• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.60-67
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• 1999

Micro-fabrication techniques such as lithography and LIGA processes usually require large investment and are suitable for mass production. Therefore, there is a need for a new micro-fabrication technique that is flexible and more cost effective. In this paper a novel, economical and flexible method of producing micro-pattern on silicon wafer is presented. This method relies on selective removal of mask by mechanical cutting. Then micro-pattern is produced by chemical etching. V-shaped grooved of about 3 ${\mu}m$ wide and 2 ${\mu}m$ deep has been made on ${SiO_2}m$ coated silicon wafer with this method. This method may be utilized for making microstructures in MEMS application at low cost.

• 대한생식의학회:학술대회논문집
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• 1999.05a
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• pp.45-52
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• 1999

포유동물의 수정은 정자가 난자내로 침입함으로써 시작되는데 이때 정자는 부계의 유전물질 이외에도 다양한 후성적 요소들 (epigenetic factors), 즉 난활성 인자, 중심체, 부계 유래의 mitochondria 및 부계 특이 삽입 유전자 등을 난자에 전달해 준다. 하지만 수정 및 초기 배발달동안 정자에 의해 전달된 후성적 요소들의 역할과 기능적 발현 및 억제 기전에 관해서는 명확히 알려져 있지 않다. 수정보조기법인 ICSI 및 ROSI의 개발은 남성불임치료에 혁신적인 기술로 자리잡고 있을 뿐만 아니라 포유동물의 수정과정을 이해 하는데 많은 도움을 주고 있다. 본 연구실에서는 최근 몇 년간 돼지난자에 정자, 다양한 정자 구성 요소들, 정낭세포, 및 이종의 정자 등을 미세주입하여 수정을 유도한 후 핵질 및 세포질의 변화과정과 배 발달과정을 살펴 봄으로써, 수정시 정자에 의해 전달되는 후성적 요소들의 기능과 발현 기작을 규명하고자 하였다. 이러한 연구의 결과들은 체외수정, ICSI, ROSI 등의 임상치료기술의 개선에 기초자료로 활용될 수 있으리라 생각한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.497-502
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• 2002

This paper describes a design methodology of a tri-axial silicon-based farce sensor with square membrane by using micromachining technology (MEMS). The sensor has a maximum farce range of 5 N and a minimum force range of 0.1N in the three-axis directions. A simple beam theory was adopted to design the shape of the micro-force sensor. Also the optimal positions of piezoresistors were determined by the strain distribution obtained from the commercial finite element analysis program, ANSYS. The Wheatstone bridge circuits were designed to consider the sensitivity of the force sensor and its temperature compensation. Finally the process for microfabrication was designed using micromachining technology.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1988-1991
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• 2005

A micro fluid actuator driven by electromagnetic force at MEMS(Micro Electro Mechanical System) level has been designed. The operation of the actuator was simulated in three steps. First, fluid flow analysis has been performed to determine the actuator load. With the load, dynamic behavior of the actuator structure has been analysed. Finally, fluid-structure interaction analysis has been performed to predict the performance of the actuator. To avoid excessive amount of computation, axisymmetric and plane strain 2-D models were used.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.21-30
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• 2008

The purpose of this study was to investigate changes in mechanical properties of human tibialis anterior following eccentric exercise. Healthy subjects (n=12) performed 120 maximum eccentric contraction of ankle dorsiflexor. Before and 1- and 24- hour after the eccentric exercise, ankle dorsiflexion moment-angle relationships were obtained. Along with significant decrease in maximum isometric muscle strength, the shift of the optimum ankle joint angle toward the longer muscle length direction was observed, independent of the ranges of motion of the eccentric exercise. The results of this study demonstrated that eccentric exercise-induced micro muscle damage(Morgan & Allen, 1999) does rut seem to be a sole mechanism of eccentric contraction-induced muscle damage, suggesting further investigation for the better understandings of this phenomenon.

