• 제목/요약/키워드: Instrument system

검색결과 1,595건 처리시간 0.027초

보리종실 성분분석을 위한 근적외선분광광도계의 이용방법 (Use of Near Infrared Reflectance Spectroscopy for Determination of Grain Components in Barley)

  • 김병주;박의호;서형수
    • 한국작물학회지
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    • 제40권6호
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    • pp.716-722
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    • 1995
  • 겉보리 품질에서 중요한 전분, $eta$-glucan, 단백질 및 회분을 근적외선분광분석법을 이용하여 신속하고 정확하게 분석할 수 있다면 양질의 겉보리 품종육성에 있어 선발효율을 높일 수 있을 것이다. 이러한 목적으로 겉보리 34계통을 공시하여 근적외선 분광광도계 Neotec 102를 이용한 근적외 스펙트럼과 각각의 화학분석치간의 중회귀분석에 의해 검량식을 작성하고 각 검량식별 측정 정확성을 분석한 결과는 다음과 같다. 1. 전분함량 분석시 2272/2078/2053/2055nm의 4개 파장으로 구성된 검량식이 추정치 표준오차(SEP)가 2.75, 상관계수가 0.932로 측정 정확성이 높았다 2. $\beta$-glucan 함량분석은 2276/2086nm의 2개 파장으로 구성된 검량식에서 추정치 표준오차(SEP)가 0.643, 상관계수가 0.588을 나타내 유의성은 인정되지 않았으나 본 실험에 사용된 근적외선 분광광도계 파장영역이 넓은 기기를 사용한다면 분석은 가능할 것으로 생각되었다. 3. 단백질은 1932/2242/2110nm의 3개 파장으로 구성된 검량식의 추정치 표준오차(SEP)가 0.257로 낮았고, 상관계수가 0.984로 측정 정확성이 매우 높게 나타났다. 4. 회분은 2160/1943/1941nm의 3개 파장으로 구성된 검량식을 이용하여 NIRS로 분석가능할 것으로 판단되었다.

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질량 분석기의 원형 모델 개발 (Development of a Prototype Mass Spectrometer)

  • 이진근;이남석;강성원;김선태;장규하;이유;홍익선;최정림;민경욱;정종일
    • 우주기술과 응용
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    • 제3권1호
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    • pp.86-99
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    • 2023
  • 질량분석기는 태양계와 생명의 기원을 밝히기 위한 필수 과학 장비로서, 달/행성/소행성/혜성 등의 대기 및 지표에 존재하는 중성 원소와 이온에 대한 정보를 파악하기 위해 1970년대 초반부터 우주 탐사에 활용되어 왔다. 제4차 우주개발진흥 기본계획(2023-2027)에 따르면 우리나라는 2032년에 달 착륙을 2045년에는 화성 착륙을 성공하는 것을 핵심 목표로 삼고 무인 탐사를 위한 능력을 확보하는 데 기술개발의 역점을 두기로 하였다. 따라서 우주 탐사의 과학적 목표 달성을 위한 가장 기본적인 장비이지만 국내 우주탐사에서 한번도 시도되지 않았던 질량분석기의 국내 개발은 필수적이라고 할 수 있다. 본 논문에서는 국내에서 개발된 사중극자 질량분석기의 원리와 원형 모델 및 성능에 대해 소개하고 향후 발전 방향에 대해 논의하고자 한다.

A Fundamental Study on Mode of Operation for Maritime Autonomous Surface Ship(MASS) - Based on review of IMCA M 220

  • Jeong-Min Kim;HyeRi Park
    • 한국컴퓨터정보학회논문지
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    • 제28권5호
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    • pp.163-170
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    • 2023
  • 제4차 산업혁명의 가속화에 따라 해운산업에서는 자율운항선박(MASS)의 기술 개발 및 발전이 이루어지고 있으며, 이에 따른 국제 규정의 개발 역시 가속화되고 있다. 특히 IMO 해사안전위원회(MSC) 105차 회의에서는 회원 당사국 간 비강제적 자율운항선박 규정(MASS Code) 개발을 위한 로드맵을 수립하고 본격적으로 규정 개발에 착수하였다. 다수의 국가가 MASS Code 개발 작업에 적극적으로 참여하고 있으며, MASS Code에서 MASS 기능에 대한 상세한 요구사항에 대한 규정 개발 작업이 진행중이다. 특히, 자율운항선박의 자율도와 관련하여 "운항 모드(Mode of Operation)" 개념이 처음으로 언급되었으며, 2023년 4월에 개최될 IMO 자율운항선박 공동작업반(MASS JWG) 회의부터 이 운항 모드에 대한 논의가 진행될 것으로 예상된다. "운항 모드" 개념은 MASS 및 MASS 기능에 대한 설명과 더불어, MASS Code 개발을 위해 지속되어 논의될 것이다. 이 논문은 운항 모드 설정에 대한 기초연구를 수행하기 위해 운항 모드에 대한 지침을 제공하는 IMCA M 220 문서의 내용을 검토한다.

