• Journal of Biosystems Engineering
• /
• 제30권1호
• /
• pp.25-31
• /
• 2005

There are more than three hundred garlic peeling facilities in Korea and most of them use pressurized air for skin peeling operation. One of the major problems of using air for the peeling operation is the occurrence of excessive bruises on the flesh of peeled garlic which causes easy microbial contamination and shortening of the shelf lift. To reduce the occurrence of bruises during the peeling operation, a new type of garlic peeling system was developed which use pressurized water. In this system, high pressure water jets were used to separate garlic bulbs and to peel the skin of garlic cloves. Six commercial systems of this type had been developed and installed at several locations in Korea. The design and performance of the latest system according to three pressure levels were described in this paper. Peeling efficiency of the system was as high as $64.7\%$ in one cycle of peeling operation by three chambers installed in series. Incorporation of a sorting system based on machine vision and re-circulation of unpeeled and partially-peeled garlic enhanced peeling efficiency by additional $30\%$, resulting in total peeling efficiency of the final products of approximately $95\%$. Peeling capacity of the system was over 400 kg per hour.

• 한국해양공학회지
• /
• 제33권3호
• /
• pp.300-311
• /
• 2019

An ROV trencher is a type of heavy-duty work class ROV equipped with high-pressure water jet tools for cutting into the sea floor and burying cables. This kind of trencher is mostly used for PLIB operations. This paper introduces the development of this kind of ROV trencher, which has a 698 kW power system, with a 250 kW hydraulic system and two 224 kW water jet systems. The project was launched in January 2014. After four years of design, manufacturing, and system integration, we carried out two sea trials near the Yeongilman port (about 20-30 m in depth) in Pohang to evaluate the system performance in November 2017 and August 2018. Through tests, we found that most of specifications were satisfied, including a maximum bury depth of 3 m, maximum bury speed of 2 km/h, and maximum forward speed of 1.54 m/s.

• 한국레이저가공학회지
• /
• 제4권2호
• /
• pp.13-19
• /
• 2001

When a high-power laser beam is irradiated on the surface of material, it is well known that a cavity, called a keyhole induced by the pressure action of the vapor plume, is generated in the molten material. This paper describes the interaction between a pulsed CO$_2$ laser beam and water. The laser-beam is used to generate and maintain a conical depression in the water surface similar to the keyhole created during laser penetration welding. Experimental results show that the depth of laser-beam penetration is limited by hydrodynamic instability. The instability of the surface cavity can be understood by the capillary instability of a hollow jet. Theoretical computation of the steady keyhole shape has been performed. modifying the model suggested by Andrews et al. (1976). The model predicts the qualitative behavior of the keyhole but significantly underestimates the average diameter.

• Journal of Korean Neurosurgical Society
• /
• 제47권5호
• /
• pp.370-376
• /
• 2010

Objective : Although unilateral transforaminal lumbar interbody fusion (TLIF) is widely used because of its benefits, it does have some technical limitations. Removal of disk material and endplate cartilage is difficult, but essential, for proper fusion in unilateral surgery, leading to debate regarding the surgery's limitations in removing the disk material on the contralateral side. Therefore, authors have conducted a randomized, comparative cadaver study in order to evaluate the efficiency of the surgery when using conventional instruments in the preparation of the disk space and when using the recently developed high-pressure water jet system, SpineJet$^{TM}$ XL. Methods : Two spine surgeons performed diskectomies and disk preparations for TLIF in 20 lumbar disks. All cadaver/surgeon/level allocations for preparation using the SpineJet$^{TM}$ XL (HydroCision Inc., Boston, MA, USA) or conventional tools were randomized. All assessments were performed by an independent spine surgeon who was unaware of the randomizations. The authors measured the areas (cm2) and calculated the proportion (%) of the disk surfaces. The duration of the disk preparation and number of instrument insertions and withdrawals required to complete the disk preparation were recorded for all procedures. Results : The proportion of the area of removed disk tissue versus that of potentially removable disk tissue, the proportion of the area of removed endplate cartilage, and the area of removed disk tissue in the contralateral posterior portion showed 74.5 ${\pm}$ 17.2%, 18.5 ${\pm}$ 12.03%, and 67.55 ${\pm}$ 16.10%, respectively, when the SpineJet$^{TM}$ XL was used, and 52.6 ${\pm}$ 16.9%, 22.8 ${\pm}$ 17.84%, and 51.64 ${\pm}$ 19.63%, respectively, when conventional instrumentations were used. The results also showed that when the SpineJet$^{TM}$ XL was used, the proportion of the area of removed disk tissue versus that of potentially removable disk tissue and the area of removed disk tissue in the contralateral posterior portion were statistically significantly high (p < 0.001, p < 0.05, respectively). Also, compared to conventional instrumentations, the duration required to complete disk space preparation was shorter, and the frequency of instrument use and the numbers of insertions/withdrawals were lower when the SpineJet$^{TM}$ XL was used. Conclusion : The present study demonstrates that hydrosurgery using the SpineJet$^{TM}$ XL unit allows for the preparation of a greater portion of disk space and that it is less traumatic and allows for more precise endplate preparation without damage to the bony endplate. Furthermore, the SpineJet$^{TM}$ XL appears to provide tangible benefits in terms of disk space preparation for graft placement, particularly when using the unilateral TLIF approach.

