• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.3
• /
• pp.323-329
• /
• 2011

Certified reference materials (CRMs) have been used to calibrate surface profilers for reliable measurements. In this paper, we present a newly designed step height CRM which has a step height pattern with two different widths and various special patterns for checking radial magnification, distortion of optical viewing systems, etc. Especially, it could be useful for multi-probe inspection instruments in the manufacturing lines. The fabrication was done by conventional optical lithography and dry etching process with optimized conditions. To verify the step height values, a white-light scanning interferometer was used with objective lenses having magnification of $10{\times}$ and $100{\times}$. CRMs with nominal step heights of $0.5\;{\mu}m$, $1\;{\mu}m$, $3\;{\mu}m$, $5\;{\mu}m$, $7\;{\mu}m$, and $10\;{\mu}m$ were fabricated and the uniformity of these CRMs was evaluated to be less than 3 nm ($1{\sigma}$).

• Structural Engineering and Mechanics
• /
• v.13 no.5
• /
• pp.543-556
• /
• 2002

A dynamic elastic local buckling analysis is presented for a pile subjected to an axial impact load. The pile is assumed to be geometrically perfect. The interactions between the pile and the surrounding soil are taken into account. The interactions include the normal pressure and skin friction on the surface of the pile due to the resistance of the soil. The analysis also includes the influence of the propagation of stress waves through the length of the pile to the distance at which buckling is initiated and the mass of the pile. A perturbation technique is used to determine the critical buckling length and the associated critical time. As a special case, the explicit expression for the buckling length of a pile is obtained without considering soil resistance and compared with the one obtained for a column by means of an alternative method. Numerical results obtained show good agreement with the experimental results. The effects of the normal pressure and the skin friction due to the surrounding soil, self-weight, stiffness and geometric dimension of the cross section on the critical buckling length are discussed. The sudden change of buckling modes is further considered to show the 'snap-through' phenomenon occurring as a result of stress wave propagation.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.79-80
• /
• 2023

Reinforced concrete structures require large amounts of concrete and rebar in the construction stage. Rebar is a major resource for reinforced concrete structures, and generates more CO₂ per unit weight than other materials. To solve this problem, it was confirmed that the cutting waste can be close to zero when the special length of the rebar is calculated in the drawing created after structural design. However, a system for automatically calculating the length of reinforcing bars to efficiently calculate the total amount of reinforcing bars has not been established. Therefore, the objective of this study is a basic study of automatic rebar length estimate algorithm of bearing wall by using BIM-based shape codes built in Revit. The bearing wall rebar can be automatically derived using the developed model. Furthermore, through applying the developed model to the construction field, it will greatly contribute to reducing greenhouse gas emissions by reducing rebar cutting waste.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.29 no.1
• /
• pp.15-20
• /
• 2009

The results of crack evaluation by conventional UT(Ultrasonic Test)is highly depend on the inspector's experience or knowledge of ultrasound. Phased array UT system and its application methods for small crack length evaluation will be a good alternative method which overcome present UT weakness. This study was aimed at checking the accuracy of crack length evaluation method by electronic scanning and discuss about characteristics of electronic scanning for crack length evaluation. Especially ultrasonic phased array with electronic scan technique was used in carrying out both sizing and detect ability of crack as its length changes. The response of ultrasonic phased array was analyzed to obtain the special method of determining crack length without moving the transducer and detect-ability of crack minimal length and depth from the material. A method of crack length determining by electronic scanning for the small crack is very real method which has it's accuracy and verify the effectiveness of method compared to a conventional crack length determination.

