• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.433-439
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• 2023

본 연구에서는 높은 역학적, 내구적 성능이 확보된 UHPC(Ultra High Performance Concrete) 배합을 기반으로 보수재료를 개발하기 위해 일반 콘크리트 보수면을 대상으로 부착성능을 평가하였다. 보수 대상 모체의 표면의 거칠기와 습윤 상태 그리고 보수재료 배합에 폴리머 혼입 및 PP, PVA 섬유 사용을 고려하여 총 10가지 시험 변수를 적용하였다. 폴리머를 혼입함에 따라 큰 폭의 강도 저하가 발생하였으며 이는 워커빌리티 조정을 위해 추가로 사용한 감수제의 영향으로 사료된다. 또한 플라스틱 계열 섬유를 혼입함에 따라 플로우가 최대 13.8 % 감소하였다. 부착면의 상태를 고려한 보수재료의 부착 강도 평가 결과 UHPC 기반 보수재료를 사용하는 경우 보수 대상 모체의 표면이 건전하다면 별도의 면 처리 작업 없이 높은 부착성능을 확보할 수 있는 것으로 판단된다. 또한 UHPC 기반 보수재료는 부착면의 습윤하더라도 높은 부착성능을 나타내었다. 추후 UHPC 기반 보수재료의 개발을 위해 숏크리트 적용과 구배 타설에 대한 연구가 진행될 예정이며 콘크리트 구조 보수재료로써의 경제성과 성능 확보를 위해 지속적인 보수재료 배합 개선이 수행될 계획이다.

• 정신신체의학
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• 제5권1호
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• pp.89-96
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• 1997

SLE 환자들에서 인지기능의 장애가 있는지를 알아보기 위해서 신경정신과적 병력이 없는 내과 외래 SLE 환자 20명과 정상 대조군 20명을 대상으로 전산화 신경인지기능 검사인 Vienna test system을 시행하고 이를 인지기능에 영향을 미칠 수 있는 임상 변인들과의 연관성을 분석하여 다음과 같은 결과를 얻었다. 1) SLE 환자군과 정상 대조군의 신경인지기능 검사의 각 항목 비교 인식력 검사항목에서 SLE 환자군은 정상 대조군에 비해 정확하게 응답한 반응수가 적었으며 '예'와 '아니오' 중 '아니오'를 정확하게 반응한 수도 적었다. 또한 '예'와 '아니오'에 대해 각각 정확한 반응을 하는 평균 반응시간이 길었으며 검사소요 시간도 길었다. 주의력 검사항목에서는 SLE 환자군이 정상 대조군에 비해 정확하게 응답한 반응수가 적었고, 평균 반응시간이 길었다. 그러나, corsi단기 기억력 검사항목에서는 시각적 단기 기억력 범위와 정확하게 맞춘 총 응답수에서 두군 간에 유의한 차이가 없었다. 표준도형 지능검사항목에서 SLE 환자군은 정상 대조군에 비해 정확하게 응답한 반응수가 적었다. 신경행동학적 인지상태 검사중 기억력 항목에서 SLE 환자군은 정상 대조군에 비해 유의하게 낮은 점수를 보였다. 2) 신경인지기능의 각 항목과 환자군의 연령, 교육연한, SLE 질환 활성도(SLE Disease Activity Index), 우울 증상의 정도, 항 ds-DNA항체. 보체 C3/C4, 스테로이드의 용량 등의 임상 변인들과의 상관관계를 비교하였을 때 통계적으로 유의하지 않았다. 이상의 결과에서 질환 활성도가 낮은 SLE환자들은 과거 신경정신과적 증상의 병력이 없고 병의 이환 기간이 비교적 짧음에도 불구하고 인지기능의 장애를 나타내었다. 그리고 이는 기타 장기의 침범으로 인한 비특이적 영향이 아닌 중추신경계의 침범에 의한 것으로 보이며 우울정도나 스테로이드 용량에 영향을 받지 않는 것으로 생각된다.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.816-821
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• 2017

하수 및 폐수 내 고농도의 인 및 부유물질 제어를 위해 개발한 일체형 완속교반/침전 그물망 압착식 섬유여과시스템을 이용하여 하수처리장의 반류수 내 부유성 고형물 및 인 처리에 적용했을 경우에 따른 성능을 검토하고자 하였다. 6가지 Mode로 실험을 하였으며, 16.7, 33.3, 41.7 및 50.0 ton/day 유량과 Al/P 몰비 2~4의 조건에서 실험을 행하였다. 응집제를 주입하였을 경우에 모두 높은 총인(T-P) 제거 효율을 보였지만 연속운전시간이 7.8 min~11.4 min으로 짧아지는 단점이 생겼다. 이를 극복하기 위해 일체형 완속교반/침전 그물망 압착식 섬유여과시스템을 응집/급속교반/공기주입/완속교반/침전공정 및 여과공정으로 진행 시 연속운전시간이 88.2 min으로 다른 모드로 운전한 결과에 비해 8~11.3배 정도 증가하였다. 역세수량율도 5.4%로 매우 낮게 나타남에 따라 이 공정이 가장 효율적인 처리방안으로 평가되었다.