• 에너지공학
• /
• 제8권2호
• /
• pp.298-308
• /
• 1999

과냉각수조로 분사되는 증기의 직접접촉 응축특성을 알아보기 위하여 다섯 개의 수평 노즐에 대해 증기 질량유량과 수조 온도를 여러 가지로 변화시키면서 실험적 연구를 수행하였다. 증기응축현상을 육안관찰과 고속 비디오 카메라를 사용한 방법으로 분석한 결과, 안정된 증기제트인 경우 증기 질량속과 수조온도가 변화함에 따라 타원형 및 원추형 증기제트 형상이 나타나는 것을 관찰하였다. 증기제트 팽창비, 증기제트 길이 및 응축연전달계수를 구하였고, 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 증기제트 길이와 응축열전달계수를 증기 질량속 및 응축추진 포텐셜의 함수로 나타낸 상관식을 구하였다. 증기제트 내부와 주위 수조온도 분포를 구했으며 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 처깅, 천이처깅, 응축진동, 안정응축, 방울응축진동 및 간헐진동응축 등 여섯 가지 영역으로 구분된 응축 영역도를 작성하였다. 그 외, 수조 벽면에서의 동압을 측정하였고, 증기 질량속과 수조온도에 따라 변화하는 증기 응축모드와 동압과는 밀접한 연관성이 있음을 확인하였다.

• 청정기술
• /
• 제27권1호
• /
• pp.39-46
• /
• 2021

4 HP, 80 LPM 급 초미세기포수 발생장치를 탑재한 도로 구조물 세척차량을 이용하여 도시 내 아파트 단지 주변 차량 통행이 많은 터널 내 콘크리트 표면과 타일 벽면을 세척하였다. 초미세기포 생성은 대기 중 공기를 2 ~ 3 LPM 으로 기액혼합 자흡펌프로 가압된 공기를 임펠러 회전력을 이용하여 마이크로 크기의 미세기포(fine-bubble)를 생성한다. 생성된 기포를 다단충돌판과 회전 노즐을 통과하면서 평균 직경 크기는 164.5 nm, 6.81 × 107 particles mL-1의 초미세기포(ultrafine bubble)를 생산하였다. 생산된 초미세기포를 함유한 세척수는 압력 150 bar, 토출량 30 LPM 으로 도로 구조물 표면에 흡착된 분진을 고압세척 분사하여 제거하였다. 분석실험은 세척 전과 후로 구분하여 표면에 흡착한 분진을 ISO 8502-3의 표면 오염 측정방법을 적용하였으며, 테이프 흡착으로 분진 입자를 채취하였다. 수집된 테이프는 중량법과 소프트웨어 ImageJ를 적용하여 분진의 무게와 입자 개수에 대한 제거율을 산정하였다. 실험 결과, 타일 벽면 표면에 흡착된 분진 입자 개수는 세척 전과 후로 각각 3,063 ± 218 particles mL-1, 20 ± 5 particles mL-1, 중량은 580 ± 82 mg, 13 ± 4 mg 으로 나타났다. 콘크리트 구조물 표면에서의 입자개수는 세척 전과 후로 각각 8,105 ± 1,738 particles mL-1, 39 ± 6 particles mL-1이었으며, 중량은 1,448 ± 190 mg, 118 ± 32 mg으로 나타났다.

