• 전자공학회논문지 IE
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• 제46권4호
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• pp.25-30
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• 2009

용광로는 외피 부분에 내부 내화물의 온도를 낮추기 위하여 냉각수를 공급하는 냉각판 또는 스테이브를 사용하고 있다. 주변 조업 조건의 열악으로 냉각수를 공급하는 배관의 부식으로 냉각수가 내화물에 침투하여 내화물의 수명을 떨어뜨리고, 노황을 악화시키는 원인이 되고 있다. 이에 본 연구는 용광로 냉각설비장치에 이상 현상이 발생하였을 때 위치를 정확히 확인함에 따라 신속하게 누수된 부위를 파악하여 대처할 수 있는 기능을 갖춘 냉각관 누수 자동감지장치를 개발하였다. 주된 연구는 전자제어 장치인 마이크로프로세서를 응용한 전자변 제어장치를 이용하여 냉각설비의 파손으로 발생되는 누수현상으로 인한 고열과 분진 일산화탄소 등의 산출로 작업환경의 재해를 자동방지 하고자 하였으며, 작업환경이 친환경적이며 작업의 가치를 재창출할 수 있는 방법들이 연구되고 있다. 용광로 분위기의 일산화탄소 자동 감지장치와 그에 따른 출력신호를 자동 전송하는 무선중계기 장치를 개발함으로 용광로 냉각설비 장치의 분위기 작업환경을 수동방식에서 무인자동화방식으로 개선하였다.

• 유통과학연구
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• 제8권3호
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• pp.5-15
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• 2010

Business corporations have become specialized and on the basis of various interests try to strengthen their competitiveness through a cooperative system of purchase, distribution, service and IT technology. And an advanced Internet-based electronic commerce has witnessed explosive growth and a business-to-business (B2B) electronic commerce. Through E-marketplace. business corporations achieve such diverse utilities as expenditure curtailment, process reduction and prime cost reduction. And with business depression worldwide and soaring prices of materials, many business corporations consider the introduction of comprehensive purchase of MRO (maintenance, repair and operation) materials. The Purpose of this study was to examine the definition of B2B E-marketplace and the utilities of MRO commerce correctly focusing on an empirical analysis of cases of MRO supply and purchase business corporations. The indications acquired from this research results are as follows. Firstly, as for MRO integrated purchase under the characteristics of the market environment, it had to use the supplier obligatorily through the integrated purchase on the level of CEO's decision-making or the group rather than the voluntary will of the purchasing department or the procurement department. Secondly, as for the present B2B E-marketplace MRO purchase, the purchasing agency business has formed the mainstream, but it is aiming at the diversification of the benefit by supplementing/correcting the business model such as category type, mediation business type, MRO-type advancing in the store inclusive of the purchasing agency business, keeping pace with the potential market of MRO. Thirdly, as for analysis of the products, the purchaser wants more various products and assortment of goods than those of the present time, and also to be provided with the precise product information. Especially, as the importance of the product sourcing becomes high, the whole energy has been bestowed on acquirement of the excellent suppliers. Fourth, as for use of B2B E-marketplace MRO integrated purchasing system, there are the purchasing companies complaining the inconvenience even until now, and there is the demerit spending the long time during the image move and the process treatment. It shall try to shorten the searching time and the process treatment time as the system is centered on the purchaser. In order to enhance the efficiency of MRO E-marketplace purchase, followings must be considered: First, because the importance of product sources ever increases, an excellent supplier must be secured earnestly. Second, the time of process must be reduced focusing on purchasers. B2B E-marketplace will increase and diversify electronic commerce continuously. Through MRO E-marketplace, business corporations will reduce expenditure, achieve a transparent and speedy trade, and purchase products of fine quality, thus establishing a most effective market. In addition, in this study the investigator brings focus into MRO which has not been clearly discussed in the academic and business world so far and intensively highlights an indirect material-oriented expenditure curtailment effect. By taking all the aspects of supplier, purchaser and practical economical value into account, the investigator presents a strategic direction for the successful comprehensive purchase of B2B MRO.