항공기 기내 청소노동자의 분진, 초미세먼지(PM2.5) 및 블랙카본 노출수준 평가 (Exposure Assessment of Dust, Ultra Fine Dust(Particulate Matter 2.5, PM2.5) and Black Carbon among Aircraft Cabin Cleaners)

  • 박현희;김세동;김성호;박승현
    • 한국산업보건학회지
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    • 제33권2호
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    • pp.171-187
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    • 2023
  • Objectives: Aircraft cabin cleaning work is characterized by being performed within a limited time in a narrow and enclosed space. The objective of this study was to evaluate the exposure levels to dust, ultra fine dust(PM2.5) and black carbon(BC) among aircraft cabin cleaners. Methods: Active personal air sampling for respirable dust(n=73) and BC(n=47) was conducted during quick transit cleaning(cabin general and vacuum-specific) and seat cover replacement and total dust and PM2.5 were area-air-sampled as well. Also, size distribution of particle was identified with the cleaning workers targeted. Dusts were collected with PVC filters using gravimetric analysis. The concentration of PM2.5 and the particle size distribution were measured with real-time direct reading portable equipment using light scattering analysis. The concentration of BC was measured by aethalometer(filter-based real-time light absorption analysis instrument). Results: The geometric mean of respirable dust was the highest at vacuum cleaning as 74.4 ㎍/m3, following by replacing seat covers as 49.3 ㎍/m3 and cabin general cleaning as 47.8 ㎍/m3 . The arithmetic mean of PM2.5 was 4.83 ~ 9.89 ㎍/m3 inside the cabin, and 28.5~44.5 ㎍/m3 outside the cabin(from bus and outdoor waiting space). From size distribution, PM2.5/PM10 ratio was 0.54 at quick transit cleaning and 0.41 at replacing seat covers. The average concentration of BC was 2~7 ㎍/m3, showing a high correlation with the PM2.5 concentration. Conclusions: The hazards concentration levels of aircraft cabin cleaners were very similar to those of roadside outdoor workers. As the main source of pollution is estimated to be diesel vehicles operating at airports, and it is necessary to replace older vehicles, strengthen pollutant emission control regulations, and introduce electric vehicles. In addition, it is necessary to provide as part of airport-inftastructure a stable standby waiting space for aircraft cabin cleaners and introduce a systematic safety and health management system for all workers in the aviation industry.

Artificial Neural Network with Firefly Algorithm-Based Collaborative Spectrum Sensing in Cognitive Radio Networks

  • Velmurugan., S;P. Ezhumalai;E.A. Mary Anita
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제17권7호
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    • pp.1951-1975
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    • 2023
  • Recent advances in Cognitive Radio Networks (CRN) have elevated them to the status of a critical instrument for overcoming spectrum limits and achieving severe future wireless communication requirements. Collaborative spectrum sensing is presented for efficient channel selection because spectrum sensing is an essential part of CRNs. This study presents an innovative cooperative spectrum sensing (CSS) model that is built on the Firefly Algorithm (FA), as well as machine learning artificial neural networks (ANN). This system makes use of user grouping strategies to improve detection performance dramatically while lowering collaboration costs. Cooperative sensing wasn't used until after cognitive radio users had been correctly identified using energy data samples and an ANN model. Cooperative sensing strategies produce a user base that is either secure, requires less effort, or is faultless. The suggested method's purpose is to choose the best transmission channel. Clustering is utilized by the suggested ANN-FA model to reduce spectrum sensing inaccuracy. The transmission channel that has the highest weight is chosen by employing the method that has been provided for computing channel weight. The proposed ANN-FA model computes channel weight based on three sets of input parameters: PU utilization, CR count, and channel capacity. Using an improved evolutionary algorithm, the key principles of the ANN-FA scheme are optimized to boost the overall efficiency of the CRN channel selection technique. This study proposes the Artificial Neural Network with Firefly Algorithm (ANN-FA) for cognitive radio networks to overcome the obstacles. This proposed work focuses primarily on sensing the optimal secondary user channel and reducing the spectrum handoff delay in wireless networks. Several benchmark functions are utilized We analyze the efficacy of this innovative strategy by evaluating its performance. The performance of ANN-FA is 22.72 percent more robust and effective than that of the other metaheuristic algorithm, according to experimental findings. The proposed ANN-FA model is simulated using the NS2 simulator, The results are evaluated in terms of average interference ratio, spectrum opportunity utilization, three metrics are measured: packet delivery ratio (PDR), end-to-end delay, and end-to-average throughput for a variety of different CRs found in the network.

