• Journal of Aquaculture
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• v.13 no.3
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• pp.267-275
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• 2000

To evaluate the characteristics and efficiency of oxygen transfer rate of a polystyrene foam bead as media in a packed column aerator was tested. This media has more surface area and cheaper than other ordinary plastic media. The polystyrene foam media was a sphere-shaped bead with 2.5 mm in diameter and specific surface area was 1,350 $m^2$/$m^3$. Oxygen transfer rate and standard aeration efficiency were tested under different hydraulic loading rates, depths of the media and temperatures. Experiment 1 was performed using a small packed column aerator with 10 cm in diameter and 1 m in length. The aerator filled with 0, 4.5, 9.0 and 18.0 cm of the media was tested under hydraulic loading rates of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperatures of 20, 25 and 3$0^{\circ}C$, respectively. In this experiment, standard oxygen transfer rate (SOTR) increased with the hydraulic loading rate and depth of the media increased. The maximum SOTR was reached at 5.6 $m^3$/$m^2$/min of hydraulic loading rate with 9 cm in depth of the media. However, standard aeration efficiency (SAE) decreased with the hydraulic loading rate increased because electricity consumed by pump increased as hydraulic loading rate increased. The highest SAE was reached at hydraulic loading rate of 2.0 $m^3$/$m^2$/min with 9.0 cm in depth of the media. Therefore, the highest SOTR and SAE were achieved at 9.0 cm in depth of the media regardless of the hydraulic loading rate. The maximum SAE was about 1.8 kg $O_2$/kW-hr with the hydraulic loading .ate of $m^3$/$m^2$/min at temperature of 20 $^{\circ}C$.Experiment 2 was performed using a larger aerator, 20 cm in diameter with 2 m in height. The aerator filled with 0, 9, 18, 27 and 36 cm of the media was operated under hydraulic loading rate of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperature of 27 $^{\circ}C$. The SAE reached to the highest efficiency (1.9 kg $O_2$/kW-hr) at 2.0 $m^3$/$m^2$/min of hydraulic loading rate and 36 cm in depth of the media. According to the above results, the polystyrene foam bead as a media in a packed column aerator was effective to increase oxygen transfer rate.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.219-224
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• 2006

3 차원 입력 장치는 키보드나 마우스 같은 일반적인 입력 장치로는 받아 들이기 어려운 3 차원 입력을 사용자로부터 간편하고 직관적인 방법으로 받아들일 수 있다는 측면에서 활발히 연구 및 사용되고 있다. 또한 햅틱 장치는 가상 물체의 조작에 따른 시각적인 피드백 외에 가상 물체의 느낌을 피드백 힘을 통해 사용자에게 전달해 줌으로써 컴퓨터와 사용자간의 상호 작용에 큰 도움을 준다. 본 논문은 햅틱 피드백이 적용된 실시간 가변형 모델과 효과적인 3 차원 입력에 대한 기반 연구를 하고자 한다. 그리고 이에 대한 한 가지 사례로써 햅틱 장치를 이용한 가상 판화 시스템을 제작 한다. 가상 판화 시스템은 시각 처리 부분과 촉각 처리 부분, 그리고 사용자의 3 차원 입력을 돕는 인터페이스 부분으로 구성되어 있다. 시각 처리 부분은 3 차원 공간 상에서 사용자의 조각에 따른 판화 표면의 변형을 처리하며 촉각 처리 부분은 실제 판화를 제작할 때 느끼는 촉각을 햅틱 인터페이스를 이용하여 사용자에게 전달한다. 이를 위해 먼저 시각 처리 부분에서는 NURBS 기반의 자유 형상 변형 (FFD)기법을 이용하였는데 가상 조각도에 의한 물체 표면의 지역적인 변형을 구현하기 위해 조각도가 닿는 부분에 대해 기조 격자점 (control point)을 증가시켜 원하는 부분에 대한 지역적인 변화를 용이하도록 하였고 다음으로 촉각 처리 부분에서는 S-chain 모델을 이용하였는데 S-chain 모델을 객체 전체에 적용하지 않고 접촉이 일어날 경우 그 접촉점을 기준으로 S-chain 모델을 지역적으로 적용하는 방법을 고안하여 실제 구현에 이용하였다. 인터페이스 적인 측면에서 사용자의 3 차원 입력장치를 통한 인터렉션은 사용자로 하여금 보다 자유로운 입력을 허용하지만 이에 따른 깊이 지각 문제를 발생시킨다. 이러한 문제를 최소화 시키고 사용자의 깊이 지각을 강화시키기 위해 사용자에게 제공되는 시각적 자극을 변형시키고 다양한 정보를 제공하도록 하였다. 가상 판화 시스템은 가상 환경에서 사용자의 조작에 따른 다양한 결과물을 제작 및 출력해 볼 수 있도록 해준다. 또한 가상 환경에서 이러한 기반을 제공함으로써 가상 환경의 장점인 복사, 이동 및 영구 보존 특성을 동시에 얻을 수 있다. 본 논문은 이러한 작업을 위한 기반 기술로써 햅틱 및 가변형 모델, 3 차원 입력 장치에 대한 시각적 인터페이스에 대해 다루고 이 기반 기술을 바탕으로한 가상 판화 시스템의 구현에 대하여 논하고자 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.809-818
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• 2007