• The Journal of the Korea Contents Association
• /
• v.21 no.5
• /
• pp.268-275
• /
• 2021

In special education, the operation of curriculum for students subject to special education is a role given to special teachers and integrated class teachers, and there are prior studies that many teachers experience difficulties in operating the curriculum. In this study, it was intended to find out the direction of special education courses and appropriate support measures for the operation of special education courses by exploring the experiences of special teachers and integrated class teachers, difficulties and suggestions in operating the curriculum. Participants in this study were special and integrated teachers with more than 15 years of experience, and all interviews were conducted in one-on-one in-depth interviews. After all the interviews have been prepared in full-length versions, the analysis has resulted in six major subjects and twelve subtopics; each teacher has different curriculum operations, difficulties in applying the curriculum, insufficient support systems, professional qualifications, and daily concerns of teachers in integrated classes. In the discussion, the direction of operation of special education courses for students and appropriate support measures for the operation of curriculum were discussed, and the limitations of research were presented and proposed.

• Korean Journal of Applied Biomechanics
• /
• v.28 no.2
• /
• pp.135-141
• /
• 2018

Objective: The purpose of this study was to investigate the effect of functional ankle instability (FAI) and surgical treatment (ST) on postural stability and leg stiffness during vertical-drop landing. Method: A total of 21 men participated in this study (normal [NOR]: 7, FAI: 7, ST: 7). We estimated dimensionless leg stiffness as the ratio of the peak vertical ground reaction force and the change in stance-phase leg length. Leg length was calculated as the distance from the center of the pelvis to the center of pressure under the foot. Furthermore, the analyzed variables included the loading rate and the dynamic postural stability index (DPSI; medial-lateral [ML], anterior-posterior [AP], and vertical [V]) in the initial contact phase. Results: The dimensionless leg stiffness in the FAI group was higher than that of the NOR group and the ST group (p = .018). This result may be due to a smaller change in stance-phase leg length (p = .001). DPSI (ML, AP, and V) and loading rate did not show differences according to the types of ankle instability during drop landing (p > .05). Conclusion: This study suggested that the dimensionless leg stiffness was within the normal range in the ST group, whereas it was increased by the stiffness of the legs rather than the peak vertical force during vertical-drop landing in the FAI group. Identifying these potential differences may enable clinicians to assess ankle instability and design rehabilitation protocols specific for the impairment.

• Journal of Aquaculture
• /
• v.12 no.4
• /
• pp.255-266
• /
• 1999

The early development, growth, and morphological changes of Tiger puffer Takifugu rubripes are described on the basis of a seres of a series of reared specimens. Detailed o수 the early developmental stages are illusrtated withe special reference to morphological transformation. Egg and sperm of puffer fish Takifugu rubripes were obtained from mature adults under natural conditions, ferilized artificially and incubated in the laboratory. The incubation period of fertilizd eggs was 160 to 180 hours at a temperature of $15.1~ 18.0^{\circ}C$. Larvae were fed successively with rotifer, Artemia nauplii and artificial food for 90 days. The mean total length of newly-hatched larvae was about 2.8mm. Mouth opening occurred on the 1- day yolk-sac larvae and initial feeding was observed on th 4-5 days after hatching . The morphological transitions from the larvae to juvenile and juvenile and juvenile to young stages occurred when fish reached about 10mm in total length(about 30 days after hatching) and about 32mm in total length(about 60days after hatching) , respectively. The coefficient of variation in total length distribution increased with growth. Following the appearance of its peak at the size of about 18mm in total length, the coefficient value declined. Many changes in proportion of the body parts to total length were observed at about 9~10mm and 30~33mm in total length, corresponding to the transformations from larvae to juvenile and from juvenile to young, respectively. Also one big morphological change was observed at about 18mm in total length that divide the juvenile stage into two sub-stages.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2020.08a
• /
• pp.57-57
• /
• 2020