연속흐름주입-수소화물생성-유도결합플라스마 질량분석장치를 이용한 바닷물표준시료중의 극미량 비소분석방법의 확립 (Determination of trace arsenic in seawater by flow injection-hydride generation inductively coupled plasma mass spectrometry)

  • 서정기
    • 분석과학
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    • 제21권4호
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    • pp.316-325
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    • 2008
  • 연속흐름주입-수소화물생성-유도결합플라스마질량분석장치를 사용하여 바닷물시료중의 비소를 분석하였다. 두 종류의 바닷물표준시료인 CASS-4, NASS-5를 사용하여 측정값과 인증값을 비교함으로써 본 분석법의 정확성을 확인하였다. 분석결과 CASS-4의 경우 $1.17{\pm}0.07{\mu}g/L$ (인증값 $1.11{\pm}0.16{\mu}g/L$), NASS-5의 경우 $1.24{\pm}0.08{\mu}g/L$ (인증값 $1.27{\pm}0.12{\mu}g/L$)의 값을 얻었다. 이는 각각 독립적으로 5회 측정된 결과의 확장불확도로 표시된 결과이며 CASS-4의 경우 6.2%, NASS-5의 경우 6.8%이었으며 모두 인증값의 불확도 범위안에 있었다. 검량선의 기울기와 바탕값의 표준편차로부터 구한 $As^+$ (m/z=74.9216)의 검출한계는 0.01 ug/kg이었다. 검량선의 직선성은 매우 양호하였다. ($R^2=1$). DRC gas로 산소기체를 사용하여 $AsO^+$ (m/z=90.9165)로 검출하는 방법을 사용하여 결과를 비교하였으며 분석감도는 약 25배 정도 감소하였으나, 검량선의 직선성이 매우 잘 나타났으며, 분석결과도 $As^+$(m/z=74.9216)로 검출할 때와 동일한 결과를 얻을 수 있었다.

여름과 가을의 주택실내 초미세먼지(PM2.5) 농도 측정 및 영향요인 비교 (Measurement of PM2.5 Concentrations and Comparison of Affecting Factors in Residential Houses in Summer and Autumn)

  • 김동준;민기홍;신지훈;최영태;최길용;심상효;양원호
    • 한국환경보건학회지
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    • 제50권1호
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    • pp.16-24
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    • 2024
  • Background: Indoor PM2.5 concentrations in residential houses can be affected by various factors depending on the season. This is because not only do the climate characteristics depend on the season, but the activity patterns of occupants are also different. Objectives: The purpose of this study is to compare factors affecting indoor PM2.5 concentrations in apartments and detached houses in Daegu according to seasonal changes. Methods: This study included 20 households in Daegu, South Korea. The study was conducted during the summer (from July 10 to August 10, 2023) and the autumn (from September 11 to October 9, 2023). A sensor-based instrument for PM2.5 levels was installed in the living room of each residence, and measurements were taken continuously for 24 hours at intervals of one minute during the measurement period. Based on the air quality monitoring system data in Daegu, outdoor PM2.5 concentrations were estimated using ordinary kriging (OK) in Python. In addition, the indoor activities of the occupants were investigated using a time-activity pattern diary. The affecting factors of indoor PM2.5 concentration were analyzed using multiple regression analysis. Results: Indoor and outdoor PM2.5 concentrations of the residences during summer were 15.27±11.09 ㎍/m3 and 11.52±7.56 ㎍/m3, respectively. Indoor and outdoor PM2.5 concentrations during autumn were 13.82±9.61 ㎍/m3 and 9.57±5.50 ㎍/m3, respectively. The PM2.5 concentrations were higher in summer compared to autumn both indoors and outdoors. The primary factor affecting indoor PM2.5 concentration in summer was occupant activity. On the other hand, during the autumn season, the primary affecting factor was outdoor PM2.5 concentration. Conclusions: Indoor PM2.5 concentration in residential houses is affected by occupant activity such as the inflow of outdoor PM2.5 concentration, cooking, and cleaning, as found in previous studies. However, it was revealed that there were differences depending on the season.

