• Membrane and Water Treatment
• /
• 제14권2호
• /
• pp.55-63
• /
• 2023

In this study, the influence of different IEMs (ion exchange membranes) to performance of the hypochlorite electrolysis unit with Cl₂ recovery stream was investigated. More specifically, Nafion 117-a representative cation exchange membrane (CEM)-and aminated polypheylene oxide (APPO)-an anion exchange membrane (AEM)-were installed in the hypochlorite electrolysis unit, and the performance and the energy efficiency of the units were evaluated and compared. Regardless of whether CEM (Nafion 117) or AEM (APPO) was installed, the rate of hypochlorite generation was increased (by up to 24.3% and 22.2% for Nafion 117 and APPO, respectively) compared with the unit without an IEM. On the other hand, the power efficiency and the optimum operation condition of hypochlorite production units seem to depend on the conductivity and stability of the installed IEM. As the result, between Nafion 117 and APPO, higher performance and efficiency were achieved with Nafion 117, due to excellent conductivity and stability of the membrane.

• Advances in aircraft and spacecraft science
• /
• 제10권4호
• /
• pp.369-391
• /
• 2023

In our research we have offered a solid solution for aeronautical analysis. which can guarantee the asymptotic stability of coupled nonlinear facilities. According to the theoretical solutions and methods presented, the engine of this aircraft is a small high-bypass turbofan engine. using the non-linear aero-motor control approach and this paper focuses on the power management function of the aero-motor control system. These include static controls and transient controls. A mathematical model of the high-bypass-ratio two-spool unmixed-flow aeroengine was developed through a set of nonlinear dynamic equations verified by experimental data. A single actuator using the displacement method is designed to maintain a certain level of thrust under steady-state conditions. and maintains repeatable performance during transient operation from the requested thrust phase to the next. A single controller can compensate for the effects of noise and harmonic noise at many performance points. And the dynamic performance of a single controller is satisfactory during the transient. for fairness Numerical and computer experiments are described in the perfection of the methods we offer in research.

• Smart Structures and Systems
• /
• 제33권2호
• /
• pp.133-143
• /
• 2024

Piezoelectric (PZT) actuators have been widely used in precision positioning fields for their excellent displacement resolution. However, due to the inherent characteristics of piezoelectric actuators, hysteresis has been proven to greatly reduce positioning performance. In this paper, five mathematical hysteretic models based on activation function are proposed to characterize the nonlinear hysteresis characteristics of piezoelectric actuators. Then the performance of the proposed models is verified by particle swarm optimization (PSO) algorithm and the experiment data. Thirdly, the fitting performance of the proposed models is compared with the classical Bouc-Wen model. Finally, the performance of the five proposed models in modelling hysteresis nonlinearity of piezoelectric drivers is compared, in terms of RMSE, MAPE, SAPE and operation efficiency, and relevant suggestions are given.

• Design & Manufacturing
• /
• 제10권1호
• /
• pp.51-54
• /
• 2016

Metal sheet forming has been commonly used as the core technology in manufacturing parts of automobiles. It guarantees the highest production rate due to the process of mass production employing the press die. For precision of the product, the accuracy of the molds and its mechanic structures are considered as essential factors. One of these is fine blanking, which is utilized for the production of the metal sheet spring, with which clear sheer surfaces can be achieved in one operation from the materials. However, the current designs of press dies perform the forming analysis with the molds of rigid body, so they are focused on weight lightening by a rule of thumb. Therefore, this paper practice structural analysis about developing the semi fine-fine blanking technology. The semi fine-blanking can be run through the combination of the hydraulic cylinders and normal presses, so this paper analyze the amount of deformation according to the oil pressure. In addition, based on the plasticity of 50CrV4, the materials of the mold parts, the structural analysis and life analysis are proceeded, so they are expected to be useful as data for manufacturing the mold.

