• 수산해양기술연구
• /
• 제50권3호
• /
• pp.274-283
• /
• 2014

Swelling of the heat-treated netting for gillnet was estimated through the netting height in square acrylic tank. Experimental Nylon netting and PBSAT netting were heat-treated by using the high-degree vacuum method in hot water after net making. Heat-treatment temperatures were conducted with Nylon netting $105^{\circ}C$ and PBSAT netting $62^{\circ}C$, $65^{\circ}C$, $66^{\circ}C$, $67^{\circ}C$. The swelling measurement method of a netting using the square tank was capable of the reduction measurement errors comparing with measurement methods of a mesh inner angle and the shortening rate of a mesh size. In addition, this method was available to comparison evaluation for each netting more easily. Wet type heat-treatment apparatus with high-degree vacuum was shown higher $7{\sim}8^{\circ}C$ inner side temperature than a setting temperature. The tensile strength and elongation of Nylon netting and PBSAT netting were shown higher wet condition than dry condition. The tensile strengths of PBSAT monofilaments in dry and wet condition were sharply decreased at heat-treatment temp. $75^{\circ}C$ than heat-treatment temp. $74^{\circ}C$.

• 한국항공우주학회지
• /
• 제37권12호
• /
• pp.1201-1208
• /
• 2009

액체로켓 연소기의 재생냉각 챔버의 제작에 사용되는 구리합금의 성형성을 돔 장출 시험과 인장시험을 수행하여 평가하였다. 성형성 평가에 사용된 시편은 열처리 유무와 재료의 방향성을 고려하여 제작하여 고온 열처리와 재료의 방향성이 성형성에 미치는 영향을 평가하였다. 시험 결과 열처리 후 구리합금 재료의 성형한계 값은 열처리 전 시편의 성형한계 값에 비하여 증가하였으나, 시편의 제작 방향에 따른 성형성의 차이는 열처리 영향에 비하여 작게 나타났다. 그리고 성형성 평가 시험방법에 따라 성형한계 값이 다르게 나타났다. 이러한 결과 들로부터 연소기 재생냉각 챔버의 내측구조물에서 실린더 형상의 구조물을 벌징 공정으로 네킹이나 파손 없이 노즐 형상으로 성공적으로 성형하기 위해서는 벌징 전 재료에 대한 고온열처리가 매우 중요함을 확인하였다. 또한 시험방법이 성형성 평가에 크게 영향을 미치는 것을 확인하였다. 본 연구를 통하여 얻은 구리합금의 성형한계도는 이 재료를 사용하여 제작하는 연소기 재생냉각 챔버 노즐의 구조설계를 위한 데이터로 활용할 예정이다.

• International Journal of Ocean System Engineering
• /
• 제2권4호
• /
• pp.209-213
• /
• 2012

Recently, the fuel using in the diesel engines of marine ships has been changed to a low quality of heavy oil because of the steady increase in the price of oil. Therefore, the wear and corrosion in all parts of the engine such as the cylinder liner, piston crown, and spindle and seat ring of exhaust valves has correspondingly increased. The repair welding of a piston crown is a unique method for prolonging its lifetime from an economic point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, often at a job site on a ship, a piston crown is actually welded with mild filler metals. Therefore, in this study, mild filler metals such as CSF350H, E8000B2, and 435 were welded to SS401 steel as the base metal, and the corrosion properties of the weld metals with and without post weld heat treatment were investigated using some electrochemical methods in a 0.1% $H_2SO_4$ solution. The weld metal welded with CSF350H filler metal exhibited the best corrosion resistance among these filler metals, irrespective of the heat treatment. However, the weld metal zones of the E8000B2 and 435 filler metals exhibited better and worse corrosion resistance with the heat treatment, respectively. As a result, it is suggested that in the case of repair welding with CSF350H and 435 filler metals, no heat treatment is advisable, while heat treatment is desirable if E8000B2filler metal is used with repair welding.

• Safety and Health at Work
• /
• 제14권2호
• /
• pp.215-221
• /
• 2023

Background: There is little information about the airborne hazardous agents released during the heat treatment when manufacturing a welding material. This study aimed to evaluate the airborne hazardous agents generated at welding material manufacturing sites through area sampling. Methods: concentration of airborne particles was measured using a scanning mobility particle sizer and optical particle sizer. Total suspended particles (TSP) and respirable dust samples were collected on polyvinyl chloride filters and weighed to measure the mass concentrations. Volatile organic compounds and heavy metals were analyzed using a gas chromatography mass spectrometer and inductively coupled plasma mass spectrometer, respectively. Results: The average mass concentration of TSP was 683.1±677.4 ㎍/m³, with respirable dust accounting for 38.6% of the TSP. The average concentration of the airborne particles less than 10 ㎛ in diameter was 11.2-22.8×10⁴ particles/cm³, and the average number of the particles with a diameter of 10-100 nm was approximately 78-86% of the total measured particles (<10 ㎛). In the case of volatile organic compounds, the heat treatment process concentration was significantly higher (p < 0.05) during combustion than during cooling. The airborne heavy metal concentrations differed depending on the materials used for heat treatment. The content of heavy metals in the airborne particles was approximately 32.6%. Conclusions: Nanoparticle exposure increased as the number of particles in the air around the heat treatment process increases, and the ratio of heavy metals in dust generated after the heat treatment process is high, which may adversely affect workers' health.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집A
• /
• pp.73-78
• /
• 2000