중학교 "환경" 교과의 교수.학습 및 평가 방법 연구 (A Study on Teaching-Learning and Evaluation Methods of Environmental Studies in the Middle School)

  • 남상준
    • 한국환경교육학회지:환경교육
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    • 제7권1호
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    • pp.1-17
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    • 1994
  • This study was performed to determine appropriate teaching-learning and evaluation methods for Environmental Studies. To promote the relevance of our study to the needs of the schools and concerned educational communities of environmental education, we reviewed related literature, conducted questionnaire surveys, interviewed related teachers and administrator, held meetings with experts, and field-tested our findings. For selecting and developing teaching-learning methods of Environmental Studies, findings of educational research in general are considered. moreover, principles of environmental education, general aim of environmental education, orientations of environmental education, and developmental stages of middle school students in educational psychology were attended. In addition, relevance to the purpose of the Environmental Studies curriculum, appropriateness for value inquiry as well as knowledge inquiry, small group centered class organization, social interaction centered teaching-learning process, regional environmental situation, significance of personal environment, evaluation methods of Environmental Studies, multi- and inter-disciplinary contents of the Environmental Studies textbook, suitability to the evaluation methods of Environmental Studies, and emphasis on the social interaction in teaching-learning process were regarded. It was learned the Environmental Studies can be taught most effectively in via of holding discussion sessions, conducting actual investigation, doing experiment-practice, doing games and plate, role-playing and carrying out simulation activities, and doing inquiry. These teaching-learning methods were field-tested and proved appropriate methods for the subject. For selecting and developing evaluation method of Environmental Studies, such principles and characteristics of Environmental Studies as objective domains stated in the Environmental Studies curriculum, diversity of teaching-learning organization, were appreciated. We categorized nine evaluation methods: the teacher may conduct questionnaire surveys, testings, interviews, non-participatory observations; they may evaluate student's experiment-practice performances, reports preparation ability, ability to establish a research project, the teacher may ask the students to conduct a self-evaluation, or reciprocal evaluation. To maximize the effect of these methods, we further developed an application system. It considered three variables, that is, evaluates, evaluation objectives domains, and evaluation agent, and showed how to choose the most appropriate methods and, when necessary, how to combine uses of different methods depending on these variables. A sample evaluation instrument made on the basis of this application system was developed and tested in the classes. The system proved effective. Pilot applications of the teaching-learning methods and evaluation method were made simultaneously; and the results and their implications are as follows. Discussion program was applied in a lesson dealing with the problems of waste disposal, in which students showed active participation and creative thinking. The evaluation method used in this lesson was a multiple-choice written test for knowledge and skills. It was shown that this evaluation method and device are effective in helping students' revision of the lesson and in stimulating their creative interpretations and responces. Pupils showed great interests in the actual investigation program, and this programme was proved to be effective in enhancing students' participation. However, it was also turned out that there must be pre-arranged plans for the objects, contents and procedures of survey if this program is to effective. In this lesson, non-participatory observation methods were used with a focus on the attitudes of students. A scaled reported in general description rather than in grade. Experiment-practice programme was adopted in a lesson for purifying contaminated water and in this lesson, instruction objectives were properly established, the teaching-learning process was clearly specified and students were highly motivated. On the other hand, however, it was difficult to control the class when some groups of students require more times to complete their experiment, and sometimes different results. As regards to evaluation, performance observation test were used for assessing skills and attitudes. If teachers use well-prepared Likert scale, evaluation of all groups within a reasonablely short period of time will be possible. The most effective and successful programme in therms of students' participation and enjoyment, was the 'ah-nah-bah-dah-market' program, which is kind of game of the flea market. For better organized program of this kind, however, are essential, In this program, students appraise their own attitudes and behavior by responding to a written questionnaire. In addition, students were asked to record any anecdotes relating to self-appraisal of changes on one's own attitudes and behaviours. Even after the lesson, students keep recording those changes on letters to herself. Role-playing and simulation game programme was applied to a case of 'NIMBY', in which students should decide where to located a refuse dumping ground. For this kind of programme to e successful, concepts and words used in the script should be appropriate for students' intellectual levels, and students should by adequately introduced into the objective and the procedures of the lessons. Written questionnaire was used to assess individual students' attitudes after the lesson, but in order to acquire information on the changes of students' attitudes and skills, pre-test may have to be made. Doing inquiry programme, in which advantages in which students actually investigated the environmental influence of the areas where school os located, had advantages in developing students' ability to study the environmental problems and to present the results of their studies. For this programme to be more efficient, areas of investigation should be clearly divided and alloted to each group so that repetition or overlap in areas of study and presentation be avoided, and complementary wok between groups bee enhanced. In this programme, teacher assessed students' knowledge and attitudes on the basis of reports prepared by each group. However, there were found some difficults in assessing students' attitudes and behaviours solely on the grounds of written report. Perhaps, using a scaled checklist assessing students' attitudes while their presentation could help to relieve the difficulties.

