Seung-Hun Kim

Correlation between a Cutometer® and quantitative evaluation using Moire topography in age‐related skin elasticity

Background/purpose: As aging occurs, our skin gets more wrinkles, becomes drier and loses its elasticity. Validating the evaluation of skin elasticity is especially important, because it is not as visible as other signs of aging such as wrinkles. So it is needed that the method for measuring skin elasticity is able to reflect perception about the change of the skin state.

Comparison and correlation between stinging responses to lactic acid and bioengineering parameters

In evaluating the safety of a novel cosmetic product or a new chemical, it is important to assess susceptible population. One group of subjects is known to stingers who are more likely to experience sensory effects such as stinging and burning after contacting with cosmetics. The purpose of the study is to measure skin biophysical parameters noninvasively in stingers and non‐stingers and to see their correlations with stinging responses. 298 women were evaluated by modified lactic acid stinging test with 5% lactic acid solution rather than classic 10% solution because of strong reaction in Asian populations. Transepidermal water loss (TEWL), skin hydration, sebum content, and pH were measured using the bioengineering instruments in an environment‐controlled room. Correlations between stinging responses and skin biophysical parameters were statistically analysed. There was a positive correlation between stinging responses and TEWL evaluation. However, no correlations was observed between stinging responses and other parameters such as skin hydration, sebum content, and pH. Our data indicate that there is a relationship between the degree of stinging and the skin barrier function. However, we believe that various additional studies are necessary to characterize skin of stingers and the pathogenesis.

Influence of polyol and oil concentration in cosmetic products on skin moisturization and skin surface roughness

Background/purpose: The purpose of this study is to investigate the optimum combination of polyols and oils in moisturizing cosmetic products to improve the human skin moisturization and skin surface roughness. Polyols and oils are essential ingredients in skin care products, but it is still not understood how their concentrations affect their efficacy and sensory properties on human skin. We investigated the effect of polyol and oil concentration on skin properties by noninvasive methods.

COMPARISON AND CORRELATION BETWEEN STINGING RESPONSES WITH LACTIC ACID STINGING TEST AND BIOENGINEERING PARAMETERS

from 9 48h to 9 5 min per application decreased the sensitization rate to 1% p-phenylene-diamine (PPD) from 54% to 3%. However, in a clinical study, infrequent longer duration and higher concentration exposure to PPD was significantly less likely to induce sensitization compared to more frequent, short duration, lower concentration exposure. Detailed statistical analysis of the results indicated that the most important factor driving the induction of skin sensitization was the number of exposures. An appreciation of such factors is vital for risk assessments where exposure is likely to be above the skin sensitization induction threshold.