• Journal of Acupuncture Research
• /
• 제31권2호
• /
• pp.21-30
• /
• 2014

Objectives : Manufacturing and manipulation techniques of acupuncture can be interpreted as an induced electromagnetic viewpoint, as proposed in previous study. Considering from this point of view, the magnetization of needles should be essential to enhance the electromagnetic effects during the behavior of the acupuncture needling. Methods : The current disposable needles are made of non-magnetic stainless steels, so ferromagnetic materials were searched as suitable substitutes. Meanwhile, at the practical view, stainless steels are very available for the several superior properties like as corrosion resistance, strength, etc., magnetic stainless steels were first investigated. Some types of them still preserved the ferromagnetic properties of iron, so trial needles were made with them. And then magnetization of them were followed. Results : Among the hundreds types of stainless steels, martensitic or ferritic ones are ferromagnetic. The needles made with these ferromagnetic wires were magnetized, and polarized by magnetizer, and their magnetic properties were improved. Moreover, in addition to the superiority of the magnetism, the electrical and thermal conductivities of them were even better than those of the current austenitic stainless steels. Conclusions : Through the developmental study based on the electromagnetic viewpoint, the magnetized and polarized acupuncture needles were completed. This means that these needles having improved magnetism can be used to improve the electromagnetic needling effects, and moreover, their superiorities in the electrical and thermal conductivities can also give another benefits in treatments of electrical or warm needling.

• Bulletin of the Korean Chemical Society
• /
• 제26권11호
• /
• pp.1783-1789
• /
• 2005

Modeling of a steam generator crevice in a nuclear power system needs to take into account both thermalhydraulic and chemical phenomena. As a first step towards developing a reliable model, a chemical equilibrium model was developed to predict chemical speciation in a magnetite-packed crevice by adopting the “tableau” method. The model was benchmarked with the available experimental data and the maximum deviation did not exceed two orders of magnitude. The developed model was applied to predict the chemical speciation in a magnetite-packed crevice. It was predicted that caustic environment was developed by the concentration of NaOH and the dissolution of magnetite. The model indicated that the dominant aqueous species of iron in the caustic crevice was $FeO_2\;^-$. The increase of electrochemical corrosion potential observed in the experiment was rationalized by the decrease of dissolved hydrogen concentration due to a boiling process. It was predicted that under the deaerated condition magnetite was oxidized to hematite.

• 상하수도학회지
• /
• 제28권4호
• /
• pp.441-451
• /
• 2014

The flushing is important to maintain good water quality in water main. It is a technique of using water velocity to remove sediments in water distribution system. The variety of water quality problems can occur in a distribution system, so too can a variety of benefits be gained by system flushing. In order to effectively perform the flushing, the contaminants to be removed to set up and it can be solved, it is necessary to ensure the proper flow rate. In this study, the removal of contaminants present in the inner water pipe attached loose deposits such as fine particles of granular activated carbon, sand and iron corrosion product sought to derive flow rates. Thus, the constant observation of using pilot plant scale water distribution plant for the movement of floating characteristics of particles were assessed.

• 상하수도학회지
• /
• 제24권6호
• /
• pp.735-741
• /
• 2010

A pilot test was carried out to investigate the long term operation characteristics of Microfiltration (MF) system as a pretreatment for seawater reverse osmosis (SWRO) processes for two years. A commercialized MF module with pressurized operation type was used to filter seawater to remove particles which can foul reverse osmosis (RO) membrane. Silt Density Index (SDI) values of filtered seawater by the MF system were ranged from 0.14 to 1.79, which meet the SDI standard for RO feed water as depicted in previous literatures. Although the tested seawater is quite clean (i.e., dissolved organic cabon (DOC) concentration and turbidity were about 1 mg/l and less than 1 NTU, respectively) enough not to foul the MF membrane, steep increase in trans-membrane pressure (TMP) with a constant flux were observed over a whole operation period. A set of operation and water analysis data implies that the steep increase in TMP was resulted from iron and maganese fouling by the combination of metal corrosion by seawater and oxidation state by aeration and residual chlorine.

• Tribology and Lubricants
• /
• 제30권1호
• /
• pp.21-28
• /
• 2014

Damage to the cylinder liner of large ship engines, such as scuffing on the surface, can occur very easily because it is operated in a corrosive environment. This scuffing may be due to oil film destruction and corrosive wear caused by water and sulfur included in the fuel, abrasive impurities, and poor lubricants. Thus, a method for monitoring the condition and diagnosing the failure of the cylinder liner and piston ring is needed. In this study, a reciprocating friction and wear test was carried out with a cast iron specimen, which simulated an engine cylinder in a corrosive atmosphere. The lubricants used were base oil, stirred oil with distilled water, a NaCl solution, and dilute sulfuric acid. The friction coefficient and frequency spectrum were measured using a load cell and acceleration sense in each experimental condition. We then used these results to diagnose the failure of the cylinder liner.