• 방송공학회논문지
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• 제21권6호
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• pp.929-943
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• 2016

본 논문에서는 인지 화질을 고려하기 위해 S-JND 모델 기반의 율 제어 알고리즘을 제안한다. 제안하는 율 제어 알고리즘은 인간이 가지는 시각 시스템의 특징을 반영하기 위하여 시각적 민감도와 시각적 관심도를 동시에 반영할 수 있도록 제작된 S-JND (Saliency-Just Noticeable Difference) 모델을 사용한다. 율 제어 알고리즘을 통해 비트를 분배하는 과정에서 픽쳐 내에 존재하는 각 CTU (Coding Tree Unit)가 가지는 S-JND threshold를 구한다. 각 CTU의 threshold는 적응적으로 적절한 비트를 분배하는데 사용되고, 따라서 제안하는 비트 분배 모델은 인지 화질을 향상 시킬 수 있다. 제안하는 방법의 성능 검증을 위해서 제안하는 방법을 HM 16.9에 구현하였으며, CTC (Common Test Condition) RA (Random Access), Low-delay B와 Low-delay P의 경우에 Class B와 Class C 영상들에 대해 실험 하였다. 실험 결과, 제안하는 방법은 기존 율 제어 알고리즘 대비 평균 2.3%의 비트율이 감소했고 BD-PSNR은 약 0.07dB 향상이 있었으며 비트 정확도 또한 0.06% 정도 증가하였다. DSCQS (Double Stimulus Continuous Quality Scale) 방법으로 측정한 결과, 제안하는 방법은 기존 방법 대비 0.03 MOS (Mean Opinion Score) 향상을 보였다.

• Asia pacific journal of information systems
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• 제18권4호
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• pp.57-81
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• 2008