Generally, carriers on which microwave circuits are mounted are used as building blocks of MIC module for the convenience of MIC assembly and the unit module characterization. However the interconnection of the microstrip-based carriers by wire bonding causes the serious problem of mismatch and results in the higher insertion loss as frequency becomes higher. The gap and the depth between carriers are considered as the main reason of the degradation. The CPW can be the solution to cope with such problem considering its field are dominantly concentrated on the top plane. In this paper, we propose and demonstrate the CBFGCPW to microstrip transition with the low insertion loss that can be applied without causing the MIC carrier interconnection problem.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.128-128
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• 2016

Cu 배선폭 미세화 기술은 반도체 디바이스의 성능 향상을 위한 핵심 기술이다. 현재 배선 기술은 lithography, deposition, planarization등 종합적인 공정 기술의 발전에 따라 10x nm scale까지 감소하였다. 하지만 지속적인 feature size 감소를 위하여 요구되는 높은 공정 기술 및 비용과 배선폭 미세화로 인한 재료의 물리적 한계로 인하여 배선폭 미세화를 통한 성능의 향상에는 한계가 있다. 배선폭 미세화를 통한 2차원적인 집적도 향상과는 별개로 chip들의 3차원 적층을 통하여 반도체 디바이스의 성능 향상이 가능하다. 칩들의 3차원 적층을 위해서는 별도의 3차원 배선 기술이 요구되는데, TSV(through-Si-via)방식은 Si기판을 관통하는 via를 통하여 chip간의 전기신호 교환이 최단거리에서 이루어지는 가장 진보된 형태의 3차원 배선 기술이다. Si 기판에 $50{\mu}m$이상 깊이의 via 및 seed layer를 형성 한 후 습식전해증착법을 이용하여 Cu 배선이 이루어지는데, via 내부 Cu ion 공급 한계로 인하여 일반적인 공정으로는 void와 같은 defect가 형성되어 배선 신뢰성에 문제를 발생시킨다. 이를 해결하기 위해 각종 유기 첨가제가 사용되는데, suppressor를 사용하여 Si 기판 상층부와 via 측면벽의 Cu 증착을 억제하고, accelerator를 사용하여 via 바닥면의 Cu 성장속도를 증가시켜 bottom-up TSV filling을 유도하는 방식이 일반적이다. 이론적으로, Bottom-up TSV filling은 sample 전체에서 Cu 성장을 억제하는 suppressor가 via bottom의 강한 potential로 인하여 국부적 탈착되고 via bottom에서만 Cu가 증착되어 되어 이루어지므로, accelerator가 없이도 void-free TSV filling이 가능하다. Accelerator가 Suppressor를 치환하여 오히려 bottom-up TSV filling을 방해한다는 보고도 있었다. 본 연구에서는 유기 첨가제의 치환으로 인한 TSV filling performance 저하를 방지하고, 유기 첨가제 조성을 단순화하여 용액 관리가 용이하도록 하기 위하여 suppressor만을 이용한 TSV filling 연구를 진행하였다. 먼저, suppressor의 흡착, 탈착 특성을 이해하기 위한 연구가 진행되었고, 이를 바탕으로 suppressor만을 이용한 bottom-up Cu TSV filling이 진행되었다. 최종적으로 $60{\mu}m$ 깊이의 TSV를 1000초 내에 void-free filling하였다.

• Journal of Korean Society of Steel Construction
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• v.30 no.2
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• pp.105-114
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• 2018

The use of post installed anchors with bond type has lately been increasing when it is necessary to repair, reinforce, or remodel structures. This method provides flexibility and simplicity for construction of structural members that require adhering or fixing. Meanwhile, strength evaluation of anchors with expansion type among post-installed anchors systems has nearly reached setting up stage like design code through continual experimental studies for the last ten years, but analyses or experimental studies on anchor system with bond type are not yet sufficient. Accordingly, the designers and builders of korea depend on foreign design codes since there are no exact domestic design code they could credit. In this study, the objectives are investigating the effects on pull-out strength of resin anchors embedded into plain concrete by pull-out experiment of resin anchors with variables such as anchor diameter, anchor interval, embedment depth and edge distance.

• Journal of the Korean Geotechnical Society
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• v.19 no.3
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• pp.5-13
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• 2003

The soil nailing is one of the useful support-system in urban excavation because of the presence of other structures in the vicinity Since the soil nailing system was introduced, model experiments and theoretical studies have been performed to investigate behavior of soil nailed wall. However, there are few data in the case of multi-layered soil strata just like Seoul Metropolitan area in Korea. The feed back analyses are carried out using the measured wall displacement data for soil nailing construction sites with multi-layered strata in order to analyze the distance and the coefficients of extension zone of ground behind soil nailed wall. As a result, the distance of extension zone increased with increasing of the final excavation depth and the ratio of the distance to the final excavation depth was shown to be about 94% of the final excavation depth. Also, the coefficients of extension zone increased with enlargement of soil layer thickness and converged into constant value of 1.05. On the other hand, the maximum vertical displacements by the feed back analysis and Caspe's method were shown to be approximately 80%, 150~280% of the maximum horizontal displacement respectively.