다래(Actinidia arguta (Siebold & Zucc.) Planch. ex Miq.)의 재배에서 현재 많이 이용되고 있는 평덕형은 기존의 T덕형에 비해 가지의 배치가 자유롭고 수확량이 많은 장점이 있다. 평덕형을 활용한 다래 재배에서 결과모지의 전정 길이에 대한 연구는 미흡한 실정이며, T덕형과 마찬가지로 15cm 길이의 단초전정이 권장되어 있다. 본 연구에서는 평덕형에서 품종별로 수확량을 증대하면서 과실 품질을 향상시킬 수 있는 적정한 결과모지 길이를 결정하고자 하였다. 이를 위해 과실 특성이 다른 '오텀센스'와 '대보' 품종을 이용하여 결과모지가 30, 50, 100, 150 및 200cm 길이가 되도록 전정하고, 수확기인 9월에 수확량 및 열매 특성을 조사하였다. 평덕형의 경우 품종과 결과모지 전정길이에 따라서 가지수, 결과지의 수, 총 착과 수, 열매무게 및 총 수확량에서 유의적인 차이를 보였다. 두 품종 모두 150cm로 결과모지를 전정하였을 때 결과모지당 착과 수가 각각 129±71개 및 27±8개로 가장 좋았으며, 총 수확량 역시 각각 1,697.0±990.4g 및 849.0±243.2g으로 가장 좋았다. '오텀센스'와 '대보' 품종은 평덕재배시 결과모지를 150cm로 전정하는 것이 생산량 증대 및 품질 특성이 우수한 것으로 나타났다.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2020.08a
• /
• pp.58-58
• /
• 2020

다양한 품종이 개발되어 재배되고 있는 다래(Actinidia arguta (Siebold & Zucc.) Planch. ex Miq.)의 재배유형이 T덕형과 평덕형으로 나누어지고, 덕 형태 및 품종에 따라 다래의 생육 양상에 차이가 있음에도 불구하고 결과모지 길이를 15cm 길이의 단일한 형태로 전정해 왔다. 본 연구에서는 T덕형을 활용한 다래 재배에서 품종별로 수확량을 증대하면서 과실 품질을 향상시킬 수 있는 적정한 결과모지 길이를 결정하고자 하였다. 이를 위해 국립산림과학원에서 개발한 '새한', '대성' '칠보' 및 '오텀센스' 등 4품종을 대상으로 하여 결과모지 길이가 15, 30 및 50cm가 되도록 전정하였다. 동일한 방법으로 재배한 후 수확기인 9월에 수확량 및 열매 특성을 조사하였다. 그 결과 품종과 가지수, 결과지의 수와 미결실지 수, 열매 무게, 총 수확량 에서 유의한 차이가 있었고, 전정 길이에 따라서는 총 착과 수, 열매 무게 및 총 수확량에서 차이가 있었다. 모든 품종에서 결과모지 길이가 길어질수록 총 수확량은 증가하였으며, 총 수확량은 품종에 따라 2~7배까지 증가하는 경향을 보였다. 결과모지 전정은 '새한', '대성' 및 '오텀센스'는 50cm 전정에서 칠보는 30cm 전정에서 생산량 및 품질특성이 우수하였다.

• Proceedings of the KIEE Conference
• /
• 2007.04c
• /
• pp.159-161
• /
• 2007

$CO_2$ laser sees that is most suitable to get this effect through minimum formation damage and advantage that is root enemy of effect that happen in minimum cellular tissue depth of 0.1mm is stable living body organization or internal organs institution. Formation damage by ten can be related in formation's kind or energy density, length of evaporation time. If shorten evaporation time, surroundings cellular thermal damage 200 - because happen within 400ums laser beam in rain focus sacred ground surroundings cellular tissue without vitiation me by evaporation Poe of very small floor as is clean steam can. Application is possible to vulva cuticle cousins by a paternal aunt quantity, uterine cancer, cuticle tumor by laser system that $CO_2$ laser gets into standard in obstetrics and gynecology application. Because effect that super pulse output is ten enemies of laser if uniformity one pulse durations are short almost is decreased, most of all pulse module special quality of pulse style $CO_2$ laser for obstetrics and gynecology mode stabilization by weight very, in this research to get into short pulse duration and higher frequency density, do switching by high frequency in DC-DC Converter output DC's ripple high frequency to be changed, high frequency done current ripple amount of condenser for output filter greatly reduce can. Ripple of output approximately to Zero realization applying possible inductor realization through a special quality experiment do.