• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.435-440
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• 2000

In this study, we aims to develop the machining technology for the ultra precision surface and profile accuracy. For this purpose, we construct the electrolytic in process grinding system (ELID grinding) and apply to the cylindrical and internal grinding. Through the various machining experiments such as SCM steel., ceramics, tungsten carbide etc., we have obtained nanometer surface roughness. And we have applied this mirror grinding technique to hydraulic manual valve and mold core of mini disk optical pick-up base. For the development of fine mechanical part machining technology, e have made multi fiber optical connector using fine grinding technology. And constructed micro drilling system with process monitoring system which is possible to drill 50${\mu}{\textrm}{m}$ diameter hole.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.1041-1044
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• 1996

The plastic-film-covered hill planter is a new-type seeding machine, including tow types which are mounted by 11kw and 40 kw tractors. It is made up of fertilizing , plastic-film covering perforating film and hole seeding, soil sealing apparatus, and can work at 5-7kw/h. The plastic-film covering and seeding of cotton, corn and soybean can all use this machine. The plastic-film-covered hill planter is mainly composed of plastic film covering unit, drum-type hill-drop unit and furrow coverer, some other types are also equipped with fertilizer drill unit. It can do combined work of covering plastic film , sowing , plastic film perforating , soil covering at one time, and it is suitable to the covering plastic film as well as planting of the grandulated crops, such as cotton , corn, soybean and so on.

• 화약ㆍ발파
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• 제17권1호
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• pp.19-26
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• 1999

Rock fragmentation with plasma blasting technique has advantageous properties in contrast to the conventional blasting method in controlling of flying rocks and ground vibrations when residents are complaining or surrounding structures stay in protection from blasting operations. The experiences show in urban construction works that the plasma blasting is the most possible method to prevent damages and minimize adverse environmental impacts. The fragmentation energy level is evaluated by numerical simulation using PFC for various drill hole pattern and tested accordingly to get the feasibility. The energy output of plasma blasting system has been improved to a level of 1 MJ, which can break a $2-3m^3$ granite boulder or 1.5m height bench face. Measurements are carried out to get the ground vibration level and propagation equation. So that the control of the blasting operations can be performed more precisely and safely.

• 한국정밀공학회지
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• 제18권10호
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• pp.200-207
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• 2001

Burrs farmed in drilling are classified into three types, no burr, burrs with cap, teared burr. To control burr size in drilling, the second type burrs with cap are to be formed because it is small and uniform. It is necessary to understand the mechanism of cap formation to derive the burr formation into second type burr with cap. In several materials. second type burrs are formed in drilling by changing cutting conditions. It is observed that cap is formed as a result of the plastic deformation along the outside of exit hope. According to the tension behavior of the material in concentrated region between hole and drill outside edge, the geometry of burr with cap is determined. Simplified 2D FEM analysis shows good prediction for burr formation.

• 한국정밀공학회지
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• 제18권2호
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• pp.79-83
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• 2001

A verification of multi-spindles drilling NC data is presented. The drilling of multi-spindles can offer productivity over three times as fast as that of single spindle. The most important things in machining tube sheet are precision of hole position and machining time. The drilling of multi-spindles has difficulties in controlling many motors to drive spindles and assign a correspondent number to each spindles. Multi-spindles drilling has different codes from CNC milling ; many subroutines, assignment of spindle, and so on. The conventional method, which inspects the NC code of the drilling, is to drill holes on a thin plate or tube sheet previously. The method results in low productivity because it consumed long machining time and welding for correction. This paper describes details of multi-spindles NC code and operation of multi-spindles drilling machine. A verification software of the multi-spindles drilling NC code is developed on the details.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.629-640
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• 2008

South anchorage(AN1, Myodo side) of supension bridge between Myodo and Gwangyang is designed as rock anchorage with 36m anchor length using the resistance of rock mass in Myodo. Checking the overall stability of the anchorage, we considered rock joints, bedding planes, fault zones and condition of rock structure in situ by analysis results for photo-lineaments, aerial photograph interpretation and drill-hole logs are considered. This anchorage consists of an access shaft, adit, and the upper and lower concrete bearing plate to introduce pre-stressing force into rock mass.

• Journal of Korean Neurosurgical Society
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• 제52권2호
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• pp.133-137
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• 2012

Objective : Twist-drill craniostomy (TDC) with closed-system drainage and burr-hole drainage (BHD) with a closed system are effective treatment options for chronic subdural hematoma (CSDH). The aim of this study was to analyze clinical data and surgical results from symptomatic CSDH patients who underwent TDC with closed-system drainage at the pre-coronal point (PCP). Methods : We analyzed data for 134 symptomatic CSDH patients who underwent TDC at the PCP with closed-system drainage. We defined the PCP for TDC to be 1 cm anterior to the coronal suture at the level of superior temporal line. TDC at the PCP with closed-system drainage was selected in patients with CSDH that extended beyond the coronal suture, confirmed by preoperative CT scans. Medical records, radiological findings, and clinical performance were reviewed retrospectively. Results : Of the 134 CSDH patients, 114 (85.1%) showed improved clinical performance and imaging findings after surgery. Catheter failures were seen in two cases (1.4%); the catheters were inserted in the epidural space. Recurrent cases were seen in eight patients (5.6%), and they were improved with a second BHD with a closed-system operation. Conclusion : TDC at the PCP with closed-system drainage is safe and effective for patients with symptomatic CSDH whose hematomas extend beyond the coronal suture.