• Hip & pelvis
• /
• 제35권2호
• /
• pp.88-98
• /
• 2023

Purpose: The objectives of this study were to examine the prevalence and risk factors for development of periprosthetic occult femoral fractures during primary cementless total hip arthroplasty (THA) and to assess the clinical consequences of these fractures. Materials and Methods: A total of 199 hips were examined. Periprosthetic occult femoral fractures were defined as fractures not detected intraoperatively and on postoperative radiographs, but only observed on postoperative computed tomography (CT). Clinical, surgical, and radiographic analysis of variables was performed for identification of risk factors for periprosthetic occult femoral fractures. A comparison of stem subsidence, stem alignment, and thigh pain between the occult fracture group and the non-fracture group was also performed. Results: Periprosthetic occult femoral fractures were detected during the operation in 21 (10.6%) of 199 hips. Of eight hips with periprosthetic occult femoral fractures that were detected around the lesser trochanter, concurrent periprosthetic occult femoral fractures located at different levels were detected in six hips (75.0%). Only the female sex showed significant association with an increased risk of periprosthetic occult femoral fractures (odds ratio for males, 0.38; 95% confidence interval, 0.15-1.01; P=0.04). A significant difference in the incidence of thigh pain was observed between the occult fracture group and the non-fracture group (P<0.05). Conclusion: Occurrence of periprosthetic occult femoral fractures is relatively common during primary THA using tapered wedge stems. We recommend CT referral for female patients who report unexplained early postoperative thigh pain or developed periprosthetic intraoperative femoral fractures around the lesser trochanter during primary THA using tapered wedge stems.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2002년도 제3회 최신 분말제품 응용기술 Workshop
• /
• pp.25-37
• /
• 2002

The most important industrial application of gamma radiation in characterizing green compacts is the determination of the density. Examples are given where this method is applied in manufacturing technical components in powder metallurgy. The requirements imposed by modern quality management systems and operation by the workforce in industrial production are described. The accuracy of measurement achieved with this method is demonstrated and a comparison is given with other test methods to measure the density. The advantages and limitations of gamma ray densitometry are outlined. The gamma ray densitometer measures the attenuation of gamma radiation penetrating the test parts (Fig. 1). As the capability of compacts to absorb this type of radiation depends on their density, the attenuation of gamma radiation can serve as a measure of the density. The volume of the part being tested is defined by the size of the aperture screeniing out the radiation. It is a channel with the cross section of the aperture whose length is the height of the test part. The intensity of the radiation identified by the detector is the quantity used to determine the material density. Gamma ray densitometry can equally be performed on green compacts as well as on sintered components. Neither special preparation of test parts nor skilled personnel is required to perform the measurement; neither liquids nor other harmful substances are involved. When parts are exhibiting local density variations, which is normally the case in powder compaction, sectional densities can be determined in different parts of the sample without cutting it into pieces. The test is non-destructive, i.e. the parts can still be used after the measurement and do not have to be scrapped. The measurement is controlled by a special PC based software. All results are available for further processing by in-house quality documentation and supervision of measurements. Tool setting for multi-level components can be much improved by using this test method. When a densitometer is installed on the press shop floor, it can be operated by the tool setter himself. Then he can return to the press and immediately implement the corrections. Transfer of sample parts to the lab for density testing can be eliminated and results for the correction of tool settings are more readily available. This helps to reduce the time required for tool setting and clearly improves the productivity of powder presses. The range of materials where this method can be successfully applied covers almost the entire periodic system of the elements. It reaches from the light elements such as graphite via light metals (AI, Mg, Li, Ti) and their alloys, ceramics ($AI_20_3$, SiC, Si_3N_4, $Zr0_2$, ...), magnetic materials (hard and soft ferrites, AlNiCo, Nd-Fe-B, ...), metals including iron and alloy steels, Cu, Ni and Co based alloys to refractory and heavy metals (W, Mo, ...) as well as hardmetals. The gamma radiation required for the measurement is generated by radioactive sources which are produced by nuclear technology. These nuclear materials are safely encapsulated in stainless steel capsules so that no radioactive material can escape from the protective shielding container. The gamma ray densitometer is subject to the strict regulations for the use of radioactive materials. The radiation shield is so effective that there is no elevation of the natural radiation level outside the instrument. Personal dosimetry by the operating personnel is not required. Even in case of malfunction, loss of power and incorrect operation, the escape of gamma radiation from the instrument is positively prevented.