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LCC 기법을 통한 가축분뇨처리시설의 경제성 분석 (Economic Analysis of the Livestock Manure Treatment System Using Life-Cycle Cost Technique)

  • 김재환;조승희;곽정훈;최동윤;정광화;정의수;정만순;박성균
    • 한국축산시설환경학회지
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    • 제17권sup호
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    • pp.61-68
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    • 2011
  • 본 연구는 가축분뇨 처리시설의 평가 및 최적 선택의 의사결정에 있어서, 시설물은 내구성이 있는 자산이므로 내용연수 전 기간에 걸친 비용측면에서의 경제성이 고려되어야 하는 바, 이를 위하여 LCC (Life Cycle Cost) 기법의 적용 가능성을 검토하고자 수행하였다. 경제성의 비교 분석을 위해 양돈 분뇨 1일 100톤 처리규모의 공동자원화시설 설치 공법들 중 4개 공법에 대한 시설투자 및 연간 운영비를 조사하였는데, 초기 투자비는 2,699~3,202 백만원 수준으로 T 공법이 가장 높았고 E 공법이 가장 낮았다. 연간 운영비에 있어서는 378~498 백만원 수준으로 T 공법, J 공법, E 공법, B 공법 순으로 유리한 것으로 조사되었다. LCC 분석을 위해 한국은행 및 통계청의 10년간 ('00~'09) 자료를 이용하여 이자율 (4.7%), 물가상승율 (3.13%), 실질 할인율 (1.52%)를 기준하고, 현가계수 산정을 위해 내용연수를 토목 건축 (30년), 기계 (10년), 전기계장 (15년) 으로 기준하였다. 이를 바탕으로 한 분석 결과, 톤당 운영비로 보면 17,570~18,998원/톤 수준으로서 E공법이 17,570원/톤으로 가장 낮은 반면, B 공법이 20,661원/톤으로 가장 높아 상대적으로 가장 비경제적이었다. 특히 초기투자비가 높더라도 연간 운영비가 낮은 T 공법이 초기투자비는 T 공법보다 낮으나 연간 운영비가 상대적으로 높은 B 공법에 비해 LCC가 낮게 평가되었다. 따라서 가축분뇨 처리시설의 경제적 측면에서의 공법 선택에 있어서는 초기시설투자비 또는 연간 운영비 중 어느 한쪽만 평가하여 결정하기 보다는 LCC 분석을 적용하여 평가하는 것이 합리적임을 알 수 있다. 또한 경제성 분석에 있어서, 불확실성에 따른 LCC 분석 결과의 변화를 파악하기 위해 '00~'09년 간의 할인율 변동폭을 적용하여 민감도분석을 실시한 결과, 변동범위 안에서 변화하더라도 각 대안별 비용우위에 대한 변화는 달라지지 않아 안정적이라고 할 수 있다. 따라서 LCC를 이용한 경제성 평가는 가축분뇨 처리시설의 선택을 위한 의사결정에 유용한 평가 지표가 될 수 있으리라 판단된다. 향후 분석의 신뢰성 제고와 활성화를 위해서는 각 비용요소들에 대해 공신력 있는 데이터베이스 구축이 대단히 중요하며, 아울러 시설평가 시 정성적인 요인도 고려할 수 있는 연구가 추가적으로 이루어져야 할 것이다.

