• Title/Summary/Keyword: Requirement Engineering process

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A Single-Bit 3rd-Order Feedforward Delta Sigma Modulator Using Class-C Inverters for Low Power Audio Applications (저전력 오디오 응용을 위한 Class-C 인버터 사용 단일 비트 3차 피드포워드 델타 시그마 모듈레이터)

  • Hwang, Jun-Sub;Cheon, Jimin
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.15 no.5
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    • pp.335-342
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    • 2022
  • In this paper, a single-bit 3rd-order feedforward delta sigma modulator is proposed for audio applications. The proposed modulator is based on a class-C inverter for low voltage and power applications. For the high-precision requirement, the class-C inverter with regulated cascode structure increases its DC gain and acts as a low-voltage subthreshold amplifier. The proposed Class-C inverter-based modulator is designed and simulated in 180-nm CMOS process. With no performance loss and a low supply voltage compatibility, the proposed class-C inverter-based switched-capacitor modulator achieves high power efficiency. This design achieves an signal-to-noise-and-distortion ratio (SNDR) of 93.9 dB, an signal-to-noise ratio (SNR) of 108 dB, an spurious-free dynamic range (SFDR) of 102 dB, and a dynamic range (DR) of 102 dB at a signal bandwidth of 20 kHz and a sampling frequency of 4 MHz, while only using 280 μW of power consumption from a 0.8-V power supply.

Investigation of the Bonding Stress of the 2nd Barrier for LNG Carrier Cargo Containment System Considering Various Working Conditions (다양한 작업 조건을 고려한 LNG 운반선 화물창 2차 방벽의 극저온 접착강도 분석)

  • Jeong-Hyeon Kim;Hee-Tae Kim;Byeong-Kwan Hwang;Seul-Kee Kim;Tae-Wook Kim;Doo-Hwan Park;Jae-Myung Lee
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.3
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    • pp.499-507
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    • 2023
  • The core of the liquefied natural gas (LNG) carrier cargo containment system (CCS) is to store and transport LNG safely under temperatures below -163 degrees Celsius. The secondary barrier of the LNG CCS is adopted to prevent LNG leakage from CCS to the ship's hull structure. Recently, as the size of the LNG CCS increases, various studies have been conducted on the applied temperature and load ranges. The present study investigates the working condition-dependent bonding strength of the PU15 adhesives of the secondary barrier. In addition, the mechanical performance is analyzed at a cryogenic temperature of -170 degrees Celsius, and the failure surface and failure mode are investigated depending on the working condition of the bonded process. Even though the RSB and FSB-based fracture mode was confirmed, the results showed that all the tested scenarios satisfied the minimum requirement of the regulation.

Heat Treatment Deformation Analysis of Bearing Considering Phase Transformation (상변태를 고려한 베어링의 열처리 변형 해석)

  • S.P. Lee;S.J. Lee;T.B. Kim;K.T. Cho
    • Journal of the Korean Society for Heat Treatment
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    • v.36 no.6
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    • pp.351-358
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    • 2023
  • Bearings are mechanical components that support loads and transmit rotation. The inner and outer rings come into contact with the rotating mechanism, requiring a very high level of hardness. To meet this requirement, heat treatment is commonly performed. The heat treatment process inherently involves thermal deformation. Particularly in the case of large bearings, significant deformation relative to the bearing's shape can occur, making accurate deformation prediction during heat treatment essential. However, predicting deformation in heat treatment is challenging due to the simultaneous consideration of phase transformation, heat transfer, and bearing deformation. In this study, an analysis of heat treatment-induced deformation in bearings was conducted, taking phase transformation into account. The thermal and mechanical properties were calculated based on the chemical composition of the bearing material. This information was then used to perform a deformation-heat transfer-phase transformation analysis. To validate the reliability of the analysis, experiments were conducted under the same conditions. When comparing the analysis and experimental results, differences in deformation were observed. These differences were attributed to variations in phase transformation conditions between the analysis and experiments. Consequently, it is anticipated that supplementing these results will enable the prediction of deformation while considering phase transformation conditions in bearings.

