Earticle

We reported on annealing effect on Ga₂O₃/Al₂O₃/SiC devices grown by radio frequency sputtering method. Post-deposition annealing at 900 ℃ was performed, which results in crystallization in the Ga₂O₃ films. The major peaks (-401) and (403) of Ga₂O₃ which was thermally treated at 900 ℃ appears in the x-ray diffraction (XRD) results. Auger electron spectroscopy (AES) shows that Ga and Al atoms seems to be diffused into the opposite direction Al₂O₃ and Ga₂O₃ after annealing. Transfer and output characteristics of back-gate transistor were analyzed where SiC substrate is used as gate material. On-state current and on/off ratio increased almost 10⁹ and 10⁶ times higher in the 900 ℃ annealed sample.

Despite otherwise advantageous properties, the performance and reliability of devices manufactured in β-Ga₂O₃ on semi-insulating Ga₂O₃ substrates may degrade because of poorly mitigated self-heating, which results from the low thermal conductivity of Ga₂O₃ substrates. In this work, we investigate and compare self-heating and device performance of β-Ga₂O₃ MESFETs on substrates of semi-insulating Ga₂O₃ and 4H-SiC. Electron mobility in β-Ga₂O₃ is negatively affected by increasing lattice temperature, which consequently also negatively influences device conductance. The superior thermal conductivity of 4H-SiC substrates resulted in reduced β-Ga₂O₃ lattice temperatures and, thus, mitigates MESFET drain current degradation. This, in turn, allows practically reduced device dimensions without deteriorating the performance and improved device reliability.

In this study, we measured and comparatively analyzed the characteristics of MPS (Merged Pin Schottky) diodes in 4H-SiC by changing the areal ratio between the Schottky and PN junction region. Increasing the temperature from 298 K to 473 K resulted in the threshold voltage shifting from 0.8 V to 0.5 V. A wider Schottky region indicates a lower on-resistance and a faster turn-on. The effective barrier height was smaller for a wider Schottky region. Additionally, the depletion layer became smaller under the influence of the reduced effective barrier height. The wider Schottky region resulted in the ideality factor being reduced from 1.37 to 1.01, which is closer to an ideal device. The leakage saturation current increased with the widening Schottky region, resulting in a 1.38 times to 2.09 times larger leakage current.

In this work, we fabricated oxide on an n-type silicon substrate through local anodic oxidation (LAO) using atomic force microscopy (AFM). The resulting oxide thickness was measured and its correlation with load force, scan speed and applied voltage was analyzed. The surface oxide layer was stripped using a buffered oxide etch. Ohmic contacts were created by applying silver paste on the silicon substrate back face. LAO was performed at approximately 70% humidity. The oxide thickness increased with increasing the load force, the voltage, and reducing the scan speed. We confirmed that LAO/AFM can be used to create both lateral and, to some extent, vertical shapes and patterns, as previously shown in the literature.

Recently, in Korea, single- or two-person households (50.5%) are becoming the primary family type due to increasing divorce rates, population aging, personal code of values and so on. Hence, small families will lead to a sudden increase of single- or two-person households. People searching for small houses are increasing because of the provision of officetels, one room and urban-life housing as well as economic recession. However, this has led to habitability problems, such as parking, storage space and decline in safety. In this study, we obtain the proper contents from LQI indicators of advanced research and use the indicators to evaluate the residential environment quality. We conduct a post-occupancy-evaluation (POE) survey and compare the habitability satisfaction level of apartment and officetel residents. According to the survey, officetel residents' satisfaction levels are low for the following factors in the order listed: ventilation, storage space, management expenses and facilities for children and the elderly.

최근 건설 시공 업무가 다양화되고 현장이 대형화됨에 따라 현재 건설현장의 시스템으로는 모든 상황을 실시간으로 관리하고 모니터링 하는데는 한계가 있어 이에 대한 체계적인 계측관리 방안이 요구되어 지고 있다. 이에 본 연구에서는 USN 기술 중 건설현장에 적용할 때 가장 중요한 USN기술 중 하나인 네트워크 기술을 선정하였다. 도출한 요소들을 바탕으로 각 요소들의 쌍대비교를 통해 각 기준에 따른 요소들의 중요도를 산정하였다. 산정한 중요도를 종합하여 각 기준 및 상황을 고려하여 의사결정 지원모델 매트릭스를 작성을 통해 건설현장 토공사 계측 시 고려사항에 따른 중요도를 정량적으로 평가하여 의사결정을 지원할수 있는 모델을 제시하였다. 본 연구의 결과는 건설현장 토공사 계측관리를 위해 USN기술 적용 시 상황에 맞는 기술을 선택 할 수 있는 판단의 기준 및 척도로 활용이 가능하며, USN기술 도입을 통해 현장의 지능화 및 관리 효율 극대화를 가져올 것으로 기대한다.