• 보건행정학회지
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• 제5권2호
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• pp.35-69
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• 1995

The managerial environment of hospitals in Korea characterized by low levels of medical insurance fees is worsening by increasing government regulations as to the utilization of medical services, rising costs of labor, material, and medical equipments, growing patient expectations concerning the quality of services, and escalating competitions among large hospitals in the market. Hospitals should seek for their survival strategies in this harsh environment and they should have information about costs of their products in doing so. However, it has not been available due to the complexity of the production process of hospital services. The objectives of this study were to develop a service-based cost accounting model and to apply the developed model to a study hospital to obtain cost information of hospital services. A model commonly used for the job-order product cost accounting in the manufacturing industry was modified for the use in hospitals in Korea. Actual costs, instead of standard costs, incurred to produce a unit of services during a given period of time were estimated in the model. Data required to implement the model included financial information, statistics for the allocation of supportive cost center costs to final cost centers, statistics for the allocation of final cost center costs to services, and the volume of each services charged to patients during a study period. The model was executed using data of a university teaching hospital located in Seoul for the fiscal year 1992. Data for financial information, allocation statistics fo supportive service costs, and the volume of services, most of them in electronic form, were available to the study. Data for allocation statistics of final cost center costs were collected in the study. There were 15 types of evaluation and management service, 2, 923 types of technical service, and 2, 608 types of drug and material service charged to patients in the study hospital during the fiscal year 1992. Labor costs of each of seven types of pesonnel, material costs of 611 types of drugs and materials, and depreciation costs of 212 types of medical equipments, miscellaneous costs, and indirect costs incurred in producing a unit of each services were estimated. Medical insurance fees for basic services such as evaluation and management of inpatients and outpatients, injection, and filling prescriptions, and for operating procedures were found to be set lower than costs. Infrequent services which use expensive medical equipments showed negative revenuse as well. On the other hand, fees for services not covered by the insurance such as CT, MRI and Sonogram, and for laboratory tests were higher than costs. This study has a significance in making it possible for a hospital to obtain cost information for all types of services which produced income based on all types of expenses incurred during a given period of time. This information can assist the management of a hospital in finding an effective cost reduction strategy, an efficient service-mix strategy under a given fee structure, and an optimum strategy for within-hospital resource allocations.

• 새물리
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• 제68권12호
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• pp.1315-1323
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• 2018

본 연구에서는 폐 커피분말을 열처리 조건에 따른 탄화과정을 거쳐 리튬 이온 이차전지의 음극 활물질 재료로 응용하기 위한 실험을 진행하였다. 이차전지의 음극 활물질로 사용한 커피분말은 커피 껍질이 아닌 커피 알맹이로부터 얻은 것으로, 커피를 내리고 남은 커피분말을 공기 중에서 건조하고 $Ar/H_2$ 분위기에서 열처리하여 기공(pore)이 있는 활성 탄소 분말 형태로 얻을 수 있었다. 전기화학적인 특성을 조사한 결과 약 0.2 V에서 Li의 삽입, 0.01 V에서 Li의 탈리가 관찰되었다. $700^{\circ}C$에서 열처리된 시료에 대해 1000 mA/g의 전류밀도로 1000 사이클 충방전 후 측정된 비용량은 303 mAh/g 이었으며 99.5% 이상의 쿨롱(Coulomb) 효율을 나타내었다. 폐 커피분말을 이용한 리튬이온이차전지는 기공으로 인한 표면적 증가와 이온 및 전자전도 특성 개선으로 전기화학적인 성능 향상을 보였으며, 또한 재활용을 통한 전지 제조 가격을 낮출 수 있는 이점이 있다.