• 한국조경학회지
• /
• 제48권2호
• /
• pp.10-19
• /
• 2020

공원 프로그램으로 시대 변화에 따른 여가욕구의 다양화에 빠르게 대응할 수 있으며, 이용자와 공원과의 관계를 보다 밀접하게 만들 수 있다. 이러한 이유로 서울시는 1997년의 남산 야외식물원 식물교실프로그램 이후 다양한 프로그램을 개발하여 운영하고 있고, 세 개의 공원녹지사업소에 공원여가과를 신설하여 조직적으로 접근하고 있다. 그러나 관련 연구는 공원 이용자에 집중되어 있다. 이에 본 연구는 프로그램 운영 주체를 대상으로 프로그램을 작동시키는 구조를 드러내고자 한다. 구체적 목적은 '1. 관련 법 및 운영 조직과 인력의 구성을 파악하여 서울시 공원 프로그램을 작동시키는 제도적 특성을 진단, 2. 프로그램 운영비의 조달과 집행, 민관 협력 등 운영방식을 분석, 3. 2015년부터 2017년까지 운영된 구체적 프로그램을 분석하여 프로그램 운영의 구조와 프로그램 간의 관계성 파악'이다. 연구 내용을 종합해 볼 때 첫번째 프로그램 운영의 구조에 있어서는 지원법은 체계적이지 못하나 운영 조직은 체계를 갖추어 나가고 있었다. 두번째 운영방식에서 대부분의 예산은 지방정부가 충당하고 있었고, 민간참여의 단계는 낮았다. 세 번째로 프로그램의 특성을 살펴보았을 때 프로그램은 양적으로는 증가되었지만 특정 주제에 집중되어 있었고, 공원시설을 적극 활용하는 프로그램은 적었다. 이러한 연구 결과를 근거로 세 가지 과제를 제안할 수 있다. 첫째는, '공원 및 녹지 등에 관한 법률'에 공원 프로그램에 대한 개념 및 지원에 관한 내용이 포함되도록 해야 한다는 것이다. 두 번째는, 프로그램의 양적 증가에서 질적 향상으로의 변화가 필요하다는 것이며, 마지막은 공원여가문화 활성화를 위해 서울시 푸른도시국을 시민주도 및 여가문화 지향의 조직으로 개편할 필요가 있다는 것이다. 본 연구는 기존의 많은 공원 프로그램 관련 연구와는 달리 프로그램 이용자가 아닌 서비스 제공자인 공원관리청을 연구 대상으로 했다는데 의의를 갖는다. 연구 결과는 서울시뿐만 아니라, 타 지방정부가 수요자가 중심이 되는 공원 관리 및 운영의 방향성을 제시하는데 기여할 수 있을 것이며, 결과적으로는 시민의 가장 가까운 여가공간으로서 공원의 장기적 비전을 마련하는데 도움이 될 것이다.