• Journal of Life Science
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• v.30 no.8
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• pp.722-730
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• 2020

As one of the most serious health risk factors, air pollution can no longer be ignored. Particulate matter (PM) is an important and harmful component of air pollution that originates from a variety of sources. Numerous recent studies have linked PM to a range of conditions including cancer, cardiovascular, respiratory, and skin disease. The eye, despite being directly exposed to air pollution, has been investigated in very few of these studies. In this review, we describe the evidence from in vitro and in vivo studies, as well as epidemiological investigations, that supports the association between exposure to PM and the development of ocular conditions such as surface and retinal disease and glaucoma. Based on the results of previous studies, we suggest that PM exposure can lead to oxidative stress, inflammation, autophagy, and, ultimately, ocular surface disease. Nevertheless, almost no studies focus on ocular surface damage from PM while some epidemiological and clinical studies report on the posterior of the eye. However, the underlying pathological mechanisms in the posterior following PM exposure have yet to be identified, and further studies are therefore warranted of the ocular surface as well as the posterior part of the eye.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.195-201
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• 2005

A laterally driven electromagnetic microactuator (LaDEM) is presented, and a micro-optical switch is designed and fabricated as a possible application. LaDEM provides parallel actuation of the microactuator to the silicon substrate surface (in-plane mode) by the Lorentz force. Poly-silicon-on-insulator (Poly-SOI) wafers and a reactive ion etching (RIE) process were used to fabricate high-aspect-ratio vertical microstructures, which allowed the equipment of a vertical micro mirror. A fabricated arch-shaped leaf spring has a thickness of $1.8{\mu}m$, width of $16{\mu}m$, and length of $800{\mu}m$. The resistance of the fabricated structure fer the optical switch was approximately 5$\Omega$. The deflection of the leaf springs increases linearly up to about 400 mA and then it demonstrates a buckling behavior around the current value. Owing to this nonlinear phenomenon, a large displacement of $60{\mu}m$ could be measured at 566 mA. The displacement-load relation and some dynamic characteristics are analyzed using the finite element simulations.

• Applied Microscopy
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• v.32 no.2
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• pp.91-105
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• 2002

Urea transport in the kidney is mediated by a family of transporter proteins that includes renal urea transporters (UT-A) and erythrocyte urea transporters (UT-B). The cDNA of five isoforms of rat UT-A, UTA1, UT-A2, UT-A3, UT-A4, and UT-A5 have been cloned. The purpose of this study was to examine the expression of UT-A (L194), which marked UT-A1, UT-A2 and UT-A4. Male Sprague-Dawley rats, weighing approximately 200 g, were divided into three group: control rats had free access to water, dehydrated rats were deprived of water for 3 d, and water loaded rats had free access to 3% sucrose water for 3 d before being killed. The kidneys were preserved by in vivo perfusion through the abdominal aorta with the 2% paraformaldehyde-lysine- periodate (PLP) or 8% paraformaldehyde solution for 10 min. The sections were processed for immunohistochemical studies using pre-embedding immunoperoxidase method and immunogold method. In the normal rat kidney, UT-A1 was expressed intensely in the cytoplasm of the inner medullary collecting duct (IMCD) cell and UT-A2 was expressed on the plasma membrane of the terminal portion of the shortloop descending thin limb (DTL) cells (type I epithelium) and of the long-loop DTL cells (type II epithelium) in the initial part of the inner medulla. Immunoreactivity for UT-A1 in the IMCD cells, was decreased in dehydrated animals whereas strongly increased in water loaded animals compared with control animals. In the short-loop DTL, immunoreactivity for UT-A2 was increased in intensity in both dehydrated and water loaded groups. However, in the long-loop DTL of the outer part of the inner medulla, immunoreactivity for UT-A2 was markedly increase in intensity in dehydrated group, but not in water loaded group. In conclusion, in the rat kidney, UT-A1 is located in the cytoplasm of IMCD cells, whereas UT-A2 is located in the plasma membrane of both the short-and long-loop DTL cells. Immunohistochemistry studies revealed that UT-A1 and UT-A2 may have a different role in urea transport and are regulated by different mechanisms.

