• 한국표면공학회지
• /
• 제31권6호
• /
• pp.359-370
• /
• 1998

TiAl-based intermetallic compounds were electro-bornizel in the mixture of $Na_2B_4O_7$, KCL and LiCl in the termetature rage between 850 and $1000^{\circ}C$for various times (1-5 hours)under the fixed current density of 0.5 A/$cm^2$. The optimized composition of electrolyte in this work was decided to be 76.9 wt% $Na_2B_4O_7$-19.2 wt.%(0.7KCl-0.3LiCl) -3.9 wt.% al. The samples with boronized layer were investigated by SEM, XRD and EDS. The surface micro-hardness of boronized TiAl was also evaluated using Micro Vickers Hardness Tester. The sample, boronized at $900^{\circ}C$ for 4 hours in the above composition of electrolyte under the current density of 0.5 A/$\textrm{cm}^2$, has about 36$\mu\textrm{m}$ think layer on the surface, and its surface micro-hardness was measured to be 1263 Hv. From the results of SEM, XRD and EDS, the layer consisted of $TiB_2$ sublayer and Al-oxide sub layer. Al-depleted layer below the Al-oxide sudlayer was also detected. The activation energy for formation of boronized layer in this study was calculated as 178 Kcal/moleK.

• Journal of Welding and Joining
• /
• 제14권2호
• /
• pp.36-45
• /
• 1996

Fatigue strength of the spot welded lap joint is considerably influenced by corrosive environments. Particularly, the chloride and the sulfide are most injurious to strength of the spot welded lap joint. Therefore, there is a need to evaluate its effect to corrosion fatigue strength for safe life design of spot welded structures. In order to evaluate their corrosion fatigue strength, corrosion fatigue tests on the spot welded lap joints of the uncoated and the coated high strength steel sheets were conducted in air and in 10% NaCl solution. Corrosion fatigue strength of the uncoated specimens were entirely lower than the coated one in NaCl solution, but those of the coated specimens in NaCl solution were lower than in air. And stress distribution in single spon welded lap joint subjected to tension-shear load was investigated by the finite element method. Using these results, we tried to evaluate corrosion fatgue strength of the various spot welded lap joints with maximum stress $\sigma_{max}$ at edge on loading side of the spot welded lap joint. We could find that corrosion fatigue strength could be quantitatively and systematically rearranged by $\sigma_{max}$.

• The Korean Journal of Ceramics
• /
• 제6권1호
• /
• pp.32-36
• /
• 2000

Pyrolytic preparations of Ti-Al-N ceramics from three blended precursors were investigated. The precursors were prepared stirring ($HA1N^{i}Pr_m$ and an aminolysis product of $Ti(NMe_2)_4$ with $MeHNCH_2CH_2$NHMe in $C_6/H_6$ . IR and $^1H\;NMR $analyses suggested that essentially no Ti-N-Al bonds were present in the precursors. Pyrolysis of the precursors under $NH_3-N_2$led to the formation of brown solids with ceramic yields of about 30%, and the Ti-Al ratios in the pyrolyzed products were close to those of the precursors. XRD analysis of the pyrolyzed product from the precursor with Ti:Al=5:1 indicated the formation of a NaCl-type compound as the only crystalline phase. Pyrolysis of the precursor with Ti:Al=2:1 led to the formation of AlN besides the major NaCl-type compound. A ceramic composite containing AlN and the NaCl-type compound was formed by pyrolysis of the precursor with Ti:Al=1:2.