• Journal of Magnetics
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• 제7권3호
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• pp.63-71
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• 2002

Three fabrication techniques for forming thin barrier layer with uniform thickness and large barrier height in magnetic tunnel junction (MTJ) are discussed. First, the effect of immiscible element addition to Cu layer, a high conducting layer generally placed under the MTJ, is investigated in order to reduce the surface roughness of the bottom ferromagnetic layer, on which the barrier is formed. The Ag addition to the Cu layer successfully realizes the smooth surface of the ferromagnetic layer because of the suppression of the grain growth of Cu. Second, a new plasma source, characterized as low electron energy of 1 eV and high density of $10^{12}$ $cm^{-3}$, is introduced to the Al oxidation process in MTJ fabrication in order to reduce damages to the barrier layer by the ion-bombardment. The magnetotransport properties of the MTJs are investigated as a function of the annealing temperature. As a peculiar feature, the monotonous decrease of resistance area product (RA) is observed with increasing the annealing temperature. The decrease of the RA is due to the decrease of the effective barrier width. Third, the influence of the mixed inert gas species for plasma oxidization process of metallic Al layer on the tunnel magnetoresistance (TMR) was investigated. By the use of Kr-O$_2$ plasma for Al oxidation process, a 58.8 % of MR ratio was obtained at room temperature after annealing the junction at $300{^{\circ}C}$, while the achieved TMR ratio of the MTJ fabricated with usual Ar-$0_2$ plasma remained 48.4%. A faster oxidization rate of the Al layer by using Kr-O$_2$ plasma is a possible cause to prevent the over oxidization of Al layer and to realize a large magnetoresistance.

• 한국전자파학회논문지
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• 제23권3호
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• pp.343-354
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• 2012

본 논문에서는 무선 전력 전송을 위한 다양한 스파이럴 구조의 영자 공진기들을 설계하였다. 메타 물질 전송 선로의 영차 공진은 무한 파장의 특징을 가지기 때문에 공진기의 크기에 상관없이 디자인이 가능한 장점을 가진다. 또한, 무선 전력 전송에서 고효율의 전송 효율을 얻기 위해서는 공진기의 Q-factor와 공진기간의 결합 계수가 커야 한다. 따라서 제안된 영차 공진기들은 영차 공진을 유도하기 위해 스파이럴 형태의 인덕터와 집중 캐패시터 소자를 사용하였고, parametric study와 R, L, C 회로 분석을 통해 높은 Q-factor를 얻기 위한 최적의 디자인을 찾고자 하였다. 최적화된 공진기들은 기존의 스파이럴 공진기와 모의 실험을 통해 비교되었으며, 최적화된 공진기들 중 제작된 공진기의 크기는 $20cm{\times}20cm{\times}8cm$($0.009{\lambda}_0{\times}0.009{\lambda}_0{\times}0.004{\lambda}_0$)이고, 13.56 MHz 대역의 주파수와 40 cm 거리에서 80 %의 전송 효율이 측정되었다.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.60-63
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• 2012

Enhancement of efficiency and luminance of organic light-emitting diodes was investigated by the introduction of a lithium carbonate ($Li_2CO_3$) electron-injection layer. Electron-injection layer is used in organic light-emitting diodes to inject electrons efficiently between a cathode and an organic layer. A device structure of ITO/TPD (40 nm)/$Alq_3$ (60 nm)/$Li_2CO_3$ (x nm)/Al (100 nm) was manufactured by thermal evaporation, where the thickness of $Li_2CO_3$ layer was varied from 0 to 3.3 nm. Current density-luminance-voltage characteristics of the device were measured and analyzed. When the thickness of $Li_2CO_3$ layer is 0.7 nm, the current efficiency and luminance of the device at 8.0 V are improved by a factor of about 18 and 3,000 compared to the ones without the $Li_2CO_3$ layer, respectively. The enhancement of efficiency and luminance of the device with an insertion of $Li_2CO_3$ electron-injection layer is thought to be due to the lowering of an electron barrier height at the interface region between the cathode and the emissive layer. This is judged from an analysis of current density-voltage characteristics with a Fowler-Nordheim tunneling conduction mechanism model. In a study of lifetime of the device that depends on the thickness of $Li_2CO_3$ layer, the optimum thickness of $Li_2CO_3$ layer was obtained to be 1.1 nm. It is thought that an improvement in the lifetime is due to the prevention of moisture and oxygen by $Li_2CO_3$ layer. Thus, from the efficiency and lifetime of the device, we have obtained the optimum thickness of $Li_2CO_3$ layer to be about 1.0 nm.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.128.1-128.1
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• 2016