Development of the Information Delivery System for the Home Nursing Service (가정간호사업 운용을 위한 정보전달체계 개발 I (가정간호 데이터베이스 구축과 뇌졸중 환자의 가정간호 전산개발))

  • Park, J.H;Kim, M.J;Hong, K.J;Han, K.J;Park, S.A;Yung, S.N;Lee, I.S;Joh, H.;Bang, K.S
    • Journal of Korean Academic Society of Home Health Care Nursing
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    • v.4
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    • pp.5-22
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    • 1997
  • The purpose of the study was to development an information delivery system for the home nursing service, to demonstrate and to evaluate the efficiency of it. The period of research conduct was from September 1996 to August 31, 1997. At the 1st stage to achieve the purpose, Firstly Assessment tool for the patients with cerebral vascular disease who have the first priority of HNS among the patients with various health problems at home was developed through literature review. Secondly, after identification of patient nursing problem by the home care nurse with the assessment tool, the patient's classification system developed by Park (1988) that was 128 nursing activities under 6 categories was used to identify the home care nurse's activities of the patient with CAV at home. The research team had several workshops with 5 clinical nurse experts to refine it. At last 110 nursing activities under 11 categories for the patients with CVA were derived. At the second stage, algorithms were developed to connect 110 nursing activities with the patient nursing problems identified by assessment tool. The computerizing process of the algorithms is as follows: These algorithms are realized with the computer program by use of the software engineering technique. The development is made by the prototyping method, which is the requirement analysis of the software specifications. The basic features of the usability, compatibility, adaptability and maintainability are taken into consideration. Particular emphasis is given to the efficient construction of the database. To enhance the database efficiency and to establish the structural cohesion, the data field is categorized with the weight of relevance to the particular disease. This approach permits the easy adaptability when numerous diseases are applied in the future. In paralleled with this, the expandability and maintainability is stressed through out the program development, which leads to the modular concept. However since the disease to be applied is increased in number as the project progress and since they are interrelated and coupled each other, the expand ability as well as maintainability should be considered with a big priority. Furthermore, since the system is to be synthesized with other medical systems in the future, these properties are very important. The prototype developed in this project is to be evaluated through the stage of system testing. There are various evaluation metrics such as cohesion, coupling and adaptability so on. But unfortunately, direct measurement of these metrics are very difficult, and accordingly, analytical and quantitative evaluations are almost impossible. Therefore, instead of the analytical evaluation, the experimental evaluation is to be applied through the test run by various users. This system testing will provide the viewpoint analysis of the user's level, and the detail and additional requirement specifications arising from user's real situation will be feedback into the system modeling. Also. the degree of freedom of the input and output will be improved, and the hardware limitation will be investigated. Upon the refining, the prototype system will be used as a design template. and will be used to develop the more extensive system. In detail. the relevant modules will be developed for the various diseases, and the module will be integrated by the macroscopic design process focusing on the inter modularity, generality of the database. and compatibility with other systems. The Home care Evaluation System is comprised of three main modules of : (1) General information on a patient, (2) General health status of a patient, and (3) Cerebrovascular disease patient. The general health status module has five sub modules of physical measurement, vitality, nursing, pharmaceutical description and emotional/cognition ability. The CVA patient module is divided into ten sub modules such as subjective sense, consciousness, memory and language pattern so on. The typical sub modules are described in appendix 3.

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A Study on the Physical Properties of Recycled Aggregates Using Concrete of Changing Waste Pottery Blain Fineness (폐도자기 분말도 변화에 따른 순환골재 사용 콘크리트의 물리적 특성에 관한 연구)

  • Ryu, Hyun-Gi;Park, Jeong-Min;Joung, Jae-Ho;Kim, Eui-Chang;Yoon, Seung-Joe
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.2
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    • pp.119-127
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    • 2011
  • Objective of this study is to identify properties on strength increase of hardened concrete and fluidization of non-hardened concrete using waste ceramics generated by construction waste, which is a type of industrial waste, and by ceramics, which is a clay plastic, during its production process, and determine length change ratio caused by drying shrinkage during substitution of recycle aggregate and waste ceramics, and whether they can be used as concrete compounds. Slump of non-hardened concrete exhibited the best fluidization and formability at recycled aggregate's replacement ratio of 60% driven by higher substitution ratio of recycled aggregate and waste ceramics while air content met the KS requirement when substitution ratio of waste ceramics was $4,000cm^2/g$. Compressive strength of hardened concrete exceeded the requirements at early age and standard age and temperature dropped by roughly $6{\sim}10^{\circ}C$ less than the standard at maximum temperature in adiabatic temperature increase, which will hopefully result in stronger durability.