• Transactions on Electrical and Electronic Materials
• /
• 제15권3호
• /
• pp.164-169
• /
• 2014

We investigated the etching characteristics of $HfAlO_3$ thin films in $O_2/Cl_2/Ar$ and $O_2/BCl_3/Ar$ gas, using a high-density plasma (HDP) system. The etch rates of the $HfAlO_3$ thin film obtained were 30.1 nm/min and 36 nm/min in the $O_2/Cl_2/Ar$ (3:4:16 sccm) and $O_2/BCl_3/Ar$ (3:4:16 sccm) gas mixtures, respectively. At the same time, the etch rate was measured as a function of the etching parameter, namely as the process pressure. The chemical states on the surface of the etched $HfAlO_3$ thin films were investigated by X-ray photoelectron spectroscopy. Auger electron spectroscopy was used for elemental analysis on the surface of the etched $HfAlO_3$ thin films. These surface analyses confirm that the surface of the etched $HfAlO_3$ thin film is formed with nonvolatile by-product. Also, Cl-O can protect the sidewall due to additional $O_2$.

• Corrosion Science and Technology
• /
• 제3권6호
• /
• pp.245-250
• /
• 2004

A series of classical G109 type concrete specimens was exposed to cyclic wet and dry ponding with 15 w/o NaCl solution for approximately five years. Mix design variables included 1) three cement alkalinities (EqA of 0.97, 0.52, and 0.36) and 2) three water-cement ratios (0.50, 0.41, and 0.37). To determine the corrosion initiation time, corrosion potential and macro-cell current between top and bottom bars were monitored. Subsequent to corrosion initiation, specimens were autopsied and visually inspected. Concrete powder samples were collected from top rebar trace and chloride concentration was measured. Also, time-to-corrosion, $T_i$, for specimens of the individual mix designs was represented using Weibull analysis. Time-to-corrosion was a distributed parameter; and because of this, corrosion initiation of four identical specimens for each mix varied, often over a relatively wide range. Specimens fabricated using the lowest water cement ratio and the highest alkalinity cement exhibited the longest time-to-corrosion initiation and the highest chloride threshold levels. Time-to-corrosion did not increase monotonically with cement alkalinity, however, presumably as a consequence of relatively high $Cl^-$ binding in the lower pore water pH range. The chloride threshold level, $Cl_{th}$, increased with increasing $T_i$ and, consequently, was greatest for the highest cement alkalinity specimens.

• KSBB Journal
• /
• 제8권3호
• /
• pp.282-286
• /
• 1993

회분식 포말분리관에 효모용액을 충전하여 효모분리실험을 수행하며 효모 액면 높이, 질소 공급량, 효모농도, pH와 온도 및 $CaCl_2$ 첨가 등의 변화에 따른 포말 분리관의 분리 및 특성 등을 연구하였다. 액면 높이가 20cm인 경우 최대 효모분리비 70.6을 얻을 수 있었고 포말 생성시간도 6분으로 가장 길었다. 질소 공급량이 120ml/min인 경우 3분 분리운전후 액본체 효모의 90~94%가 제거되어 매우 신속하고 효과적인 분리법이었다. 효모농도가 3.92~8.4g/l 범위가 pH가 5~7 범위에서 분리시간에 따른 효모 제거율은 비슷하였다. 효모용액의 온도가 26~$36^{\circ}C$ 범위에서 온도가 상승할수록 분리시간에 따른 효모 분리비가 증대하였다. 효모의 응집성을 증대하는 $CaCl_2$ 농도는 0.2g/l일 때 효모 분리비가 가장 높았다.

• 약학회지
• /
• 제36권4호
• /
• pp.390-396
• /
• 1992

Streptomyces minoensis DMCJ-144 isolated from soil produces the ${\alpha}-amylase$ inhibitor. Optimum culture conditions for ${\alpha}-amylase$ inhibitor production of the strain were determined in this experiment. The optimum composition of the culture medium was studied by supplementing various carbon sources, nitrogen sources, vitamins, and metal salts to the basal medium containing 1% glucose, 0.1% asparagine, 0.005% $MgSO_4{\cdot}7H_2O$, 0.005% $K_2HPO_4$, 0.005% NaCl. Other culture conditions such as the culture temperature, initial pH of the medium, aeration, and culture time were also investigated. When the strain was cultured in a 100 ml flask containing 20 ml of 2% glucose, 0.5% beef extract, 0.0002% riboflavin, 0.0002% thiamine HCI, 0.01% $ZnCl_2$, 0.005% $MgSO_4{\cdot}7H_2O$, 0.005% $CuSO_4{\cdot}5H_2O$, 0.005% NaCl, pH 7.2, 180 rpm at $30^{\circ}C$, the maximum production of the ${\alpha}-amylase$ inhibitor was observed after 5 days of the cultivation.

