신호의 수신 신호를 비교하여 송수신 신호가 같은 것을 확인하고 확산 인자에 따른 BER의 성능을 평가한다.

• 한국지진공학회논문집
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• 제12권5호
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• pp.31-38
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• 2008

최근 구조물의 지진해석에서 시간이력 지진해석의 필요성이 증대되고 있는데, 시간이력해석을 위해서는 최소7개의 지진기록을 사용하도록 IBC2003, ASCE와 KBC2005의 내진설계 기준에서 요구하고 있다. 시간이력 지진해석을 위해 지진기록의 선정은 주어진 대지 조건에 따른 설계스펙트럼을 만족하도록 시간이력 지진기록을 설계 지반조건과 유사한 지반에서 계측된 지진기록들 중에서 선정하거나 설계스펙트럼을 만족하는 인공지진기록을 생성하여 사용할 수 있지만, 이 연구에서는 절충적 방법으로 태평양지진연구센터(PEER) 데이터베이스에서 암반 지진기록으로 알려진 50개 계측지진기록을 이용하여 7개 인공 시간이력 지진기록을 생성하였다. 일차 조정계수를 곱한 지진응답스펙트럼이 목표설계스펙트럼에 최적합한 7개 지진기록을 선정하고, SRSS 평균값이 목표설계스펙트럼과 최소의 오차를 갖게 하는 최적합화법으로 구한 조정계수를 선정된 각 지진기록에 곱하여 7개 인공 시간이력 지진기록군을 생성하였다.

• 한국의상디자인학회지
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• 제20권1호
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• pp.49-59
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• 2018

The purpose of this research is to study the semantic characteristics of men's cosmetics brand names by analyzing 51 brand names in the domestic market, so as to find ways to develop strategic brand names. In order to investigate this area, the study looked at the Interbrand Company's Name Spectrum, and the results are as follows. The men's cosmetics brand names turned out to be freestanding brand names, descriptive brand names, and associative brand names, in that order. The freestanding brand names were found to be the initial combinations of the words that have the desired benefits in the concepts of the pertinent brands; in other words, coined brand names that were made by synthesizing words such as nice men, naturalism, eco-friendly plant-derived materials and ideal skin. Associative brand names are generally used to express the effect of enhancing brand awareness by considering the phonetic image of the word or prompting a masculine and favorable image. Descriptive brand names use language symbols such as men, homme, man, monsieur and gentle to represent specific business and product categories for men, and also use stem, plant, flower, skin, beauty, moisturizing, tosowoong and so on to provide the properties and beneficial information related to the products. In conclusion, the men's cosmetics brand names embody an important factor that symbolizes the concepts, functions or features of the brand, and there is a need for men's cosmetic brands to develop more unique and distinctive brand names to promote their brand names as constitutional factors that can build brand power and strengthen brand image.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.3-6
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• 2000

Antimicrobial resistance has been a well-recognized problem ever since the introduction of penicillin into clinical use. History of antimicrobial development can be categorized based on the major antibiotics that had been developed against emerging resistant $pathogens^1$. In the first period from 1940 to 1960, penicillin was a dominating antibiotic called as a "magic bullet", although S.aureus armed with penicillinase led antimicrobial era to the second period in 1960s and 1970s. The second stage was characterized by broad-spectrum penicillins and early generation cephalosporins. During this period, nosocomial infections due to gram-negative bacilli became more prevalent, while those caused by S.aureus declined. A variety of new antimicrobial agents with distinct mechanism of action including new generation cephalosporins, monobactams, carbapenems, ${\beta}$-lactamase inhibitors, and quinolones characterized the third period from 1980s to 1990s. However, extensive use of wide variety of antibiotics in the community and hospitals has fueled the crisis in emerging antimicrobial resistance. Newly appeared drug-resistant Streptococcus pneumoniae (DRSP), vancomycin-resistant enterococci (VRE), extended-spectrum ${\beta}$-lactamase-producing Klebsiella, and VRSA have posed a serious threat in many parts of the world. Given the recent epidemiology of antimicrobial resistance and its clinical impact, there is no greater challenge related to emerging infections than the emergence of antibiotic resistance. Problems of antimicrobial resistance can be amplified by the fact that resistant clones or genes can spread within or between the species as well as to geographically distant areas which leads to a global concern$^2$. Antimicrobial resistance is primarily generated and promoted by increased use of antimicrobial agents. Unfortunately, as many as 50 % of prescriptions for antibiotics are reported to be inappropriate$^3$. Injudicious use of antibiotics even for viral upper respiratory infections is a universal phenomenon in every part of the world. The use of large quantities of antibiotics in the animal health industry and farming is another major factor contributing to selection of antibiotic resistance. In addition to these background factors, the tremendous increase in the immunocompromised hosts, popular use of invasive medical interventions, and increase in travel and mixing of human populations are contributing to the resurgence and spread of antimicrobial resistance$^4$. Antimicrobial resistance has critical impact on modem medicine both in clinical and economic aspect. Patients with previously treatable infections may have fatal outcome due to therapeutic failure that is unusual event no more. The potential economic impact of antimicrobial resistance is actually uncountable. With the increase in the problems of resistant organisms in the 21st century, however, additional health care costs for this problem must be enormously increasing.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.291-298
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• 2003