• Journal of Korean Neurosurgical Society
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• 제37권2호
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• pp.105-111
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• 2005

Objective: Tremor, either essential tremor or Parkinsonian tremor, has been effectively and safely treated by lesioning the ventral intermediate(Vim) nucleus of the thalamus with or without mircroelectrode recording. The authors evaluate the treatment outcome of sixteen tremor patients who had been treated with thalamotomy without microelectrode. Methods: Between September, 2001, and December, 2003, sixteen tremor patients were treated with thalamotomy without microelectrode recording. Twelve patients suffered from Parkinsonian tremor and four patients were essential tremor patients. The male to female ratio was 1.6 to 1 with median age of 59.6 years (range; 39-74 years). Under local anesthesia, a 3mm hole was made using a hand-held twist drill, and the dura mater was penetrated with a 1.2mm sharp drill beat. Radiofrequency(RF) electrode was placed in the Vim nucleus of thalamus. With intraoperative macrostimulation, RF lesion was made. Postoperative CT scan and/or MR imaging was performed to confirm the localization of the target lesioned. Preoperative and postoperative tremor was evaluated with simple tremor severity scale and the development of complications related with the procedure was closely reviewed at the immediate postoperative period and the last follow-up. Results: It produces immediate relief in up to 98.4% of the patients. There were no development of complications related with procedure, all patients discharged one or two days after surgery. Conclusion: Vim thalamotomy without microelectrode recording is a safe and effective procedure to control the tremor with minimal morbidity. Intraoperative macroelectrode stimulation safely localizes the Vim nucleus target of the thalamus for the treatment of patients with tremor.

• 한국지반신소재학회논문집
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• 제18권4호
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• pp.115-127
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• 2019

본 연구의 대상 공법인 저유동성 그라우팅 주입공법은 모르타르를 주입재로 하여 비배출 치환원리에 의해 지중에 압입하는 공법으로서 지반의 밀도 증대효과를 기대할 수 있고 저소음, 저공해, 내구성 확보와 함께 경우에 따라서는 높은 주입 고결체의 강도를 이용한 기초파일로 사용할 수도 있다. 저유동성 주입공법으로 지반의 동적 특성이 향상됨을 확인하기 위하여 현장에서 시험시공을 실시하고 물리시험을 수행하였으며 코어에 대한 실내시험을 통해 지중에 형성된 개량체 품질을 확인하고 코어회수율 분석을 수행하였다. 밀도검층은 감마선의 컴프턴 산란을 이용하여 지층의 체적 밀도를 산정하였고, 음파검층은 시추공 내에서 음파발생 및 수신장치로 구성된 검층기를 이용하여 시추공 주변의 지반에 대해서 시험을 실시하였다. 그라우팅 전,후 물성변화(밀도검층, 음파검층)를 측정한 결과, 기본적으로 두 물성 모두 그라우트제 주입 후 물성이 증가하여 측정되었다. 다만, 그라우팅 후 속도 증가보다 밀도 증가의 변화 폭이 컸으며, 지반 밀도 측정 방법이 주입재의 충진 효과를 측정하는데 효과적이다. 재령 28일 후 채취한 시료로부터 강도 및 코어회수율을 측정하였으며, 시험결과 개량체의 확산 및 강도시험 결과가 설계기준을 만족시켜 내진성능보강을 만족한 것으로 확인하였다.

• 지질공학
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• 제21권1호
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• pp.15-24
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• 2011

기존의 지표탐사 자료가 존재하는 화강암 지역의 파쇄대 및 절리 분포를 파악하기 위해 30m 떨어져 있는 두 개의 시추공에 대한 코어자료 분석 및 물리검층을 실시하였다. 시추 코어 자료를 이용하여 암상을 구분하였고 RMR(암반분류)과 RQD(암질지수)에 의한 암반 상태를 확인하였으며, 기반암에 해당되는 연암과 경암 부분에 대한 파쇄대의 절리 및 분포 상태를 물리검층과 시추공 탄성파 토모그래피를 통해 확인하였다. 이미 탄성파 굴절법탐사에서 해석된 기반암까지의 깊이를 공대공 탄성파 토모그래피를 통해 확인하였고 암반의 동적인 성질을 파악하기 위해 완전파형 음파검층과 감마-감마검층으로 동탄성계수를 계산하여 P파 속도와의 상관관계를 알아보았다. 특히 시추공 BH-2의 경암 부근에서 그 상관성이 넓게 분산되는 현상은 절리 및 파쇄대가 BH-1 지역에 비해 많이 발달한 효과로 보인다. 이 양상은 초음파 주사형 텔레뷰어 및 광학적 영상기법 텔레뷰어와 같은 이미지 검층 자료에서도 충분히 관찰되었다.