Nitrided-metal gates on the high-${\kappa}$ dielectric material are widely studied because of their use for sub-20nm semiconductor devices and the academic interest for the evanescent states at the Si/insulator interface. Issues in these systems with the Si substrate are the electron mobility degradation and the reliability problems caused from N defects that permeates between the Si and the $SiO_2$ buffer layer interface from the nitrided-gate during the gate deposition process. Previous studies proposed the N defect structures with the gap states at the Si band gap region. However, recent experimental data shows the possibility of the most stable structure without any N defect state between the bulk Si valence band maximum (VBM) and conduction band minimum (CBM). In this talk, we present a new type of the N defect structure and the electronic structure of the proposed structure by using the first-principles calculation. We find that the pair structure of N atoms at the $Si/SiO_2$ interface has the lowest energy among the structures considered. In the electronic structure, the N pair changes the eigenvalue of the silicon-induced gap state (SIGS) that is spatially localized at the interface and energetically located just above the bulk VBM. With increase of the number of N defects, the SIGS gradually disappears in the bulk Si gap region, as a result, the system gap is increased by the N defect. We find that the SIGS shift with the N defect mainly originates from the change of the kinetic energy part of the eigenstate by the reduction of the SIGS modulation for the incorporated N defect.

• 한국항해학회지
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• 제23권1호
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• pp.23-28
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• 1999

With a rapid progress in electronic industry we enjoy various conveniences of life. As many kinds of information equipments are supplied even to most of individuals as to be called an information society, we are exchanging much information with one another surprisingly. Consequently the occupation density of microwave frequency band is highly increased, and electromagnetic environment is getting more seriously bad. It often gives fatal blow to even human life and thus becomes serious social problems. Electromagnetic wave absorbers for anechoic chamber are needed to broaden the effective frequency bandwidth, reduce the thickness, and decrease the weight. There are various absorbers proposed for the above conditions, but they could not decisively solve it the alone requirements. The Electromagnetic wave absorber made by a conventional ferrite tile has, for example, broadened the useful frequency bandwidth by the way of forming air layer(practically use urethane foam, etc.) on the ferrite tile. Therefore, an air layer is formed between a reflection plate and a sintered Ni-Zn ferrite tile of 7 mm in thickness, which has reflectivity less than -20 dB from 30 MHz to 400 MHz in bandwidth. Accordingly, in this paper, a broadened electromagnetic wave absorber are designed, which has the reflection characteristics less than -20 dB from 30 MHz to 6,000 MHz in the bandwidth. Then we achieved the goal by design the inserting square Ferrite Cylinders with the thickness less than 17.5 mm on existing grid type Ferrite absorber. The purpose of this research is on the development of very wide-band electromagnetic absorber for a universal anechoic chamber for measuring radiated electromagnetic wave or immunity of electronic equipments, GTEM-cell, wall material for preventing TV ghost, etc.

• 한국전자파학회논문지
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• 제23권6호
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• pp.752-755
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• 2012

본 논문은 타이어 휠로 인한 전파의 감쇄를 최소화하기 위해 직각 스파이럴 형태의 TPMS용 송신 안테나를 설계하고 제작하였다. 설계된 안테나의 433 MHz 주파수에서의 $S_{11}$은 시뮬레이션 결과, -10 dB 대역폭이 23 MHz(427~450 MHz)가 확보되었으며, 설계된 안테나를 두께 0.3 mm인 황동 재질로 $5mm(W){\times}23mm(D){\times}10mm(H)$의 크기로 제작한 후 반사 손실을 측정한 결과, -10 dB 대역폭이 433 MHz${\pm}$10 MHz로 충분한 대역폭이 확보됨을 확인하였다. 제작된 안테나의 방사 전력은 휠에 미부착시 -44.21 dBm, 휠에 장착 시 -50.0 dBm으로 측정되었으며, 실제 데이터 송수신 테스트를 통해 실용화가 가능함을 확인할 수 있었다.