On this study, the fatigue crack propagation of super duplex stainless steel is investigated in conditions of various volume fraction of austenite phase by changing heat treatment temperature. And we analysed acoustic emission signals during the fatigue test by time-frequency analysis methods. As the temperature of heat treatment increased, volume fraction of austenite decreased and coarse grain was obtained. The specimen heat treated at $1200^{\circ}C$ had longer fatigue life and slower rate of crack growth. As a result of time-frequency analyze of acoustic emission signals during fatigue test, main frequency was $200{\sim}300kHz$ having no correlation with heat treatment and crack length, and 500kHz was obtained by dimple and separate of inclusion

• 열처리공학회지
• /
• 제25권5호
• /
• pp.227-232
• /
• 2012

Magnesium alloy have good physical properties such as good castability, good vibration absorption, high strength/weight ratios. Despite the desirable properties, the poor resistance of Mg alloy impedes their use in many various applications. Therefore, magnesium alloy require surface treatment to improve hardness, corrosion and wear resistance. Plasma Electrolytic Oxidation (PEO) is one the surface treatment methods to form oxide layer on Mg alloy in alkali electrolyte. In comparison with Anodizing, there is environmental process having higher hardness and faster deposition rate. In this study, the characteristics of oxide film were examined after coating the AZ31 Mg alloy through the PEO process. We changed concentration of sodium aluminate into $K_2ZrF_6$, KF base electrolyte. The morphologies of the coating layer were characterized by using scanning electron microscopy (SEM). Corrosion resistance also investigated by potentiodynamic polarization analysis. As a result, propertiy of oxide layer were changed by concentration of sodium aluminate. Increasing with concentration of sodium aluminate in electrolyte, the oxidation layer was denser and the pore size was smaller on the surface.

• 사상체질의학회지
• /
• 제29권4호
• /
• pp.376-386
• /
• 2017

Objectives This case study is about a Taeeumin patient with Parkinson's disease identified as Dry-heat (Joyeol) pattern. In this study, we report significant improvement of motor and non-motor symptoms of this patient after Sasang constitutional medicine treatment. Methods The patient was identified as Taeeumin Dry-heat pattern and treated with Cheongsimyeonja-tang and acupuncture. The Unified Parkinson Disease Rating Scale(UPDRS) was used to assess the overall function of the patient. And the Global Assessment Scale (GAS) was used to assess the change of bradykinesia, tremor and dry mouth after the treatment. Results The UPDRS total score decreased from 145 points to 77 points after 5 weeks treatment. And symptoms of bradykinesia, tremor and dry mouth showed significant improvement in GAS after the treatment. Furthermore, constipation, sleep disturbance, dysuresia and anorexia were reported to be improved after treatment. Conclusions This study shows that Sasang constitutional medicine can be effective treatment for motor and non-motor symptoms caused by Parkinson's disease.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.821-825
• /
• 2002

ZnO thick films by Sol-Gel processing were investigated electrics, optics and the sensing characteristics of CO gas. Using the znic acetate dihydrate and acetylaceton (AcAc) as a chelating agent, stable ZnO sol was synthesized. ZnO phase was crystallized through the heat-treatment at $70^{\circ}C$ for 4hrs and influenced the sensing characteristics of the electrics and CO gas by uniform particle distributions not related particle size. The samples on the alumina substrate by thick films were investigated the properties of electrics and the effect of sensing. The sensitivity was so excellent in the sample of the heat-treatment at $600^{\circ}C$ for 12hrs and good in the heat-treatment for 1hrs generally. Crystallization and volatilization of organic materials according to the change of heating treatment temperature of thick films were analyzed by TG-DTA, XRD and mirostructure of thick films were observed by SEM.

• 대한약침학회지
• /
• 제9권2호
• /
• pp.135-140
• /
• 2006

Object : This study is designed in order to evaluate oriental medical treatment of ankylosing spondylitis. Methods : The authors observed patient by ROM & VAS for operated acupuncture treatment, herbal medicine treatment and physiotherapy Conclusion : 1. Ankylosing spondylitis patient of this case is caused by taiyang channel warm-heat evi. 2. Ankylosing spondylitis patient by taiyang channel warm-heat evi is evaluated by acupuncture treatment. ; SP3, S36, LIll, LI4, S40. 3. Ankylosing spondylitis patient by taiyang channel warm-heat evi is evaluated by Hervbal medication. ; Gamikangwhalsungsub-Tang.

• Applied Biological Chemistry
• /
• 제35권6호
• /
• pp.490-494
• /
• 1992

두부의 저장성 향상을 위해 포장한 후 가열처리하여 저장 중 두부의 미생물상과 이화학적인 변화를 검토하였다. 두부는 $CaCl_2$보다 초산으로 응고시키는 것이 저장성 향상에 효과적이었으며, 두부의 저장기간이 경과함에 따라 적정산도, amino태 질소 및 ammonia태질소와 두부현탁액의 탁도는 증가하였다. 두부를 포장하여 가열처리하면 저장초기의 세균수를 효과적으로 줄일 수 있어 저장성을 연장할 수 있었으나 직접가열과 마이크로파 가열간의 차이는 적었다. 초산으로 응고시킨 비가열처리 두부는 $30^{\circ}C$에서 1일만에 세균수가 $6.6{\times}10^6\;CFU/g$에 도달하여 저장성이 감소하며 3분간 가열처리하면 4일간 저장이 가능하였다.