• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.99-104
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• 2024

With the advancement of power electronics technology and the increasing demand for high-efficiency power semiconductors, silicon carbide (SiC) devices have gained attention as an alternative to overcome the limitations of traditional silicon (Si) semiconductors. SiC devices enable excellent switching efficiency due to their high switching speed. However, parasitic inductance within the power module can cause voltage oscillations and overshoot phenomena, potentially leading to issues with electrical reliability and efficiency. To address these challenges, two approaches were proposed and validated. The first approach involved applying an RC snubber circuit to mitigate the effects of parasitic inductance, thereby improving electrical stability. The second approach focused on optimizing the lead-frame design to reduce parasitic inductance. Both methods were verified through simulations and experiments, demonstrating that the electrical reliability and efficiency of SiC power modules can be simultaneously improved.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.81-89
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• 2012

The concrete-filled tubular square column is superior to steel frame column in terms of fire resistance because of the thermal storage provided by the concrete. Studies have been conducted on CFT column reinforcement with steel bars or with the use of an internal tube to improve its structural load capacity and fire resistance. In fact, reinforced CFT columns have been increasingly used to deal with high axial force. The functional deterioration of columns due to fire damage needs to be measured precisely. In this study, the temperature distribution inside the columns in case of a fire was evaluated and the degree of deterioration in the load capacity of the concrete and reinforcing members associated with temperature distribution was identified in order to evaluate the overall residual strength of the columns.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.563-569
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• 2004

The DNA sequence of the chitosanase gene (choK) from $\beta$-Proteobacterium KNU3 showed an 1,158-bp open reading frame that encodes a protein of 386 amino acids with a novel 74 signal peptide. The degenerated primers based on the partial deduced amino acid sequences from MALDI- TOF MS analyses yielded the 820 bp of the PCR product. Based on this information, double inverse PCR cloning experiments, which use the two specific sets of PCR primers rather than single set primers, identified the unknown 1.2 kb of the choK gene. Subsequently, a 1.8 kb of full choK gene was cloned from another PCR cloning experiment and it was then subcloned into pGEM T-easy and pUC18 vectors. The recombinant E. coli clone harboring recombinant pUC18 vector produced a clear halo around the colony in the glycol chitosan plates. The recombinant ChoK protein was secreted into medium in a mature form while the intracellular ChoK was produced without signal peptide cleavage. The activity staining of PAGE showed that the recombinant ChoK protein was identical to the chitosanase of wild-type. The comparison of deduced amino acid sequences of choK revealed that there is 92% identity with that of Sphingobacterium multivorum chitosanase. Judging from the conserved module in other bacterial chitosanases, chitosanase of KNU3 strain (ChoK) belongs to the family 80 of glycoside hydrolases.

• Journal of Korean Neurosurgical Society
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• v.49 no.2
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• pp.97-101
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• 2011

Objective : It is technically difficult to treat wide-necked intracranial aneurysms by the endovascular method. Various tools and techniques have been introduced to overcome the related technical limitations. The purpose of this study was to evaluate the radiologic and clinical results of widenecked intracranial aneurysm treatment using the endovascular method. Methods : Fifteen aneurysms in 15 patients were treated by the endovascular method from October 2009 to August 2010. Seven patients presented with subarachnoid hemorrhage (SAH), seven patients had unruptured aneurysms, and one patient had an intracerebral hemorrhage and intraventricular hemorrhage due to an incompletely clipped aneurysm. The mean dome-to-neck ratio was 1.1 (range, 0.6-1.7) and the mean height-to-neck ratio was 1.1 (range, 0.6-2.0). We used double microcatheters instead of a stent or a balloon for the first trial. When we failed to make a stable coil frame with two coils, we used a stent-assisted technique. Results : All aneurysms were successfully embolized. Eleven aneurysms (73%) were embolized by the double microcatheter technique without stent insertion, and four aneurysms (27%) were treated by stent-assisted coil embolization. One case had subclinical procedure-related intraoperative hemorrhage. Another case had procedure-related thromboembolism in the left distal anterior cerebral artery. During the follow-up period, one patient (7%) had a recanalized aneurysmal neck 12 months after coil embolization. The recurrent aneurysm was treated by stent-assisted coil embolization. Conclusion : We successfully treated 15 wide-necked intracranial aneurysms by the endovascular method. More clinical data with longer follow-up periods are needed to establish the use of endovascular treatment for wide-necked aneurysm.