정보시스템 사용과 성과에 있어서 자발성의 조절효과에 관한 연구 (A Study on the Moderating Effect of Perceived Voluntariness in the Organizational Information System Usage and Performance)

  • 이승창;이호근;정창욱;정남호;서응교
    • Asia pacific journal of information systems
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    • 제19권2호
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    • pp.195-221
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    • 2009
  • According to an industry report, a large number of organizations have invested in Organizational Information System(OIS) in the past few years. Several research results indicate that successful investments in OIS lead to productivity enhancement, while failed ones result in undesirable consequences such as financial losses and dissatisfaction among employees. In spite of huge investments, however, many organizations have failed in achieving the hoped-for returns from OIS. Thus, understanding user acceptance, adoption, and usage of new IS(Information Systems) is an important issue for IS practitioners. Indeed, study of the user acceptance of new information system has been one of the most important research topics in the contemporary IS literature. Several theoretical models are tested to examine 'user acceptance' and 'usage behavior' in IS context. While many research models incorporate 'ease of use' or 'usefulness' as important factors in explaining user acceptance, Technology Acceptance Model(TAM) has been one of the most widely applied models in user acceptance and usage behavior. Even in recent IS studies that employ theories of innovation diffusion in the area of IS implementation, a major focus has been on the user's perception of information technologies. In this research, we study 'voluntariness' as an important factor in IS acceptance by users. Voluntariness is defined as "the degree to which the use of the innovation is perceived as being voluntary, or of free will" When examining the diffusion of accepting OIS, a thoughtful consideration should be given to 'perceived voluntariness.' Current article has following research questions: 1) What models are appropriate to explain the success of OIS? and 2) How does the 'voluntariness' affect the success of OIS? In order to answer these questions, a research model is proposed to describe the detailed nature of association among three independent variables (IT usage level, task interdependency, and organizational support), a mediating variable (IS usage), a dependent variable (perceived performance), and a moderating variable(perceived voluntariness). The central claim of this article is that organizations hardly realize expected returns from OIS investments unless perceived voluntariness is effectively managed after operating OIS. As an example of OIS in this study we have selected the Intranet of Republic of Korea Air Force (ROKAF). ROKAF has implemented the Intranet in an attempt to improve communication and coordination within the organization. To test our research model and hypotheses, survey questionnaires were first sent out to 400 Intranet users. With the assistance of ROKAF, Intranet users were initially identified among its members, and subjects were randomly drawn from the pool. 377 survey responses were finally returned. The unit of measurement and analysis in this research is a personal level. Path analysis based on structural equation modeling was used to test research hypotheses. Construct validity represents accordance between the theoretical base concept of constructs and its measurement items. Tests for the reliability and discriminant validity are accepted, thus verifying our survey instrument. In this research, we have proposed a conceptual framework to highlight the importance of perceived voluntariness after organization deploys OIS. The results of our analysis present several key finding. First, all three independent variables (IT usage level, task interdependency, and organizational support) have significant effects on IS usage, which will eventually improve performance. Thus, IS usage plays a mediating role between antecedent variables (IT usage level. task interdependency, and organizational support) and performance improvement. Second, the effect of the task dependency was the highest for IS usage among the three antecedent variables. This is highly plausible since one of the Intranet's major capabilities is to facilitate communication among members within an organization. Accordingly, we conclude that the higher the task dependency, the higher Intranet usage. The effect of user's IT usage level was the second, while the effect of the organizational support was the third. Finally, the perceived voluntariness plays a pivotal role in enhancing perceived performance in personal level after launching the Intranet. Relationships among investigated variables were significantly different between groups with a high level and a low level of voluntariness. The impact of the Intranet usage on the performance was greater in the higher level voluntariness group than in the lower one. For the lower level voluntariness group, the user's IT usage had the highest effect on the Intranet usage among the three antecedent variables. In short, our study suggests that the higher the perceived voluntariness is the more IS usage will be. Perceived voluntariness was found to have a moderating effect on the relationships among user IT usage level, task interdependency, IS usage, and perceived performance, supporting all the hypotheses on the moderating effect. Most of all, user IT usage level has the strongest influence on IS usage, indicating that users with superior IT usage are more likely to enjoy a high level of perceived performance.