Knowledge is an essential strategic weapon for sustaining competitive advantage and is the key determinant for organizational growth. When knowledge is shared and disseminated throughout the organization, it increases an organization's value by providing the ability to respond to new and unusual situations. The growing importance of knowledge as a critical resource has forced executives to pay attention to their organizational knowledge. Organizations are increasingly undertaking knowledge management initiatives and making significant investments. Knowledge sourcing is considered as the first important step in effective knowledge management. Most firms continue to make an effort to realize the benefits of knowledge management by using various knowledge sources effectively. Appropriate knowledge sourcing strategies enable organizations to create, acquire, and access knowledge in a timely manner by reducing search and transfer costs, which result in better firm performance. In response, the knowledge management literature has devoted substantial attention to the analysis of knowledge sourcing strategies. Many studies have categorized knowledge sourcing strategies into intemal- and external-oriented. Internal-oriented sourcing strategy attempts to increase firm performance by integrating knowledge within the boundary of the firm. On the contrary, external-oriented strategy attempts to bring knowledge in from outside sources via either acquisition or imitation, and then to transfer that knowledge across to the organization. However, the extant literature on knowledge sourcing strategies focuses primarily on large organizations. Although many studies have clearly highlighted major differences between large and small firms and the need to adopt different strategies for different firm sizes, scant attention has been given to analyzing how knowledge sourcing strategies affect firm performance in small firms and what are the differences between small and large firms in the patterns of knowledge sourcing strategies adoption. This study attempts to advance the current literature by examining the impact of knowledge sourcing strategies on small firm performance from a holistic perspective. By drawing on knowledge based theory from organization science and complementarity theory from the economics literature, this paper is motivated by the following questions: (1) what are the adoption patterns of different knowledge sourcing strategies in small firms (i,e., what sourcing strategies should be adopted and which sourcing strategies work well together in small firms)?; and (2) what are the performance implications of these adoption patterns? In order to answer the questions, this study developed three hypotheses. First hypothesis based on knowledge based theory is that internal-oriented knowledge sourcing is positively associated with small firm performance. Second hypothesis developed on the basis of knowledge based theory is that external-oriented knowledge sourcing is positively associated with small firm performance. The third one based on complementarity theory is that pursuing both internal- and external-oriented knowledge sourcing simultaneously is negatively or less positively associated with small firm performance. As a sampling frame, 700 firms were identified from the Annual Corporation Report in Korea. Survey questionnaires were mailed to owners or executives who were most erudite about the firm s knowledge sourcing strategies and performance. A total of 188 companies replied, yielding a response rate of 26.8%. Due to incomplete data, 12 responses were eliminated, leaving 176 responses for the final analysis. Since all independent variables were measured using continuous variables, supermodularity function was used to test the hypotheses based on the cross partial derivative of payoff function. The results indicated no significant impact of internal-oriented sourcing strategies while positive impact of external-oriented sourcing strategy on small firm performance. This intriguing result could be explained on the basis of various resource and capital constraints of small firms. Small firms typically have restricted financial and human resources. They do not have enough assets to always develop knowledge internally. Another possible explanation is competency traps or core rigidities. Building up a knowledge base based on internal knowledge creates core competences, but at the same time, excessive internal focused knowledge exploration leads to behaviors blind to other knowledge. Interestingly, this study found that Internal- and external-oriented knowledge sourcing strategies had a substitutive relationship, which was inconsistent with previous studies that suggested complementary relationship between them. This result might be explained using organizational identification theory. Internal organizational members may perceive external knowledge as a threat, and tend to ignore knowledge from external sources because they prefer to maintain their own knowledge, legitimacy, and homogeneous attitudes. Therefore, integrating knowledge from internal and external sources might not be effective, resulting in failure of improvements of firm performance. Another possible explanation is small firms resource and capital constraints and lack of management expertise and absorptive capacity. Although the integration of different knowledge sources is critical, high levels of knowledge sourcing in many areas are quite expensive and so are often unrealistic for small enterprises. This study provides several implications for research as well as practice. First this study extends the existing knowledge by examining the substitutability (and complementarity) of knowledge sourcing strategies. Most prior studies have tended to investigate the independent effects of these strategies on performance without considering their combined impacts. Furthermore, this study tests complementarity based on the productivity approach that has been considered as a definitive test method for complementarity. Second, this study sheds new light on knowledge management research by identifying the relationship between knowledge sourcing strategies and small firm performance. Most current literature has insisted complementary relationship between knowledge sourcing strategies on the basis of data from large firms. Contrary to the conventional wisdom, this study identifies substitutive relationship between knowledge sourcing strategies using data from small firms. Third, implications for practice highlight that managers of small firms should focus on knowledge sourcing from external-oriented strategies. Moreover, adoption of both sourcing strategies simultaneousiy impedes small firm performance.

• 정보처리학회논문지B
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• 제10B권2호
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• pp.169-178
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• 2003

This study outlines two viewpoints the classification of phone likely unit (PLU) which is the foundation of korean large vocabulary speech recognition, and the effectiveness of Chiljongseong (7 Final Consonants) and Paljogseong (8 Final Consonants) of the korean language. The phone likely classifies the phoneme phonetically according to the location of and method of articulation, and about 50 phone-likely units are utilized in korean speech recognition. In this study auditory phonetical knowledge was applied to the classification of phone likely unit to present 45 phone likely unit. The vowels 'ㅔ, ㅐ'were classified as phone-likely of (ee) ; 'ㅒ, ㅖ' as [ye] ; and 'ㅚ, ㅙ, ㅞ' as [we]. Secondly, the Chiljongseong System of the draft for unified spelling system which is currently in use and the Paljongseonggajokyong of Korean script haerye were illustrated. The question on whether the phonetic value on 'ㄷ' and 'ㅅ' among the phonemes used in the final consonant of the korean fan guage is the same has been argued in the academic world for a long time. In this study, the transition stages of Korean consonants were investigated, and Ciljonseeng and Paljongseonggajokyong were utilized in speech recognition, and its effectiveness was verified. The experiment was divided into isolated word recognition and speech recognition, and in order to conduct the experiment PBW452 was used to test the isolated word recognition. The experiment was conducted on about 50 men and women - divided into 5 groups - and they vocalized 50 words each. As for the continuous speech recognition experiment to be utilized in the materialized stock exchange system, the sentence corpus of 71 stock exchange sentences and speech corpus vocalizing the sentences were collected and used 5 men and women each vocalized a sentence twice. As the result of the experiment, when the Paljongseonggajokyong was used as the consonant, the recognition performance elevated by an average of about 1.45% : and when phone likely unit with Paljongseonggajokyong and auditory phonetic applied simultaneously, was applied, the rate of recognition increased by an average of 1.5% to 2.02%. In the continuous speech recognition experiment, the recognition performance elevated by an average of about 1% to 2% than when the existing 49 or 56 phone likely units were utilized.

