• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.5
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• pp.481-487
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• 2005

Proposed induction-heated system is innovative system which applied special high-frequency power circuit technique for thermal converse technique and IH(Induction-Heating) magnetic induction heating generated from induction-heated metallic package that is for distillation unit. In this occurs not burning, so that the working environment can be improved. This electromagnetic induction heating technique is used high frequency inverter, By using high frequency inverter high frequency alternative current in the range of [kHz] can be made with conventional alternative current. In this contribution IGBT module is used for high frequency inverter. This paper proposes new fluid heating method. Which is operated as follows. Working coil, which is wrapped outside of pipeline, makes the eddy current. Inside of heating vessel in isolated pipeline the specially designed stainless metallic package is inserted, which can be heated by eddy current losses. And then In this paper are discussed action analysis and characteristics analysis of 5[kW] class full-bridge resonant inverter system and resonant metallic package. In addition, by using this system, how high-efficiency heater is developed and application of system are also discussed.

• Resources Recycling
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• v.2 no.4
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• pp.1-9
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• 1993

A study on the recovery of nitric and hydrofluoric acids is carried out with pulsed column extractor in order to the industrial application of this process. Firstly, from the continuous experiments about the recovery of acids using domestic stainelss steel pickling solution, it is found out that the free nitric and hydrofluoric acids are only extracted by 70% TBP and the heaby metals such as Fe, Cr and Ni are not extracted. The effectiveness of extraction and stripping generally improves as the pulse velocity(product of amplitude and frequency) is increased, optimum performance typically occuring slightly below an amplitude-frequency product which results in flooding the column because of excessive emulsification. When the pickling solution is treated by 70% TBP at a phase ratio of A/O=1/2 in the extraction and by distilled water at a phase ratio of O/A=1 in the stripping, the concentration of refined acides are 102g/$\ulcorner$ $HNO_3$and 8.8g/$\ulcorner$ HF, respectively and the recovery of $HNO_3$and HF are 90.7% and 75.2%, respectively.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.235-240
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• 2009

Crystlline silicon solar cells markets are increasing at rapid pace. now, crystlline silicon solar cells markets screen-printing solar cell is occupying. screen-printing solar cells manufacturing process are very quick, there is a strong point which is a low cost. but silicon and metal contact, uses Ag & Al pates. because of, high contact resistance, high series resistance and sintering inside process the electric conductivity decreases with 1/3. and In pastes ingredients uses Ag where $80{\sim}90%$ is metal of high cost. because of low cost solar cells descriptions is difficult. therefore BCSC(Buried Contact Solar Cell) is developed. and uses light-induced plating, ln-line galvanization developed equipments. Ni/Cu matel contact solar cells researches. in Germany Fraunhofer ISE. In order to manufacture high-efficiency solar cells, metal selections are important. metal materials get in metal resistance does small, to be electric conductivity does highly. efficiency must raise an increase with rise of the curve factor where the contact resistance of the silicon substrate and is caused by few with decrement of series resistance. Ni metal materials the price is cheap, Ti comes similar resistance. Cu and Ag has the electric conductivity which is similar. and Cu price is cheap. In this paper, Ni/Cu/Ag metal contact cell with screen printing manufactured, silicon metal contact comparison and analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.37-41
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• 2020

In this paper, we propose a routing method to improve the message transmission efficiency between DTN nodes in an environment where communication infrastructure in the city is destroyed. In the situation where a certain size of communication infrastructure can not function, the message transmission process between the nodes is explained. An effective routing method for improving reliability between nodes was proposed and evaluated using DTN simulator. The routing algorithm with improved reliability in urban areas was confirmed by simulation considering the message transmission relationship between nodes on uncertain path due to the destruction of communication infrastructure. We used a routing algorithm that includes all the contact information the node has experienced in the past. In the simulation of delivering messages in a situation where the communication infrastructure was destroyed, relatively better results were obtained than the existing routing algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.113-120
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• 2010

RFID system is the contact-less recognition technology and use for distribution system, environment, transport, security and so on. However, it may create many security relevant problems such as privacy because constraints of RFID communication environment. So several methods of resolving these problems have been proposed. Recently, Shin and Park proposed an efficient RFID authentication protocol with protecting user's privacy using hash function and exclusive-OR.. But Ahn and Bu et al. poia problem that a attacker can to masquerade as malicious reader because their protocol can't providing mutual authentication.nted out weakness of Shin and Park's protocol and proposed more secure and efficient protocol. Unfortunately, Ahn and But's protocol has In this paper, We propose an improved RFID authentication protocol providing mutual authentication. The proposed protocol has advantages that providing mutual authentication between a tag and a reader, secure against replay attack and spoofing attack. Also, it guarantees anonymity of RFID tag and secure against location tracking attack by collusion of malicious readers.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.285-291
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• 2014