• 한국콘텐츠학회논문지
• /
• 제21권8호
• /
• pp.236-246
• /
• 2021

이 연구의 목적은 고교학점제도의 운영 방향을 탐색하여 고교학점제도의 문제점들을 해결하고 고교학점제도를 효과적·효율적으로 운영하도록 도움을 주는 것이다. 연구방법은 문헌연구로 문헌연구대상은 선행연구, 공청회자료, 언론보도자료, 2015개정교육과정, 교육부의 고교학점제 추진방안 등이다. 연구 결과 고교학점제도의 문제점을 해결하기 위한 교육과정 편성의 기본적인 방향은 첫째, 보통 교과 과목 위주로 편성해야 한다. 둘째, 자신이 원하는 분야의 관련 과목을 깊이 있게 학습할 수 있게 해야 한다. 셋째, 교육과정 편성의 근거도 확인해야 한다. 고교학점제도 문제점 중 진로지도를 위한 고교학점제도 운영 방향은 첫째, 진로 학습·코칭을 위한 진로 교육과정위원회 구성 및 운영이다. 둘째, 교원의 업무 체계 재 구조화이다. 셋째, 진로 희망 설계 및 진학 방향 탐색의 시간 마련이다. 넷째, 진로 및 학업 설계 지도 코칭 북 제공이다. 다섯째, 진로 및 학업 설계 지도 교사의 역할이다. 여섯째, 과목 선택에 대한 책임감 강조 및 재 이수 프로그램 마련이다.

• 한국콘텐츠학회논문지
• /
• 제9권4호
• /
• pp.286-298
• /
• 2009

전통적 형사법체계에서 범죄피해자는 실체적 진실을 파악하기 위한 심리의 대상으로 전락되어, 범죄로 인하여 인간의 기본적인 인권을 침해당했음에도 불구하고 범죄피해자의 권리는 간과되고 말았다. '잊혀진 존재' 또는 '주변적인 존재'에 불과 하던 범죄피해자에 대한 피해자학의 연구과제는 형사법체계에서 범죄 피해자가 인격적 자율성과 인간의 존엄성을 향유하는 것일 것이다. 우리나라에서 피해자에 대한 논의가 처음 등장한 것은 헨티히(Hans Von Hemtig)가 1948년 피해자 연구의 필요성을 역설한지 23년이 지난 후이며 최근에 와서 '범죄피해자 구조법', '성폭력범죄의 처벌 및 피해자 보호 등에 관한 법률', '범죄피해자 보호법'등 범죄피해자의 인권보장과 보호를 위한 제도의 보완이 계속되어 왔다. 그러나 현실에서 보면 제한적 범죄 내에서 피해자 보호를 위한 제도적 장치를 마련하는 성과가 있었지만 현실적인 권리 구제와 보호는 아직 미흡하다고 생각한다. 이에 본 연구는 범죄피해자의 초상권 보호 개념을 살펴보고, 그 문제점과 현행 구제 제도를 검토하여 그 개선방안을 찾고자 한다.

• Membrane and Water Treatment
• /
• 제2권3호
• /
• pp.175-185
• /
• 2011

Ultrafiltration is an emerging technology for drinking water treatment because it produces better water quality as compared with conventional treatment systems. More recently, the combination of UF technology with other processes in order to improve its performance has been observed. These associations aim to maximize the contaminants removal and reduce membrane fouling. The operational performance of contaminants removal and water production of two UF pilot plants was compared. The first plant (Guarapiranga) was fed with raw water and the second plant (ABV) with pre-treated water by the coagulation, flocculation and sedimentation processes at Alto da Boa Vista WTP (Sao Paulo, Brazil). Both units operated continuously for approximately 2,500 hours, from September/2009 to January/2010. The results showed that the ABV UF pilot plant was able to operate at higher specific fluxes (6.2 $L.d^{-1}.m^{-2}.kPa^{-1}$ @ $25^{\circ}C$) than Guarapiranga (3.1 $L.d^{-1}.m^{-2}.kPa^{-1}$ @ $25^{\circ}C$). However, the number of chemical cleanings conducted in both pilot units during the considered operation period was the same (4 chemical cleanings for each plant), which shows that the pre-treatment reduced the membrane fouling. The water quality at ABV for all the variables analyzed was better, but the feed water quality was also better due to pretreatment. The rejection values for the different contaminants were higher at Guarapiranga mainly because of a pollution load reduction after pre-treatment at ABV. Even with the better performance of the ABV UF pilot plant, it is necessary to take into consideration the complexity of the complete treatment system, and also the costs involved in the construction and operation of a full-scale treatment unit.