Test loss, Test accuracy 측정시
test_loss, test_acc = model.evaluate(test_images, test_labels, verbose=2)
from sklearn.metrics import accuracy_score
import numpy as np
y_pred = model.predict(test_images)
y_pred = np.argmax(y_pred, axis=1)
print(f"test accuracy: {accuracy_score(test_labels, y_pred) : .4f}")