This paper is related to the improvement of efficiency for high performance centrifugal pumps by reducing leakage loss, which is achieved by applying the grooved seal as a non-contact seal to the pumps. Various combinations of grooved seal types, including the spiral and the parallel groove in the rotor and/or in the stator, were tested by the experiment. And the corresponding hydraulic performance and the magnitude of axial thrust were measured and calculated for ten cases. From the results, the type with the spiral groove(spiral angle : $0.98^{\circ}$) in both the rotor and the stator was found to be most effective. In this case, the head and the efficiency were improved from the original design by 2.1% and 2.3% respectively at design capacity($340m^3/h$), and the axial thrust was decreased by 10%.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.279.1-279.1
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• 2014

글래스(glass), 폴리머 또는 쿼츠와 같은 투명기판은 렌즈, 디스플레이, 광검출기, 광센서, 발광다이오드 및 태양전지와 같은 광 및 광전소자 분야에서 널리 사용되고 있다. 이러한 소자들의 경우, 광추출 또는 광흡수 효율을 향상시키는 것이 매우 중요하다. 그러나 투명기판의 경우, 약 1.5의 굴절율로 인해 표면에서 4% 반사가 발생되는데, 이러한 광학적 손실은 소자의 성능을 저하시키는 원인이 된다. 따라서, 글래스와 공기 경계면에서 발생되는 광손실을 줄이기 위한 효율적인 무반사 코팅이 필요하다. 최근, 우수한 내구성 뿐만 아니라, 광대역 파장 및 다방향성에서 무반사 특성을 보이는 서브파장 주기를 갖는 나노구조(subwavelength structures)의 형성 및 제작 공정에 관한 연구가 보고되고 있다. 이러한 나노구조는 경사 굴절율 분포를 가지는 유효 매질을 형성하기 때문에 투명기판 표면에서의 Fresnel 반사로 인한 광손실을 줄일 수 있다. 또한, 무반사 서브파장구조를 형성하기 위한 패터닝 방법으로, 간단/저렴하고 대면적 제작이 용이한 열적 응집 공정을 이용한 자가정렬된 금속 나노입자 형성 기술이 널리 사용되고 있다. 따라서 본 실험에서는 열적 응집현상에 의해 형성된 비주기적 금 나노입자 식각 마스크 패턴 및 유도결합 플라즈마 장비를 이용하여 글래스 기판 위에 무반사 서브파장 나노구조를 제작하였다. 금 나노패턴 및 제작된 글래스 서브파장 나노구조의 식각 프로파일은 주사전자현미경을 사용하여 관찰하였으며, UV-Vis-NIR 스펙트로미터를 사용하여 빛의 투과율을 측정하였다. 또한, 제작된 샘플들에 대해서, 표면 접촉각 측정 장비를 이용하여 표면 wettability를 조사하였다.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.929-936
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• 2013

The saturator and injection nozzle are important facilities on the dissolved air flotation process. To increase the formation of micro bubble, it is required to improve the air dissolving performance in the saturator and keep the pressure uniform from the saturator to the nozzle. This study aimed to evaluate the performance of the saturator and the hydraulic effect of the nozzle and the pipe structure. The air volume concentration, bubble size and bubble residual time were measured in the test. The saturator, which had mounted with the spray nozzle, showed a good performance for bubble formation. Also, the characteristics of micro bubble formation were influenced by pressure uniformity and flow velocity through the orifice in the nozzle.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.373-379
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• 2010

EMAT has been applied in various fields for flaw detection and material characterization because it has noncontact property in wave generation and a good mode selectivity. Unfortunately, however, EMAT shows low signal to noise ratio relative to commercial contact transducer because of low energy conversion efficiency. If the phase matching through the control of time delay between each coil consisting of the array EMAT is accomplished, it is expected that it will be a solution for the improvement of low signal to noise ratio. In this experiment, the phased array EMATs which consists of 3 or 4 meander coils and one big magnet were fabricated for surface and vertical shear wave generation. Effect of phased delay control on signal directivity and amplitude enhancement was verified. A slit with the depth of 0.5 mm and a side-drill hole of 0.5 mm diameter were clearly detected by fabricated phased array EMATs, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.195-202
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• 2011

RFID(Radio Frequency IDentification) is a system to identify objects and its usage is being extended to distribution, healthcare, and air&port etc. RFID is a contactless system environment, and reducing tag authentication time is important because multiple tags are identified at the same time. Studies about RFID system so far is, however, mostly to improve security vulnerability in the tag authentication process. Therefore, this paper suggests an efficient scheme to decrease the time of tag authentication which is also safe for the security of tag authentication process. The proposed scheme cuts down on the tag ID search time because it searches only the classified relevant ID in the database, which is one of many components of RFID system, by using identification bits for tag ID search. Consequently, the suggested scheme decreases process time for tag ID authentication by reducing the processing time and the load of the database. It also brings performance improvement of RFID system as it improves the energy applicability of passive tag.