Recently, construction work has diversified and become larger. So, a systematic measurement and management measures are required. In this study, USN technology which is one of the most important network technologies was selected. Based on elements derived from comparison of each element of standard was calculated according to the importance of the elements. The importance of the decision to support the proposed model is explained by integrating the importance of each criteria and decision-support model by considering the situation and creating a matrix of considerations for the construction of earthwork. The results of this study show that USN technology in the context of judging criteria can be selected for the earthwork.

본 논문에서는 온도보상 자기회로를 갖는 집중정수형 아이솔레이터를 설계하고 전자계 시뮬레이션을 통한 최적 파라미터를 이용하여 각각 K-PCS, GSM1900, W-CDMA, WiBro 대역의 이동통신 중계기용 아이솔레이터를 제작하였으며 IMD 특성을 평가하였다. 결과로서 K-PCS 대역의 경우에 Insertion loss와 Return loss는 각각 0.2dB 이하, 25dB이상, Isolation 23dB에서 대역폭은 30MHz이었고 GSM1900의 경우에는 각각 0.25dB, 23dB, Isolation 30 dB에서 대역폭은 60 MHz이었으며 W-CDMA의 경우에는 각각 0.15dB, 25dB, Isolation 24.8 dB테서 대역폭은 60 MHz이었다. 또한 WiBro 대역의 경우에는 각각 0.25dB, 23dB 이상, Isolation 22.1dB에서 대역폭은 100MHz이었고 IMD측정 결과는 $76.4dBc{\sim}80.1dBc$이었으며 기존의 제품에 비하여 우수한 특성을 가지고 있음을 확인하였다.

The lumped element isolators with temperature compensation magnetic circuits were designed in this paper. Isolators for mobile repeater at each band of K-PCS, GSM1900, W-CDMA, WiBro were fabricated by using optimum parameters of EM simulation, Form the results of this study, first of all, insertion loss at K-PCS band was below 0.2 dB and return loss was over 25dB. The bandwidth in isolation 23dB was found 30 MHz. Secondly, the figures of both losses at GSM1900 were 0.25dB and 23dB, respectively. The measured bandwidth in isolation 30dB was 60MHz. Thirdly, the losses at W-CDMA band were 0.15dB and 25dB. The bandwidth in isolation 24.8dB was found 60Mhz. Finally, the figures of both losses at Wibro band were 0.25dB and 23dB, respectively. The measured bandwidth in isolation 22.1dB was 100Mhz. In addition, the results of measured IMD were shown from 76.4dBc to 80.1dBc.

본 연구에서는 GSM1900 주파수 대역을 위한 이동통신 기지국용 Isohybrid를 개발함으로써 시스템의 효율을 증가시켰으며 제품의 소형화 및 안정된 특성을 구현하였다. 결과로서 각각 Chip coupler type과 Hybrid coupler type의 Isohybrid transmitter combiner를 설계 및 제작하였고 Insertion loss는 Chip coupler type Isohybrid의 경우에 $3.29\;dB{\sim}3.47\;dB$로 측정되었으며 Hybrid coupler type의 경우에는 $3.17\;dB{\sim}3.42\;dB$로 측정되어 3.5 dB 미만을 만족하였다. ANT단과 Port단 사이의 Isolation은 Chip coupler type Isohybrid의 경우에 $24.23\;dB{\sim}29.98\;dB$로 측정되었으며 Hybrid coupler type의 경우에는 $26.28\;dB{\sim}36.91\;dB$로 측정되어 23 dB 이상의 우수한 특성을 확인하였다.

Total efficiency of transmitter system was improved by developing combinational 2-Way Isohybrid for GSM1900 base station in this paper. The size of product was decreased and the characteristics were stabilized. The isohybrid transmitter combiner of chip coupler type and hybrid coupler type were designed and fabricated. Insertion loss for chip coupler type isohybrid was $3.17\;dB{\sim}3.47\;dB$. On the other hand, insertion loss for hybrid coupler type was $3.17\;dB{\sim}3.42\;dB$. Isolations between ANT and port were $24.23\;dB{\sim}29.98\;dB$ in case of chip coupler type Isohybrid and were $26.28\;dB{\sim}36.91\;dB$ in case of hybrid coupler type, respectively.