• Computers and Concrete
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• 제20권2호
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• pp.205-214
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• 2017

The Hydraulically driven test system and ${\Phi}100mm$ split Hopkinson pressure bar(SHPB) test device were employed to research the quasi-static and dynamic mechanical properties of concrete specimens which has been immersed for 60 days in sodium sulfate (group S1) and sodium chloride (group S2) solution, the evolution of their mass during corrosive period was explored at the same time, and the mechanism of performances lost was analyzed from the microscopic level by using scanning electron microscope. Results of the experimental indicated that: their law of mass both presents the trend of continuous rising during corrosive period, and it increases rapidly on the early days, the mass growth of group S1 and group S2 in first 7 days are 76.78% and 82.82% of their total increment respectively; during the corrosive period, the quasi-static compressive strength of specimens in two groups are significantly decreased, both of which present the trend of increase first and then decrease, the maximum growth rate of group S1 and group S2 are 7.52% and 12.71% respectively, but they are only 76.23% and 82.84% of specimens which under normal environment (group N) on day 60; after immersed for 60 days, there were different decrease to dynamic compressive strength and specific energy absorption, and so as their strain rate sensitivities. So the high salinity environment has a significant effect of weaken the quasi-static and dynamic mechanical performance of concrete.

• 한국자동차공학회논문집
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• 제18권1호
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• pp.14-22
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• 2010

Hybrid Electronic Vehicle (HEV) is one of the solutions of high oil price and environment problem. Recently, study of HEV is important for automobile industry. However HEV has a lot of components and there are many cases for assembling, it's impossible to test results from assembling by using real vehicles. To solve this problem, hybrid system simulator is required. The purpose of this study is to develop and optimize of engine module for hybrid system simulator. The commercial 1-D engine simulation program, WAVE is used to get the engine capacity and performance data and 1-D simulation model of base engine is compared with engine experiment results. Using the data, the engine module is developed based on the MATLAB Simulink. There are blocks of base engine, Single-CVVT engine and Dual-CVVT engine. The effect of acceleration and deceleration is applied to each engine block. In addition, the control and processing logics for CIS technology are developed. Finally the simulator operates FTP-72 mode test.

• 한국항공우주학회지
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• 제41권11호
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• pp.908-914
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• 2013

본 연구에서는 소형 태양광 무인항공기를 개발하여 비행시험을 수행하였다. 태양광 무인기는 날개에 설치된 태양전지로부터 전력을 생산하고, 생산된 전력의 일부를 비행동력으로 사용하며, 나머지를 일몰 후 비행을 위해 배터리에 저장을 한다. 태양광 무인항공기는 공기역학적으로 매우 효율이 높아야 하며, 구조적으로 경량이면서 고강도를 가져야 한다. 또한, 태양광 무인기의 전기추진시스템과 태양광 발전시스템도 높은 효율을 가져야 한다. 본 연구에서는 12시간 이상의 연속 비행을 위한 태양광 무인항공기 및 태양광 시스템을 개발하고, 그 성능을 파악하기 위해 비행시험을 수행하였다. 가을과 겨울철의 비행시험 결과 본 연구에서 개발한 태양광 무인항공기의 사계절 모두 12시간 이상의 연속비행이 가능함을 알 수 있었다.

• 생물정신의학
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• 제19권1호
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• pp.45-52
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• 2012

Objectives : This study was designed to investigate the usability of IVA + Plus (Continuous Performance Test) and Neuro-Guide [Quantitative electroencephalography (EEG) normative database] as an auxiliary diagnostic tools for attention-deficit hyperactivity disorder (ADHD). Methods : The scores of IVA + Plus and resting EEG were obtained from 34 elementary school-aged children. Also, the Korean ADHD Rating Scale (K-ARS) and the Diagnostic Interview Schedule for Children version IV (DISC-IV) was done for the parent of them. From the result of the DISC-IV, we divided them into three groups, ADHD Not Otherwise Specified (NOS), and Normal Control (NC). Using NeuroGuide, the z-scores of relative power for delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), and beta (12-25 Hz) were calculated. Then the correlation and variance analysis were done to investigate the differences between three groups. Results : The scores of IVA + Plus were negatively correlated with the K-ARS. IVA + Plus have successfully discriminated the ADHD from NC and NOS. The z-scores of relative power of delta and theta were positively correlated with the K-ARS. The z-scores of relative power of alpha and beta were negatively correlated with the K-ARS. Conclusions : The IVA + Plus and NeuroGuide QEEG test are expected to be used as the valuable tools for diagnosing ADHD accurately.