• Journal of architectural history
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• v.17 no.3
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• pp.61-80
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• 2008

The purpose of this study is to discover the characteristics and the change of the framed structure with triple beam. 61 existing buildings with the triple beam structure were selected and analyzed extensively. The result of this study could be described in detail like below. The triple beam structure is used in the highly graded and symbolized building like the Buddhist sanctum and the Confucian sanctum. And the triple beam structure was chiefly used in $1600{\sim}1800's$. Generally, 1 Koju-type with Toikan(退間) is applied to the triple beam structure. Despite of the sameness of framed structure, there is a tendency that the rear Toikan(後退間) is used in the Buddhist sanctum and the front Toikan(前退間) is used in the Confucian sanctum. This different application of the Toikan(退間) resulted from the different spatial characteristics which reflect function and grade of the building. The application of Sangjungdori(上中道里, upper purlin) and two Danyeon(短椽, short rafter) is a necessary consequence, because Jungbo(중보, middle beam) is located between Daebo(대보, beam) and Jongbo(종보, small and high located beam) as an additional member of frame. And these are essential characteristics of the framed structure with triple beam. The triple beam structure is formed in a transitional period, as the result from eliminating the inner high-column from the 2 Koju and double beam structure. Though the Daebo is longer, the structure is more stable. But the rate of application of the triple beam structure is low, because it does not exceed the double beam structure in merits. Some of buildings with the triple beam structure has the asymmetrical characteristic in design, which is appeared in the latter period of Joseon Dynasty.

• Journal of architectural history
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• v.21 no.1
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• pp.171-186
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• 2012

The objective of this study is to find out the recent trends of hanok design based on 58 hanoks appeared in architecture magazines in the last 10 years. The cases are analyzed in terms of location, size, building form, spatial organization, material, roof form, and the ceiling form of living room. The consequences of this study is as follows; Most of the recent hanoks are built in rural area (91.4%), which shows the hanok is not accepted as an urban house type. Hanoks tend to be built in 2 stories whose 2nd floor is smaller than the 1st floor. (34.5%) The preferred size is total floor area of $99.2{\sim}165.2m^2$ (62.0%), 3 rooms (46.6%) with a traditional ondol room (60.3%). The buildings with ㄱ-shape (43.1%) and linear-shape (27.6%) are preferred, and the compact plan type similar with apartment house appears (13.8%). In the roof design that greatly influences the appearance of building, the traditional design factors such as half-hipped roof (55.2%), double eaves (27.6%), and eaves curve tend to be sustained. In terms of spatial organization, most of recent hanoks have double-layed plan (74.2%). The living room mostly has separately defined space. (82.8%) The indoor and outdoor tend to be connected by a narrow wooden veranda (39.7%), while some cases don't have any wooden floor space (48.3%). The entrance is adopted as an important spatial element in front part of building (75.9%), and it influences the appearance of building. The living room, the counterpart of the wooden floor hall in traditional hanok, and kitchen tend to be interiorized. In terms of material, the cement roof tile and red clay brick are preferred. Consequently, the walls of recent hanoks have the image of brick structure rather than the wooden frame structure of traditonal hanok.