• 상하수도학회지
• /
• 제28권5호
• /
• pp.589-600
• /
• 2014

Tuberculation and slime accumulated in water mains play an important role in modifying water quality of drinking water. Therefore, in this study, it was investigated that what materials were accumulated, and what components were included in the tuberculation and slime of water mains. The Various tuberculation and slime sample were collected from the 12 water mains to analyze their physical and chemical properties and crystal structure. As a analysis method, VSS(Volatile suspended solid), SEM(scanning electron microscope), EDS(Energy Dispersive X-ray spectroscope), ICP(Inductively Coupled Plasma Mass Spectrometer) and XRD(X-Ray Diffractomete) were used. The results of analysis on the samples, the representative materials were verified such as iron corrosion products, the fine sand particles generated during backwash, fine particles of activated carbon, aluminum used in coagulation process, and manganese included in raw water.

• Journal of Mechanical Science and Technology
• /
• 제15권3호
• /
• pp.327-338
• /
• 2001

This paper presents the results of a structural analysis to determine design variables such as the inner basket array type, and thicknesses of the outer shell, and lid and bottom of a spent nuclear fuel disposal canister. The canister construction type introduced here is a solid structure with a cast iron insert and a corrosion resistant overpack, which is designed for the spent nuclear fuel disposal in a deep repository in the crystalline bedrock, entailing an evenly distributed load of hydrostatic pressure from the groundwater and high swelling pressure from the bentonite buffer. Hence, the canister must be designed to withstand these high pressure loads. Many design variables may affect the structural strength of the canister. In this study, among those variables, the array type of inner baskets and thicknesses of outer shell and lid and bottom are attempted to be determined through a linear structural analysis. Canister types studied hear are one for the pressurized water reactor (PWR) fuel and another for the Canadian deuterium and uranium reactor (CANDU) fuel.

• 한국산학기술학회논문지
• /
• 제14권6호
• /
• pp.2612-2617
• /
• 2013

본 연구에서는 스틸 헤어커터와 비교하여 절삭성, 내식성 내마모성이 우수하고 생체친화성이 뛰어난 소재인 지르코니아($ZrO_2$)를 원료로 하는 헤어커터 개발을 위하여 설계, 성형, 소결, 연마가공 최적화를 통해 두께 0.253mm의 초박형 지르코니아 커터를 제작하였다. 커터 시편을 전자주사현미경(SEM)으로 관찰한 결과, 성형성과 절삭면 가공이 양호한 것으로 나타났으며, 절단시험을 통해 상품성이 충분한 것으로 평가되었다. 본 지르코니아 커터 가공기술 연구결과를 이용하여 면도기, 여성용 제모기, 눈썹정리기 등 고부가가치 미용기구 개발에 활용 될 수 있다.

• 한국주조공학회지
• /
• 제36권1호
• /
• pp.18-23
• /
• 2016

Iron based amorphous ribbons with the nominal compositions of $(Fe_{79}C_{11}B_8Si_2)_{100-X}Cr_X$ (X = 0,2,4,6,8 at%) have been developed as reinforcements that can be applied to the concrete materials. Mechanical properties and glass forming ability of the ribbons can be enhanced by the optimum amounts of Cr additions that can also improve corrosion properties of the ribbons. Vein patterns typical of the fractured surface morphology of amorphous alloys have been observed on the surfaces of ribbons after tensile tests. It is inferred from the EDS analysis results of vein patterns that carbon segregations occur within the narrow shear band regions.

• 한국지반공학회논문집
• /
• 제20권2호
• /
• pp.47-58
• /
• 2004

강관은 Northridge 지진이 발생했을 당시 산사태가 일어나는 언덕이나 산악지역에 매설되어 있었다. 본 논문은 지리정보체계(GIS) 시스템에서 위치에 따라 강관을 서로 다른 유형별로 분류하고 정의하였다. 이 논문은 지반속도와 강관의 손상관계를 분석하고 Northridge 지진 시 발생한 산사태의 영향을 받았던 지역을 조사하였다. 하나의 주목할 만한 사실은 Northridge 지진 후 강관의 손상률이 다른 종류의 매설관, 특히 캐스트아이런(CI)보다 더 높았다는 것이다. Northridge 지진으로 인한 상대적으로 높은 강관의 손상률은 가장 큰 내부압력을 요하는 곳에서의 설치관례와 부식으로 인한 영향으로 해석될 수 있다.