• The Korean Journal of Pain
• /
• 제28권1호
• /
• pp.39-44
• /
• 2015

Background: Postoperative nausea and vomiting (PONV), postanesthetic shivering and pain are common postoperative patient complaints that can result in adverse physical and psychological outcomes. Some antiemetics are reported to be effective in the management of postoperative pain and shivering, as well as PONV. We evaluated the efficacy of dexamethasone added to ramosetron on PONV, shivering and pain after thyroid surgery. Methods: One hundred and eight patients scheduled for thyroid surgery were randomly allocated to three different groups: the control group (group C, n = 36), the ramosetron group (group R, n = 36), or the ramosetron plus dexamethasone group (group RD, n = 36). The patients were treated intravenously with 1 and 2 ml of 0.9% NaCl (group C); or 2 ml of 0.15 mg/ml ramosetron plus 1 ml of 0.9% NaCl (group R); or 2 ml of 0.15 mg/ml ramosetron plus 1 ml of 5 mg/ml dexamethasone (group RD) immediately after anesthesia. Results: Incidence of nausea and the need for rescue antiemetics, verbal rating scale (VRS) 1 hour pain value, ketorolac consumption, and incidence of shivering were significantly lower in group R and group RD, than in group C (P < 0.05). Moreover, these parameters were significantly lower in group RD than in group R (P < 0.05). Conclusions: Combination of ramosetron and dexamethasone significantly reduced not only the incidence of nausea and need for rescue antiemetics, but also the VRS 1 hour pain value, ketorolac consumption, and the incidence of shivering compared to ramosetron alone in patients undergoing thyroid surgery.

• 한국미생물·생명공학회지
• /
• 제46권4호
• /
• pp.313-319
• /
• 2018

Halophilic lactic acid bacteria (LAB) were isolated from myeolchi-jeotgal (23% NaCl, w/v) fermented in jangdok (Korean earthenware) located outside a house. They were identified as Tetragenococcus halophilus by 16S rRNA and recA gene sequencing. Four T. halophilus isolates showing high protease activities were selected for further studies. Four strains grew well, reaching $OD_{600}$ values of 0.75-0.92 at 18% NaCl content (w/v) and 0.28-0.44 at 23% salt. They showed rapid growth, attaining $OD_{600}$ values of 1.1-1.2 at $20-30^{\circ}C$, but did not grow at $4^{\circ}C$. At $15^{\circ}C$, the highest $OD_{600}$ values, which exceeded 0.6, were observed at 20 days, and were higher than those of cultures at $37^{\circ}C$ and $42^{\circ}C$ (approximately 0.5). Four isolates grew best in broth where the initial pH was adjusted to 8 and did not grow at $pH{\leq}4$. T. halophilus BS2-36 showed the highest survival ratio of 18.7% after 2 hours of exposure at pH 3. BS2-36 showed the highest survival ratio (1.29%) in presence of 0.3% bile salts. T. halophilus BS2-36 seems a promising candidate as a starter for jeotgal and other fermented foods with high salinities.

• 한국가금학회지
• /
• 제27권1호
• /
• pp.1-6
• /
• 2000

An experiment was conducted to determine the nutritional values and variations of food wastes according to seasons and sources. Food wastes were sampled monthly from Feb. to Aug. at gathering sites from home kitchens, school restaurants and Korean food restaurants. chemical analyses revealed that crude fiber and NaCl contents were in the range of 5.41∼10.36 and 3.67∼5.40%, respectively, and the variations were especially high in summer. Ash content was highest in spring. With regard to the sources, the wastes from Korean food restaurants was highest in ash, calcium and phosphorus. On the other hand, crude fiber and fat were highest in the waste from house kitchens and NaCl in those from school restaurants.