• Journal of Life Science
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• v.33 no.3
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• pp.295-303
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• 2023

Immune and metabolic systems are important factors in maintaining homeostasis. Immune response and metabolic regulation are highly associated, so, when the normal metabolism is disturbed, the immune response changed followed the metabolic diseases occur. Likewise, obesity is highly related to immune response. Obesity, which is caused by an imbalance in energy metabolism, is associated with metabolic diseases, such as insulin resistance, type 2 diabetes, fatty liver diseases, atherosclerosis and hypertension. As known, obesity is characterized in chronic low-grade inflammation. In obesity, the microenvironment of immune cells became inflammatory by the unique activation phenotypes of immune cells such as macrophage, natural killer cell, T cell. Also, the immune cells interact each other in cellular or cytokine mechanisms, which intensify the obesity-induced inflammatory response. This phenomenon suggests the possibility of regulating the activation of immune cells as a pharmacological therapeutic strategy for obesity in addition to the common pharmacological treatment of obesity which is aimed at inhibiting enzymes such as pancreatic lipase and α-amylase or inhibiting differentiation of preadipocytes. In this review, we summarize the activation phenotypes of macrophage, natural killer cell and T cell, and their aspects in obesity. We also summarize the pharmacological substances that alleviates obesity by regulating the activation of immune cells.

• Journal of Korean Medical classics
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• v.22 no.3
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• pp.299-320
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• 2009

한중 맥진기 관련 학술 교류와 맥진기 수출을 위한 전략으로 중국의 광주중의약대학 중의사를 대상으로 맥진과 맥진기에 대한 인식을 조사하여 보고하는 바이다. 임상에서 가장 중요하게 생각하고 활용도가 높은 전통적인 병증으로 장부병증과 팔강병증으로 나타났으며, 한방 진단방법 중 가장 중요하게 생각하고 활용하는 방법으로 문진과 맥진으로서, 그 이유는 진단 효율성과 환자와의 상담으로 나타났다. 또한 임상에서 한방 진단기기의 중요한 이유로는 측정기술과 데이터의 신뢰를 들었으며, 중요하지 않다고 생각하는 이유로는 측정기술과 데이터의 신뢰성 부족과 전통적인 진단법을 보조하기엔 적합하지 못함을 들었다. 진단방법 중에서 맥진의 중요도와 활용도는 75%가 가장 높게 나타났고, 맥진법 중에서 가장 잘 활용하는 부위는 촌구맥진법으로 나타났다. 촌구 맥진시 가장 중요하게 생각하는 요소는 환자의 자세와 손목 높이와 촌관척 부위였으며, 단안(單按)과 총안(總按)의 순서는 총안(總按)후 단안(單按)이 단연 우수하였다. 임상의 중요 맥상으로는 부침(浮沈)을 들었으며, 맥상 형성 기전과 표준화 연구에 가장 적합한 연구 방법론은 위수형세론에 입각한 문헌 연구와 병증별 맥상에 대한 임상 데이터 구축으로 나타났다. 그리고 대표적인 노인 특유의 맥상은 미세약맥이었으며, 그 이유는 노화로 인한 체력저하와 기혈부족을 들었다. 그리고 맥진기와 연계하는 만성 생활습관병 병증지표 연구개발에 가장 적합하다고 판단되는 병증 체계는 장부병증이었으며, 질병은 고혈압과 동맥경화증으로 나타났다. 또한 임상에서의 활용도와 유의성이 높은 맥진기로써의 주된 기능으로는 오장육부 상태 진단을 들었으며, 맥진기의 임상적인 활용도를 높일 수 있는 현대적인 임상 분야는 심혈관 질환이 가장 높게 나타났다. 맥진기 개발에 선행되어야 할 기반연구로는 촌관척 부위 찾기의 기준 확립과 임상 변증과의 관계 확립으로 나타났으며, 제공 받고자 하는 맥상 정보구성은 환자의 맥상명과 맥상 정도와 환자의 맥상에 따른 병증명 제시로 나타났으며, 제공되는 병증 서비스로는 장부병증이 가장 높게 나타났다.