CP (Cellular Phone) is currently one of the most attractive technologies and RT (Robot Technology) is also considered as one of the most promising next generation technology. We present a new technological concept named RCP (Robotic Cellular Phone), which combines RT and CP. RCP consists of 3 sub-modules, $RCP^{Mobility}$, $RCP^{Interaction}$, and $RCP^{Integration}$. $RCP^{Interaction}$ is the main focus of this paper. It is an interactive emotion system which provides CP with multi-emotional signal receiving functionalities. $RCP^{Interaction}$ is linked with communication functions of CP in order to interface between CP and user through a variety of emotional models. It is divided into a tactile, an olfactory and a visual mode. The tactile signal receiving module is designed by patterns and beat frequencies which are made by mechanical-vibration conversion of the musical melody, rhythm and harmony. The olfactory signal receiving module is designed by switching control of perfume-injection nozzles which are able to give the signal receiving to the CP-called user through a special kind of smell according to the CP-calling user. The visual signal receiving module is made by motion control of DC-motored wheel-based system which can inform the CP-called user of the signal receiving through a desired motion according to the CP-calling user. In this paper, a prototype system is developed for multi-emotional signal receiving modes of CP. We describe an overall structure of the system and provide experimental results of the functional modules.

In this paper, developed isolator for gap filler is analyzed and designed using the simulation tool. Using the designed parameters, isolator is fabricated and tested in gap filler band. Temperature characteristics of isolator depend on magnet, YIG ferrite, and conductor etc. These require temperature stability and possible method of compensation for the temperature dependent effects. The temperature stabilization tries to use Ni-alloy. Developed isolator that compare with room temperature and high temperature characteristics has change fewer than 20 MHz. Implemented isolator shows more than 20 dB isolation characteristic at center frequency(2,650 MHz) and has 0.2 dB insertion loss in overall 100 MHz operating bandwidth. Return losses of input and output port are measured below -20 dB.

최근 이 기종 시스템 및 애플리케이션의 상호호환을 위해 웹 기반 서비스에 대한 관심이 고조되어가고 있다. 웹의 편리함과 동시에 누구에게나 접근 가능한 웹의 개방성은 보안에 대한 문제점을 야기시키는데, 웹서비스 보안기술은 이에 대한 해결책을 제시하고 있다. 본고에서는 웹서비스 보안기술에 대해 살펴보고, 웹서비스 보안 기술의 취약점 및 이를 보완할 수 있는 향상방안에 대해 기술하고자 한다.

만성 림프구성 백혈병은 오랜기간에 걸쳐서 발전하는 전신질환이며, 급성 백혈병에서 보이는 것보다 더욱 성숙되고 잘 분화된 림프구가 혈액과 골수에 존재하는 것을 특징으로 한다. 본 증례보고에서는 발작, 복수의 임상 증상과 전염성 성병성 종양에 대한 치료경력이 있는 2년령의 거세된 잡종견을 다루고 있다. 여러 가지 진단 절차를 통하여 만성 림프구성 백혈병으로 진단내렸고, chlorambucil과 prednisolone을 이용한 항암치료를 현재까지 적용해 오고 있다. 초기내원 시 보였던 대부분의 증상에 대한 개선을 볼 수 있었으며, 환자의 삶의 질은 향상되었다.

Chronic Iymphocytic leukemia is a general disease that evolves over a longer duration and is characterized by more mature and well-differentiated Iymphocytes in blood and bone marrow than those seen in acute leukemia. This report presents a 2-year-old mix neutered male dog with seizure, ascites, and transmissible venereal tumor. Diagnostic works-up concluded chronic Iymphocytic leukemia. Chemotherapy composed of chlorambucil and prednisolone has been applied to the patient until now. Remission of almost manifestations was achieved, and the quality of life improved.

In order to promote CO gas sensitivity, $SnO_2$ added ZnO prepared. The electrical conductivities and dielectric constants decreased by increasing $SnO_2$ content in air. The electrical conductivities in 1000ppm CO atmosphere were larger than in dry air. The measured CO sensitivities were $1{\sim}15.2$ at $100^{\circ}C{\sim}480^{\circ}C$. The maximum CO sensitivity of 15mol% $SnO_2$ added ZnO was 15.2 at $305^{\circ}C$.