• 한국지열·수열에너지학회논문집
• /
• 제17권1호
• /
• pp.14-22
• /
• 2021

Drilling equipment is an essential part used in various fields such as construction, mining, etc., and it has drawn increasing attention in recent years. The drilling method is generally divided into three types. There are a top hammer method that strikes on the ground, a DTH (Down-The-Hole) method that directly strikes a bit in an underground area, and a rotary method that drills by using rotational force. Among them, the DTH method is most commonly used because it enables efficient drilling compared to other drilling methods. In the conventional DTH hammer, the valve between the piston and the bit is opened and closed using a face to face method. In order to improve the power of the DTH hammer, a DTH hammer with foot valve which is capable of instantaneous opening and closing is used in the drilling field. In this study, we designed a lab-scale DTH hammer with the foot valve, and manufactured an evaluation device for the experiment of the DTH hammer. In addition, we analyzed the performance of the DTH hammer adopted with foot valve according to the pressure range of 3-10 bar. As a result, the internal pressure distribution in the DTH hammer was experimentally analyzed, and then, the movement of the piston according to the pressure was predicted. We believe that this study provides the useful results to explain the performance characteristics of the DTH hammer with the foot valve.

• 대한통합의학회지
• /
• 제8권4호
• /
• pp.241-251
• /
• 2020

Purpose : This study examined the effect of locomotive syndrome on stress index and lifestyle patterns among elderly Koreans aged 65 years and older, and analyzed its correlation with stress index and lifestyle patterns. The purpose of this study was to provide basic data for the management and prevention of locomotive syndrome in the elderly. Methods : Using the "25-Question Geriatric Locomotive Function Scale (GLFS-25)", the study evaluated locomotive syndrome in 123 elderly Koreans aged 65 years and older. Of them, 85 patients were assigned to the locomotive syndrome group and 38 patients were assigned to the normal group. The questionnaire measured and investigated the participants' stress index and lifestyle patterns. Statistical analysis was performed using SPSS 22.0 ver. Results : Results showed the locomotive syndrome group displayed a higher stress index than the normal group, with a statistically significant difference between the two groups. The group also scored lower in the lifestyle pattern survey than the normal group did, with a statistically significant difference in high-intensity work performance ratio and average daily performance time between them. The GLFS-25 score showed a significant positive correlation with the stress index and sitting and lying down time, and a significant negative correlation with medium-intensity working time, walking, and cycling time. Conclusion : In conclusion, Locomotive syndrome in elderly Koreans is closely related to stress and lifestyle patterns, especially high-intensity work. We recommend active prevention and management of locomotive syndrome and further research into the effects of various lifestyle factors on the illness.

• Journal of the Korean Wood Science and Technology
• /
• 제51권1호
• /
• pp.58-66
• /
• 2023

In light-frame timber construction, the shear wall is one of the most important components that provide resistance to lateral loads such as earthquakes or winds. According to KDS (Korea Design Standard) 42 50 10, shear walls are to be constructed using wood-based structural sheathing, with studs connected by 8d nails spaced 150 mm along the edge and 300 mm in the field. Even though small-scale residential timber building can be designed to exhibit seismic resistance using light-frame timber shear walls in accordance with KDS 42 50 10, only the abovementioned standard type of timber shear wall is available. Therefore, more types of timber shear walls composed of various materials should be tested to measure their seismic resistance, and the results should be incorporated into the future revision of KDS 42 50 10. In this study, the seismic resistance of shear walls composed of structural timber studs and wood-based structural sheathing with reinforced nailing is tested to evaluate the effects of the reinforcement. For the nailing reinforcement, shear wall specimens are constructed by applying nail spacings of 75-150 mm and 50-100 mm. For the shear wall specimens with one sheathing and reinforced nailing, the shear strengths are 1.7-2.0 times higher than that of the standard shear wall (nail spacing of 150-300 mm). The shear strength of the shear walls with sheathing on both sides is 2.0-2.7 times higher than that of the standard shear wall.