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Improvement of estimating method for construction management service fee by case study (사례분석을 통한 건설사업관리 대가산정 방법 개선)

  • Lee, Ung-Kyun;Yoo, Wi-Sung;Kim, Dong-In;Kim, Tae-Hoon;Cha, Min-Soo;Cho, Hun-Hee
    • Korean Journal of Construction Engineering and Management
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    • v.13 no.4
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    • pp.16-24
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    • 2012
  • The objective of this paper is to suggest the improvement of estimating system for construction management (CM) service fee through the analysis of the previous literatures and criteria and case study. In order to do this, this paper considered the relevance of existing criteria to estimate the CM service fee, the condition of input ratio of engineering resources in the real cases, and current utilization strategy of nonresident technical engineers. Based on the analysis, the following problems were identified; a) the different estimating system for CM fee and construction supervision fee, b) impractical estimating system for the CM fee, and c) inappropriate allocation of human resources for CM. Consequently, this paper suggested the following 4 items for the improvement of the existing system; (1) modification of the current structure of CM fee calculation, (2) rationalization of current level of the CM fee which is required to be raised approximately 5.4 percent compared to design or supervision fee, (3) securement of elasticity of the input ratio of engineering resources from the inception phase, and (4) development of the utilization strategy of nonresident engineers based on the technical requirement of the jobsite. Thus, it is anticipated that this research would affect the compensation package of CM in order to make the estimation process of CM service fee more efficient and to revitalize CM as business.

Reverse Osmosis Treatment of Swine Wastewater with Various Pretreatment Systems (축산 폐수의 전처리 방법과 역삼투압 처리)

  • Park, Soon Ju;Kim, Moon Il;Kim, Do Yun;Chang, Ho Nam;Chang, Seung Teak
    • Clean Technology
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    • v.9 no.2
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    • pp.49-55
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    • 2003
  • The generation of livestock wastewater in Korea amounts to $130,000m^3/day$, 0.43% of the total waste water volume, but which corresponds to 8.6% of total BOD loading. Furthermore this wastewater contains a large amount of nitrogen and phosphorus that are major causes of eutrophication in rivers and lakes. The average volume of livestock wastewater in a Korea's single farm is only $2.5m^3/day$, which necessitates development of a simple and economical process for the removal of nitrogen and phosphorus. Introduction of filtration method removes more than 90% of suspended solids. Subsequent application of reverse osmosis removes more then 95% of total nitrogen and phosphorus in the wastewater. The effluent of this treatment will yield less than 200 mg/L of total nitrogen and 1 mg/L of total phosphorous, which are lower than 260 mg/L of total N and 50 mg/L of total P, the regulation values of Ministry of Environment, Korea. Treating $2m^3/day$ of livestock wastewater was found to be feasible with the application of filtration and reverse osmosis and the electricity requirement was estimated to be about 30 Kwh/month.

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Derivation of Anti-Tamper System Requirements Based on CMVP Standard for Technology Protection of Weapon Systems (무기 시스템의 기술 보호를 위한 CMVP 표준 기반의 Anti-Tamper 시스템 요구사항 도출)

  • Lee, Min-Woo;Lee, Jae-Chon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.4
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    • pp.470-478
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    • 2019
  • As the growth of the domestic defense industry is remarkable regarding technology level and export size, technology protection is necessary. Particularly, there is a need to apply anti-tamper measures to prevent critical technologies from illegally being taken out of weapon systems. However, there is no security protection strategy and system built yet in ROK. Precedent studies discussed the trend analysis and technical research for specific protective techniques, and the application of anti-tamper using limited procedures was provided. Recently, methods of how to select the technology for protection were studied based on risk management. Nonetheless, these studies cannot be associated with the acquisition process for the whole life-cycle, having difficulty with actual development and evaluation of the weapon systems. The objective of our study is to derive the system requirements of the weapon system for which anti-tamper measures have been determined to apply. Specifically, requirements items suitable for the development of anti-tamper weapon systems were derived based on ISO/IEC 19790, the CMVP standard for the development and verification of cryptographic modules. Also, its utilization in technical reviews and test & evaluations was presented. The usefulness of the research results was confirmed through inductive inference and comparative evaluation. The result can be expected to play a role in initiating extensive activities needed for technology protection of the weapon systems.