• Steel and Composite Structures
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• v.36 no.5
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• pp.507-519
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• 2020

Double skin composite walls are increasingly popular and have been applied to many safety-related facilities. They come from the concept of composite slabs. Conventional connectors such as shear studs and binding bars were used in previous studies to act as the internal mechanical connectors to lock the external steel faceplates to the concrete core. However, the restraint effects of these connectors were sometimes not strong enough. In this research, a recently proposed unique type of steel truss was employed along the wall height to enhance the composite action between the two materials. Concrete-filled tube columns were used as the boundary elements. Due to the existence of boundary columns, the restraints of steel faceplates to the concrete differ significantly for the walls with different widths. Therefore, there is a need to explore the effect of height-to-width ratio on the structural behavior of the wall. In the test program, three specimens were designed with the height of 3000 mm, the thickness of 150 mm, and different widths, to simulate the real walls in practice. Axial compression was applied by two actuators on the tested walls. The axial behavior of the walls was evaluated based on the analysis of test results. The influences of height-to-width ratio on structural performance were evaluated. Finally, discussion was made on code-based design.

• Journal of the Korean housing association
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• v.17 no.2
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• pp.125-134
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• 2006

The tightness of windows have devoted to the improvement of thermal insulation and energy saving in buildings. But it is known that this tightness causes some side effects such as low ventilation, low capacity to humidity and temperature control and these are not profitable for inhabitants. To act on these side effects, Korean traditional windows which are composed of Han-Ji(Koreand traditional paper) and Chang-Sal(Korean traditional wooden frame) have been studied to get a reasonable solutions for these problems. In this study, to compare the thermal and humidity control performance of current window(12 mm pair) and Korean traditional windows, frames which are made of existing window and Korean traditional windows are adapted to scale model house and then humidity and temperature of in and out of scale model house are measured and analysed. The results of this study are followings ; 1) When Korean traditional window charges 20cm(1/8 of total window area) from total window area, Han-Ji window has higher thermal insulation than that of existing window in daytime. There is the most big thermal difference when double faced with double-ply Han-Ji window is placed to mock-up house. In night-time, the temperature difference is very small so this means that Korean traditional window is good to cover direct sunlight in daytime and reduce the temperature of balcony. One faced with one-ply han-Ji window has the best humidity penetration performance among three type of Korean traditional windows. 2) When Korean window area enlarged to 40cm(1/4 of total window area), the function of 40cm width Han-Ji window is higher than that of 20cm's. This means that enlargement of Han-Ji window cover direct sunlight more and is more efficient in humidity penetration.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.1
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• pp.92-98
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• 1997

In this paper, the results of the measurement and analysis of extremely low freqency(ELF) eletric field in the vicinity of 154[kV] overhad transmission lines have been described. The planar-type electric field sensor has been fabricated by three dimensional structure with special consideration of taking the power frequency and lower components. The calibration experiments have been carried out according to the procedures of IEEE recommendation. The electric field measuring system has the frequency bandwidth of 7[Hz] to 2.7[MHz] and the response sensitivity of 0.094[mV/V/m]. Also the practical measurements of electric field under an 154[kV] double corcuit overhead transmission lines have been made abd abalyzed. It was known that the lateral electric field profiles under an 154[kV] double circuit overhead transmission lines show the asymmetrical distributions owing to the environmental metal frame structures and their maximum electric field magnitude is less than 3[kV/m]. It can be concluded that the measured results of the electric fields satisfy with all limits or guide -lines of the various authorized international institutes' recommendations.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.1
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• pp.14-23
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• 1997

In this paper, the results of the measurement and analysis of extremely low frequency(ELF) electric field in the vicinity of 154[kV] overhead transmission lines have been described. The planar-type electric field sensor has been fabricated by three dimensional structure with special consideration of taking the power frequency and lower components. The calibration experiments have been carried out according to the procedures of IEEE recommendation. The electric field measuring system has the frequency bandwidth of 7[Hz] to 2.7[MHz] and the response sensitivity of 0.094[mV/V/m]. Also the practical measurements of electric field under an 154[kV] double circuit overhead transmission lines have been made and analyzed. It was known that the lateral electric field profiles under an 154[kV] double circuit overhead transmission lines show the asymmetrical distributions owing to the environmental metal frame structures and their maximum electric field magnitude is less than 3[kV/m]. It can be concluded that the measured results of the electric fields satisfy with all limits or guidelines of the various authorized international institutes' recommendations.