• Journal of the Korea Society of Computer and Information
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• v.24 no.11
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• pp.179-185
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• 2019

In this paper, We purpose the basic data for the success of effective CPR using mirror in order to increase the quality of chest compression during CPR. The subject of this study was an experimental study based on a randomized crossover design of 28 people who completed the BLS Health Care Provider, and collected data were analyzed by SPSS Ver. 23.0 for Win statistics program. As the research methods, depth, speed, compression to relaxation ratio, arm angle and easiness during the chest compression were measured. Taken together, the results of this study showed that using a mirror-based chest compression method for chest compressions in adult CPR could make chest compressions easier, in addition, the quality of breast compression was improved by improving the posture of the rescuers, such as the average depth of compression, compression to relaxation ratio, and arm angle. However, it is necessary to confirm the feasibility of clinical application through additional studies on various environmental factors and job groups for mirror-based chest compression method.

• The Journal of the Korea Contents Association
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• v.8 no.12
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• pp.222-235
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• 2008

This study looks at motivations of video UCC users as a member of creative class. A qualitative research method was used for analyzing data collected by interviews. Killing time users, active clickers and creators are distinguished as different types of UCC users and their differing motivations are explored. The findings of the study are as follows: First, information sharing, self presentation, communication needs, ease of use for self presentation, usefulness are expressed as motivating factors for both active clickers and creators, Pleasure motivates every type of users. However, content creators experience a specific type of pleasure which is the pleasure of creativity or flow, which this study highlights as a key driving factor for content creators. The study adds to the findings of UCC user research which applies the TAM and the PAD model by revealing what pleasure and flow specifically mean for different types of UCC users.

• Education of Primary School Mathematics
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• v.26 no.2
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• pp.83-97
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• 2023

Nominalization is one of the grammatical metaphors that makes it easier to mathematize the target that needs to be converted into a formula, but it has the disadvantage of making problem understanding difficult due to complex and compressed sentence structures. To investigate how this nominalization affects students' problem-solving processes, an analysis was conducted on 233 third-grade elementary school students' problem solving of eight arithmetic word problems with or without nominalization. The analysis showed that the presence or absence of nominalization did not have a significant impact on their problem understanding and their ability to convert sentences to formulas. Although the students did not have any prior experience in nominalization, they restructured the sentences by using nominalization or agnation in the problem understanding stage. When the types of nominalization change, the rate of setting the formula correctly appeared high. Through this, the use of nominalization can be a pedagogical strategy for solving word problems and can be expected to help facilitate deeper understanding.

• Progress in Medical Physics
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• v.5 no.2
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• pp.57-68
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• 1994

Purpose : The purposes are to discuss the reason to measure dose distributions of circular small fields for stereotactic radiosurgery based on medical linear accelerator, finding of beam axis, and considering points on dosimetry using home-made small water phantom, and to report dosimetric results of 10MV X-ray of Clinac-18, like as TMR, OAR and field size factor required for treatment planning. Method and material : Dose-response linearity and dose-rate dependence of a p-type silicon (Si) diode, of which size and sensitivity are proper for small field dosimetry, are determined by means of measurement. Two water tanks being same in shape and size, with internal dimension, 30${\times}$30${\times}$30cm$^3$ were home-made with acrylic plates and connected by a hose. One of them a used as a water phantom and the other as a device to control depth of the Si detector in the phantom. Two orthogonal dose profiles at a specified depth were used to determine beam axis. TMR's of 4 circular cones, 10, 20, 30 and 40mm at 100cm SAD were measured, and OAR's of them were measured at 4 depths, d$\sub$max/, 6, 10, 15cm at 100cm SCD. Field size factor (FSF) defined by the ratio of D$\sub$max/ of a given cone at SAD to MU were also measured. Result : The dose-response linearity of the Si detector was almost perfect. Its sensitivity decreased with increasing dose rate but stable for high dose rate like as 100MU/min and higher even though dose out of field could be a little bit overestimated because of low dose rate. Method determining beam axis by two orthogonal profiles was simple and gave 0.05mm accuracy. Adjustment of depth of the detector in a water phantom by insertion and remove of some acryl pates under an auxiliary water tank was also simple and accurate. TMR, OAR and FSF measured by Si detector were sufficiently accurate for application to treatment planning of linac-based stereotactic radiosurgery. OAR in field was nearly independent of depth. Conclusion : The Si detector was appropriate for dosimetry of small circular fields for linac-based stereotactic radiosurgery. The beam axis could be determined by two orthogonal dose profiles. The adjustment of depth of the detector in water was possible by addition or removal of some acryl plates under the auxiliary water tank and simple. TMR, OAR and FSF were accurate enough to apply to stereotactic radiosurgery planning. OAR data at one depth are sufficient for radiosurgery planning.