• 예술인문사회 융합 멀티미디어 논문지
• /
• 제6권2호
• /
• pp.35-44
• /
• 2016

최근 마이스산업이 신성장동력산업으로 떠오르고 있다. 국내의 대부분 MICE행사는 소규모/저비용으로 진행되고 있다. 행사주최자 입장에서는 반복, 소모적으로 발생하는 브로슈어, 홍보물제작 등의 인쇄물 비용의 절감과 행사진행에 필요한 단순 안내진행요원들의 경비 절감을 원하고 있다. 기존 모바일웹은 행사 참가자가 필요한 정보를 바로 얻지 못하고 스스로 정보를 찾고 검색해야 되는 단점이 있다. 따라서 행사기간에 단기적으로 사용할 수 있는 저비용, 고효율의 행사정보 제공 솔루션의 개발이 필요하다. 본 연구에서는 비콘 기술을 이용한 전시/컨벤션 행사용 통합관리시스템을 구현하였다. 비콘 기술을 적용하여 행사현장 안내시스템을 통한 행사지원 관리의 효율성을 제공하고, 콘텐츠관리시스템(CMS)을 이용한 디지털브로슈어 관리기능을 통한 정보검색 용이성과 비용절감 효과를 높일 수 있다. 소규모 전시/컨벤션 행사에 주최 측의 직접 홈페이지 구축과 현장관리시스템 운영을 통해 효율적인 행사관리를 할 수 있다.

• 천문학회보
• /
• 제46권2호
• /
• pp.37.2-37.2
• /
• 2021

Turbulence produces the density and velocity fluctuations in molecular clouds, and dense regions within the density fluctuation are the birthplace of stars. Also, turbulence can produce non-thermal pressure against gravity. Thus, turbulence plays a crucial roles in controlling star formation. However, despite many years of study, the detailed relation between turbulence and star formation remain poorly understood. As part of the Taeduk Radio Astronomy Observatory (TRAO) Key Science Program (KSP), "mapping Turbulent properties In star-forming MolEcular clouds down to the Sonic scale (TIMES; PI: Jeong-Eun Lee)", we mapped two star-forming molecular clouds, the Orion A and the ρ Ophiuchus molecular clouds, in six molecular lines (¹³CO 1-0/C¹⁸O 1-0, HCN 1-0/HCO⁺ 1-0, and CS 2-1/N₂H⁺ 1-0) using the TRAO 14-m telescope. We applied the Principal Component Analysis (PCA) to the observed data in two different ways. The first method is analyzing the variation of line intensities in velocity space to evaluate the velocity power spectrum of underlying turbulence. We investigated the relation between the star formation activities and properties of turbulence. The other method is analyzing the variation of the integrated intensities between the molecular lines to find the characteristic correlation between them. We found that the HCN, HCO⁺, and CS lines well correlate with each other in the integral shaped filament in the Orion A cloud, while the HCO⁺ line is anti-correlate with the HCN and CS lines in L1688 of the Ophiuchus cloud.

• 천문학회보
• /
• 제44권2호
• /
• pp.68.1-68.1
• /
• 2019

Turbulence plays a crucial role in controlling star formation as it produces density fluctuation as well as non-thermal pressure against gravity. Therefore, turbulence controls the mode and tempo of star formation. However, despite a plenty of previous studies, the properties of turbulence remain poorly understood. As part of the Taeduk Radio Astronomy Observatory (TRAO) Key Science Program (KSP), "mapping Turbulent properties In star-forming MolEcular clouds down to the Sonic scale (TIMES; PI: Jeong-Eun Lee)", we mapped the Orion A and the Ophiuchus clouds, in three sets of lines (13CO 1-0/C18O 1-0, HCN 1-0/HCO+ 1-0, and CS 2-1/N2H+ 1-0) with a high-velocity resolution (~0.1 km/s) using the TRAO 14-m telescope. The mean Trms for the observed maps are less than 0.25 K, and all these maps show uniform Trms values throughout the observed area. These homogeneous and high signal-to-noise ratio data provide the best chance to probe the nature of turbulence in two different star-forming clouds, the Orion A and Ophiuchus clouds. We present comparisons between the line intensities of different molecular tracers as well as the results of a Principal Component Analysis (PCA).

• 대한한방내과학회지
• /
• 제44권3호
• /
• pp.544-554
• /
• 2023

Background: Postural hypotension refers to a drop in systolic blood pressure of 20 mmHg or diastolic blood pressure of 10 mmHg or more within three minutes after standing up from lying down. Symptoms of postural hypotension not only include dizziness and blurred vision but also fatigue, cognitive decline, leg weakness, headache, and, in severe cases, fainting. Postural hypotension is a phenomenon that occurs in about 6% of the total population, and in Korea, the number of patients with postural hypotension is continuously increasing. Both pharmacological and non-drug therapies, which are treatment methods for this disease, do not show a satisfactory symptom improvement effect. Case summary: A 65-year-old male patient who visited the hospital complaining of dizziness and paresthesia due to postural hypotension was treated with acupuncture, moxibustion, and herbal medicine. For symptom evaluation, the numeric rating scale (NRS) of each symptom was used, and blood pressure change according to posture was measured. After treatment, the NRSs of dizziness and dysesthesia were decreased, and blood pressure changes according to posture was improved. Conclusion: This case report suggests that Korean medicine treatment, including acupuncture, electro-acupuncture, moxibustion, and herbal medicine, can be an effective treatment for dizziness with postural hypotension.