Treatment Characteristics of Soil Clothing Contact Oxidation Process using Bio-media (생물담체를 충진한 토양피복 산화접촉공정의 하수처리특성)

  • Kim, Hong-Jae;Kang, Jae-Hee;Lee, Ki-Seok;Motoki, Kubo;Kang, Chang-Min;Chung, Seon-Yong
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.4
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    • pp.414-419
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    • 2005
  • This study was performed to compare the treatment efficiencies of two media, newly developed Bio-rock and conventional gravel, in soil clothing contact oxidation process. The composition of synthetic wastewater were $COD_{Cr}$ $150{\sim}370\;mg/L$, $BOD_5$ $150{\sim}270\;mg/L$, T-N $20{\sim}60\;mg/L$, T-P $5{\sim}25\;mg/L$, pH 7 and 2 mL/L of trace element solution. The experiment using two reactors was comparatively conducted for the flow rate of 40 L/d for 13 months, respectively. Initially Bio-rock reactor was increased to pH 12 due to $Ca(OH)_2$ with hydration of cement, but gravel reactor was dropped to pH 4 due to the degradation of organic material and nitrification. This significant pH variation deteriorated the growth and activity of microorganism. But the high pH of Bio-rock seems favorite to ammonia stripping and precipitation of phosphate. Such pH variation of Bio-rock and gravel reactors were finally stabilized to pH 8 and pH 6, respectively. The removal efficiencies of organic compounds from Bio-rock reactor were 96% of $COD_{Cr}$, 98% of $BOD_5$, 80% of T-N and 85% of T-P which stably coping against variation of influent concentration. But those of gravel reactor were 96% of $COD_{Cr}$, 96% of $BOD_5$, 42% of T-N and 40% of T-P, respectively. The Bio-rock was 2 times higher than T-N and T-P in treatment efficiency. And electron-microscopic examination showed that Bio-rock was more favorable to microbial adherence than gravel. The microbial populations were $5.2{\times}10^6\;CFU/mL$ of Bio-rock reactor compared to $2.6{\times}10^6\;CFU/mL$ in gravel reactor. In result Bio-rock was favor to microbial adherence and high treatment efficiency in spite of variation of influent concentration which had the advantages in saving running time and reducing site requirement.

Design and Implementation of SQL Audit Tool for Database Performance (데이터베이스 성능을 위한 SQL 감리 도구의 설계 및 구현)

  • Liu, Chen;Kim, Taewoo;Zheng, Baowei;Yeo, Jeongmo
    • KIPS Transactions on Software and Data Engineering
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    • v.5 no.5
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    • pp.203-208
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    • 2016
  • Information system audit is the requirement to configure the information system successfully. However, there is a problem with reduction of efficiency in the audit work when the system capacity is growing up. In the subsidiary field of information system audit, there is the same problem. In this paper, we will focus on the database audit, and implement an SQL audit tool in order to improve the performance of a database. During the designing phase of the SQL audit tool which aim to improve the performance of a database, we have analyzed the requirements of SQL audit work. Based on the aforementioned them, the process of the SQL audit tool has been designed with SQL audit features in accordance with information audit process. During the implementation phase, we have implemented 3 main function modules according to the output of the design phase. The main modules we implemented are the audit job definition module, audit job executing module and result reporting module. With the implemented tool, it applied to an Electric Power Corporation project in China and compared with other tools that are able to use SQL audit. In this paper, the implemented SQL audit tool is able to perform the general SQL audit work and to reduce the cost of the audit work for database performance and to raise the accuracy of result and to apply the extended inspection rule which need to use SQL parsing.