The resonant column testing is a laboratory testing method to determine the shear modulus and the material damping factor of soils. The method has been widely used for many applications and its importance has been increased. Since the establishment of the testing method in 1963, the low-technology electronic devices for testing and data acquisition have limited the measurement to the amplitude of the linear spectrum. The limitations of the testing method were also attributed to the assumption of the linear-elastic material in the theory of the resonant column testing and to the use of the wave equation for the dynamic response of the specimen. For the better theoretical formulation of the resonant column testing, this study derived the equation of motion and provided its solution. This study also proposed the improved data reduction and analysis method for the resonant column testing, based on the advanced data acquisition system and the proposed theoretical solution for the resonant column testing system. For the verification of the proposed data reduction and analysis method, the numerical simulation of the resonant column testing was performed by the finite element analysis. Also, a series of resonant column testing were peformed for Joomunjin sand, which verified the feasibility, of the proposed method and showed the limitations of the conventional data reduction and analysis method.

• Coupled systems mechanics
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• 제12권4호
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• pp.315-335
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• 2023

The building sector has seen a huge increase in the use of lightweight concrete recently, which might result in saving in both cost and time. As a result, the study has been done on various types of concrete, including lightweight (LC), heavyweight (HC), and ordinary concrete (OC), to understand how they react to earthquake loads. The comparisons between their responses have also been taken into account in order to acquire the optimal reaction for various materials in building work. The findings demonstrate that LWC building models are more earthquake-resistant than the other varieties due to the reduction in building weight which can be a curial factor in the resistance of earthquake forces. Another crucial factor that was taken into study is the combination of various types of concrete [HC, LC, and OC] in the structural components. On the other hand, the bending moments and shear forces of LC had reduced to 17% and 19%, respectively, when compared to OC. Otherwise, the bending moment and shear force demand responses in the HC model reach their maximum values by more than 34% compared to the reference model OC. In addition, the results show that the LCC-OCR (light concrete column and ordinary concrete roof) and OCC-LCR (ordinary concrete for the column and light concrete for the roof) models' responses have fewer values than the other types.

• 대한음성학회지:말소리
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• 제57호
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• pp.153-164
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• 2006

The MMSE-STSA based speech enhancement algorithm is widely used as a preprocessing for noise robust speech recognition. It weighs the gain of each spectral bin of the noisy speech using the estimate of noise and signal power spectrum. In this paper, we investigate the influence of parameters used to estimate the speech signal and noise power in MMSE-STSA upon the recognition performance of noisy speech. For experiments, we use the Aurora2 DB which contains noisy speech with subway, babble, car, and exhibition noises. The HTK-based continuous HMM system is constructed for recognition experiments. Experimental results are presented and discussed with our findings.

• 말소리와 음성과학
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• 제7권1호
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• pp.125-131
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• 2015

The current study explores whether speaker variability in the fronted articulations of Seoul Korean affricates can be explained by cognitive differences measured by individual autistic traits. The goal was to explore Yu's (2010; 2013) proposal that individual differences in cognitive style can be an important factor in speakers' use of sound variants. The spectral peak frequencies (SPF) of affricates relative to those of fricatives, reported in Kong et al. (2014), were used to acoustically represent the relative degree of anterior place of constriction. When these individual SPFs were related to the scores of Autistic-Spectrum Quotients (Baron-Cohen et al., 2001), a correlation was found for the male speakers, but not for the female speakers, such that speakers of more anterior affricate productions scored low in AQs. Discussion is made with respect to how these findings are in line with Yu's proposal.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2564-2569
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• 2021

The neutronic analysis of Helium Cooled Ceramic Reflector (HCCR) breeding blankets has been performed using the 3D Monte Carlo code MCNPX and ENDF nuclear data library. This study aims to reduce ⁶Li percentage in the breeder zones as much as possible ensuring tritium self-sufficiency. This work is devoted to investigating the effect of ⁶Li percentage on the HCCR breeding blanket's neutronic parameters, such as neutron flux and spectrum, Tritium Breeding Ratio (TBR), nuclear power density, and energy multiplication factor. In the ceramic breeders at the saturated thickness, increasing the enrichment of ⁶Li reduces its share in the tritium production. Therefore, ceramic breeders typically use lower enriched Li from 30% to 60%. The investigation of neutronic analysis in the suggested geometry shows that using 60% ⁶Li in Li₂TiO₃ can yield acceptable TBR and energy deposition results, which would be economically feasible.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1021-1023
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• 2003

Atmospheric water vapor is a key variable in numerical weather prediction (NWP) models, but it is a crucial factor to limit the accuracy of high-precision GPS positioning technique. For both issues, knowledge about the amount of water vapor is extremely important. In this study, we perform a simulation study to utilize GPS signals through a developed tomographic scheme to retrieve 3D structure of atmospheric wet refractivity, which may be assimilated into NWP models for advancing forecasting or position calculation for improving GPS positioning accuracy. For the purpose of knowing the absolute accuracy of the developed tomographic method, a well-defined temporal and spatial varying state of atmospheric profile is utilized. Under such circumstance, several factors that may influence the retrievals can be easily examined and their impacts may be clearly quantified. They include the values of the positional dilution of precision (PDOP) factors of the GPS signals, ... etc. Based upon the use of a variety spectrum of adjustable factors, many interesting findings are obtained. For example, the more is the number of the observed GPS signals the better becomes the retrievals as expected. Also, the smaller is the PDOP value the better becomes the retrievals.