• Journal of Mechanical Science and Technology
• /
• 제17권1호
• /
• pp.157-167
• /
• 2003

The exciplex fluorescence technique with the TMPD (tetamethyl-Ρ-phenylene-diamine) / naphthalene dopant system was applied in a combustion-type constant-volume spray chamber. A detailed set of calibration experiments has been performed in order to quantify the TMPD fluorescence signal. It has been demonstrated that the TMPD fluorescence intensity was directly proportional to concentration, was independent of the chamber pressure, and was not sensitive to quenching by either water vapor or carbon dioxide. Using a dual heated-jet experiment, the temperature dependence of TMPD fluorescence up to 1000 K was measured. The temperature field in the spray images was determined using a simple mixing model, and an iterative solution method was used to determine the concentration and temperature field including the additional effects of the laser sheet extinction. The integrated fuel vapor concentration compared favorably with the measured amount of injected fuel when all of the liquid fuel had evaporated.

• 대한기계학회논문집B
• /
• 제24권8호
• /
• pp.1085-1096
• /
• 2000

An experimental study was performed to examine the heat and mass transfer characteristics of $LiBr-H_2O$ solution flowing over a single horizontal tube with the water vapor absorption. Effects of the flow rate and the temperature of the solution at the top of the tube, the absorber pressure and the drainage pattern were considered. The absorption rate depends highly on the absorber pressure at the low flow rate condition while on the solution inlet temperature at the high flow rate condition. Also, when the flow rate is low, the absorption performance with the sheet flow drainage appeared to be higher than that with the dripping/jet drainage. However, at the high flow rate condition, the case became reversed. The liquid film became wavy with the higher absorption rate. The waves were more probable to form with the lower flow rate and temperature of the solution, and with the higher absorber pressure.

• 대한치과의사협회지
• /
• 제54권12호
• /
• pp.1035-1044
• /
• 2016

Purpose : The purpose of this study was to compare the plaque removal effects of vacuum oral cleaner developed for the patients with limited mobility with those of manual toothbrushes and high pressure injection oral cleaner (dental water jet). Meterials and methods : Thirty human subjects were measured with Patient Hygiene Performance index (PHP index) and O'Leary index before and after the use of toothbrush, high pressure injection oral cleaner and vacuum oral cleaner. These three different oral hygiene methods were conducted with seven-day intermittence. Then the statistical analysis was carried out to define plaque removal rate of three different oral hygiene methods (${\alpha}=.05$). Results : According to the efficacy analysis of plaque removal before and after the oral cleaning using each of three methods, significant reduction in plaque after the treatment compared to the previous state when using toothbrush, high pressure injection oral cleaner, and vacuum oral cleaner was observed (P < 0.001). PHP index of tooth brushing was higher than that of the high pressure injection oral cleaner, while PHP index of vacuum oral cleaner did not show significant difference from either of the other two methods. There was no significance difference in O'Leary index among the three methods. Conclusion : Effect of plaque removal using the vacuum oral cleaner is comparable to that of manual tooth brush or high pressure injection oral cleaner, so it will be helpful for self-oral hygiene care of the patients with limited mobility.

• 대한기계학회논문집B
• /
• 제25권12호
• /
• pp.1887-1897
• /
• 2001

Korea Atomic Energy Research Institute (KAERI) launched an intermediate scale steam explosion experiment named "Test for Real Corium Interaction with water (TROI)" using reactor material to investigate whether the molten reactor material would lead to energetic steam explosion when interacted wish cold water at low pressure. The melt-water interaction experiment is performed in a pressure vessel with the multi-dimensional fuel and water pool geometry. The novel concept of cold crucible technology, where powder of the reactor material in a water-cooled cafe is heated by high frequency induction, is firstly implemented for the generation of molten fuel. In this paper, the lest facility and cold crucible technology are introduced and the results or the first series of tests were discussed. The 5 kg of molten ZrO$_2$jet was poured into the 67cm deep water pool at 30 ∼ 95 $\^{C}$. Either spontaneous steam explosions or quenching was observed. The morphology of debris and pressure wave profiles clearly indicate the differences between the two cases.