• 한국의학물리학회지:의학물리
• /
• 제33권4호
• /
• pp.114-120
• /
• 2022

Purpose: Particle beam therapy is advantageous over photon therapy. However, adequately delivering therapeutic doses to tumors near critical organs is difficult. Nanoparticle-aided radiation therapy can be used to alleviate this problem, wherein nanoparticles can passively accumulate at higher concentrations in the tumor tissue compared to the surrounding normal tissue. In this study, we investigate the dose enhancement effect due to gold nanoparticle (GNP) when Carbon-12, He-4, and proton beams are irradiated on GNP. Methods: First, monoenergetic Carbon-12 and He-4 ion beams of energy of 283.33 MeV/u and 150 MeV/u, respectively, and a proton beam of energy of 150 MeV were irradiated on a water phantom of dimensions 30 cm×30 cm×30 cm. Subsequently, the secondary-particle information generated near the Bragg peak was recorded in a phase-space (phsp) file. Second, the obtained phsp file was scaled down to a nanometer scale to irradiate GNP of diameter 50 nm located at the center of a 4 ㎛×4 ㎛×4 ㎛ water phantom. The dose enhancement ratio (DER) was calculated in intervals of 1 nm from the GNP surface. Results: The DER of GNP computed at 1 nm from the GNP surface was 4.70, 4.86, and 4.89 for Carbon-12, He-4, and proton beams, respectively; the DER decreased rapidly with increasing distance from the GNP surface. Conclusions: The results indicated that GNP can be used as radiosensitizers in particle beam therapy. Furthermore, the dose enhancement effect of the GNP absorbed by tumor cells can aid in delivering higher therapeutic doses.

• 대한한방내과학회지
• /
• 제45권1호
• /
• pp.111-118
• /
• 2024

목적: 본 연구는 임상에서 종종 마주치는 만성적이고 낫지 않는 항문거근증후군 환자의 한의학적 치료 유용성을 공유하고자 한다. 방법: 14년 전에 치질수술 후에 발생한 항문통증이 개선되지 않고 지속되어 고통스러웠던 47세 남자 환자의 병력과 한의학적 치료 후의 임상적 개선과정을 자세히 제시하였다. 결과: 환자는 평소 건강하였는데, 치질수술 후에 대변을 보면 시작되는 항문통이 발생하였으며, 경우에 따라서는 오전 내내 불편함이 지속되었다. 14년 동안 종종 줄어들기도 하였지만 점진적으로 심해지는 경과를 보였고, 특히 1년 전부터는 더욱 심해졌으나 다양한 치료에도 호전이 없었다. 외국에 거주하는 이유로 한국에 방문하는 기회에 본원에서 한의학적 변증 하에 한약치료 및 약침을 포함하는 침치료와 뜸 치료 후 빠르게 호전되었다. 8주 정도의 치료 후에 NRS 2로 개선되어 만족한 상태로 출국하였다. 결론: 본 증례는 특별한 치료법이 부재하는 만성적이거나 혹은 난치성 항문거근증후군에 대하여 한의학적 치료법이 하나의 훌륭한 치료법일 수 있음을 보여주는 임상 예로서 의미가 있다고 하겠다.

• Wind and Structures
• /
• 제38권2호
• /
• pp.129-146
• /
• 2024

Aiming at the problem of non-stationary wind field simulation of downbursts, a non-stationary down-burst generation system was designed by adding a nozzle and program control valve to the inlet of the original wall jet model. The computational fluid dynamics (CFD) method was used to simulate the downburst. Firstly, the two-dimensional (2D) model was used to study the outflow situation, and the database of working conditions was formed. Then the combined superposition of working conditions was carried out to simulate the full-scale measured downburst. The three-dimensional (3D) large eddy simulation (LES) was used for further verification based on this superposition condition. Finally, the wind tunnel test is used to further verify. The results show that after the valve is opened, the wind ve-locity at low altitude increases rapidly, then stays stable, and the wind velocity at each point fluctuates. The velocity of the 2D model matches the wind velocity trend of the measured downburst well. The 3D model matches the measured downburst flow in terms of wind velocity and pulsation characteris-tics. The time-varying mean wind velocity of the wind tunnel test is in better agreement with the meas-ured time-varying mean wind velocity of the downburst. The power spectrum of fluctuating wind ve-locity at different vertical heights for the test condition also agrees well with the von Karman spectrum, and conforms to the "-5/3" law. The vertical profile of the maximum time-varying average wind veloci-ty obtained from the test shows the basic characteristics of the typical wind profile of the downburst. The effectiveness of the downburst generation system is verified.